1532 lines
51 KiB
Python
1532 lines
51 KiB
Python
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# engine/result.py
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# Copyright (C) 2005-2019 the SQLAlchemy authors and contributors
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# <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: http://www.opensource.org/licenses/mit-license.php
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"""Define result set constructs including :class:`.ResultProxy`
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and :class:`.RowProxy."""
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import collections
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import operator
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from .. import exc
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from .. import util
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from ..sql import expression
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from ..sql import sqltypes
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from ..sql import util as sql_util
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# This reconstructor is necessary so that pickles with the C extension or
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# without use the same Binary format.
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try:
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# We need a different reconstructor on the C extension so that we can
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# add extra checks that fields have correctly been initialized by
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# __setstate__.
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from sqlalchemy.cresultproxy import safe_rowproxy_reconstructor
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# The extra function embedding is needed so that the
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# reconstructor function has the same signature whether or not
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# the extension is present.
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def rowproxy_reconstructor(cls, state):
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return safe_rowproxy_reconstructor(cls, state)
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except ImportError:
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def rowproxy_reconstructor(cls, state):
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obj = cls.__new__(cls)
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obj.__setstate__(state)
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return obj
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try:
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from sqlalchemy.cresultproxy import BaseRowProxy
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_baserowproxy_usecext = True
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except ImportError:
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_baserowproxy_usecext = False
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class BaseRowProxy(object):
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__slots__ = ("_parent", "_row", "_processors", "_keymap")
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def __init__(self, parent, row, processors, keymap):
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"""RowProxy objects are constructed by ResultProxy objects."""
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self._parent = parent
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self._row = row
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self._processors = processors
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self._keymap = keymap
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def __reduce__(self):
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return (
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rowproxy_reconstructor,
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(self.__class__, self.__getstate__()),
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)
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def values(self):
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"""Return the values represented by this RowProxy as a list."""
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return list(self)
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def __iter__(self):
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for processor, value in zip(self._processors, self._row):
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if processor is None:
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yield value
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else:
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yield processor(value)
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def __len__(self):
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return len(self._row)
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def __getitem__(self, key):
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try:
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processor, obj, index = self._keymap[key]
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except KeyError:
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processor, obj, index = self._parent._key_fallback(key)
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except TypeError:
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if isinstance(key, slice):
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l = []
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for processor, value in zip(
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self._processors[key], self._row[key]
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):
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if processor is None:
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l.append(value)
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else:
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l.append(processor(value))
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return tuple(l)
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else:
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raise
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if index is None:
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raise exc.InvalidRequestError(
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"Ambiguous column name '%s' in "
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"result set column descriptions" % obj
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)
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if processor is not None:
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return processor(self._row[index])
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else:
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return self._row[index]
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def __getattr__(self, name):
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try:
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return self[name]
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except KeyError as e:
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raise AttributeError(e.args[0])
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class RowProxy(BaseRowProxy):
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"""Proxy values from a single cursor row.
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Mostly follows "ordered dictionary" behavior, mapping result
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values to the string-based column name, the integer position of
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the result in the row, as well as Column instances which can be
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mapped to the original Columns that produced this result set (for
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results that correspond to constructed SQL expressions).
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"""
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__slots__ = ()
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def __contains__(self, key):
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return self._parent._has_key(key)
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def __getstate__(self):
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return {"_parent": self._parent, "_row": tuple(self)}
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def __setstate__(self, state):
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self._parent = parent = state["_parent"]
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self._row = state["_row"]
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self._processors = parent._processors
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self._keymap = parent._keymap
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__hash__ = None
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def _op(self, other, op):
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return (
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op(tuple(self), tuple(other))
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if isinstance(other, RowProxy)
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else op(tuple(self), other)
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)
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def __lt__(self, other):
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return self._op(other, operator.lt)
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def __le__(self, other):
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return self._op(other, operator.le)
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def __ge__(self, other):
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return self._op(other, operator.ge)
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def __gt__(self, other):
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return self._op(other, operator.gt)
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def __eq__(self, other):
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return self._op(other, operator.eq)
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def __ne__(self, other):
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return self._op(other, operator.ne)
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def __repr__(self):
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return repr(sql_util._repr_row(self))
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def has_key(self, key):
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"""Return True if this RowProxy contains the given key."""
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return self._parent._has_key(key)
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def items(self):
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"""Return a list of tuples, each tuple containing a key/value pair."""
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# TODO: no coverage here
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return [(key, self[key]) for key in self.keys()]
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def keys(self):
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"""Return the list of keys as strings represented by this RowProxy."""
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return self._parent.keys
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def iterkeys(self):
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return iter(self._parent.keys)
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def itervalues(self):
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return iter(self)
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try:
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# Register RowProxy with Sequence,
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# so sequence protocol is implemented
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util.collections_abc.Sequence.register(RowProxy)
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except ImportError:
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pass
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class ResultMetaData(object):
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"""Handle cursor.description, applying additional info from an execution
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context."""
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__slots__ = (
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"_keymap",
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"case_sensitive",
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"matched_on_name",
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"_processors",
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"keys",
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"_orig_processors",
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)
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def __init__(self, parent, cursor_description):
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context = parent.context
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dialect = context.dialect
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self.case_sensitive = dialect.case_sensitive
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self.matched_on_name = False
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self._orig_processors = None
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if context.result_column_struct:
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result_columns, cols_are_ordered, textual_ordered = (
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context.result_column_struct
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)
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num_ctx_cols = len(result_columns)
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else:
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result_columns = (
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cols_are_ordered
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) = num_ctx_cols = textual_ordered = False
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# merge cursor.description with the column info
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# present in the compiled structure, if any
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raw = self._merge_cursor_description(
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context,
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cursor_description,
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result_columns,
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num_ctx_cols,
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cols_are_ordered,
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textual_ordered,
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)
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self._keymap = {}
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if not _baserowproxy_usecext:
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# keymap indexes by integer index: this is only used
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# in the pure Python BaseRowProxy.__getitem__
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# implementation to avoid an expensive
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# isinstance(key, util.int_types) in the most common
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# case path
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len_raw = len(raw)
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self._keymap.update(
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[(elem[0], (elem[3], elem[4], elem[0])) for elem in raw]
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+ [
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(elem[0] - len_raw, (elem[3], elem[4], elem[0]))
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for elem in raw
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]
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)
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# processors in key order for certain per-row
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# views like __iter__ and slices
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self._processors = [elem[3] for elem in raw]
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# keymap by primary string...
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by_key = dict([(elem[2], (elem[3], elem[4], elem[0])) for elem in raw])
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# for compiled SQL constructs, copy additional lookup keys into
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# the key lookup map, such as Column objects, labels,
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# column keys and other names
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if num_ctx_cols:
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# if by-primary-string dictionary smaller (or bigger?!) than
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# number of columns, assume we have dupes, rewrite
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# dupe records with "None" for index which results in
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# ambiguous column exception when accessed.
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if len(by_key) != num_ctx_cols:
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seen = set()
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for rec in raw:
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key = rec[1]
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if key in seen:
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# this is an "ambiguous" element, replacing
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# the full record in the map
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key = key.lower() if not self.case_sensitive else key
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by_key[key] = (None, key, None)
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seen.add(key)
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# copy secondary elements from compiled columns
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# into self._keymap, write in the potentially "ambiguous"
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# element
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self._keymap.update(
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[
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(obj_elem, by_key[elem[2]])
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for elem in raw
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if elem[4]
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for obj_elem in elem[4]
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]
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)
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# if we did a pure positional match, then reset the
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# original "expression element" back to the "unambiguous"
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# entry. This is a new behavior in 1.1 which impacts
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# TextAsFrom but also straight compiled SQL constructs.
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if not self.matched_on_name:
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self._keymap.update(
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[
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(elem[4][0], (elem[3], elem[4], elem[0]))
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for elem in raw
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if elem[4]
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]
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)
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else:
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# no dupes - copy secondary elements from compiled
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# columns into self._keymap
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self._keymap.update(
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[
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(obj_elem, (elem[3], elem[4], elem[0]))
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for elem in raw
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if elem[4]
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for obj_elem in elem[4]
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]
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)
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# update keymap with primary string names taking
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# precedence
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self._keymap.update(by_key)
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# update keymap with "translated" names (sqlite-only thing)
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if not num_ctx_cols and context._translate_colname:
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self._keymap.update(
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[(elem[5], self._keymap[elem[2]]) for elem in raw if elem[5]]
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)
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def _merge_cursor_description(
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self,
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context,
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cursor_description,
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result_columns,
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num_ctx_cols,
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cols_are_ordered,
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textual_ordered,
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):
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"""Merge a cursor.description with compiled result column information.
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There are at least four separate strategies used here, selected
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depending on the type of SQL construct used to start with.
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The most common case is that of the compiled SQL expression construct,
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which generated the column names present in the raw SQL string and
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which has the identical number of columns as were reported by
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cursor.description. In this case, we assume a 1-1 positional mapping
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between the entries in cursor.description and the compiled object.
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This is also the most performant case as we disregard extracting /
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decoding the column names present in cursor.description since we
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already have the desired name we generated in the compiled SQL
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construct.
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The next common case is that of the completely raw string SQL,
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such as passed to connection.execute(). In this case we have no
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compiled construct to work with, so we extract and decode the
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names from cursor.description and index those as the primary
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result row target keys.
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The remaining fairly common case is that of the textual SQL
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that includes at least partial column information; this is when
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we use a :class:`.TextAsFrom` construct. This construct may have
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unordered or ordered column information. In the ordered case, we
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merge the cursor.description and the compiled construct's information
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positionally, and warn if there are additional description names
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present, however we still decode the names in cursor.description
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as we don't have a guarantee that the names in the columns match
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on these. In the unordered case, we match names in cursor.description
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to that of the compiled construct based on name matching.
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In both of these cases, the cursor.description names and the column
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expression objects and names are indexed as result row target keys.
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The final case is much less common, where we have a compiled
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non-textual SQL expression construct, but the number of columns
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in cursor.description doesn't match what's in the compiled
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construct. We make the guess here that there might be textual
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column expressions in the compiled construct that themselves include
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a comma in them causing them to split. We do the same name-matching
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as with textual non-ordered columns.
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The name-matched system of merging is the same as that used by
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|
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SQLAlchemy for all cases up through te 0.9 series. Positional
|
||
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matching for compiled SQL expressions was introduced in 1.0 as a
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major performance feature, and positional matching for textual
|
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:class:`.TextAsFrom` objects in 1.1. As name matching is no longer
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a common case, it was acceptable to factor it into smaller generator-
|
||
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oriented methods that are easier to understand, but incur slightly
|
||
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more performance overhead.
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||
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"""
|
||
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case_sensitive = context.dialect.case_sensitive
|
||
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if (
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|
num_ctx_cols
|
||
|
|
and cols_are_ordered
|
||
|
|
and not textual_ordered
|
||
|
|
and num_ctx_cols == len(cursor_description)
|
||
|
|
):
|
||
|
|
self.keys = [elem[0] for elem in result_columns]
|
||
|
|
# pure positional 1-1 case; doesn't need to read
|
||
|
|
# the names from cursor.description
|
||
|
|
return [
|
||
|
|
(
|
||
|
|
idx,
|
||
|
|
key,
|
||
|
|
name.lower() if not case_sensitive else name,
|
||
|
|
context.get_result_processor(
|
||
|
|
type_, key, cursor_description[idx][1]
|
||
|
|
),
|
||
|
|
obj,
|
||
|
|
None,
|
||
|
|
)
|
||
|
|
for idx, (key, name, obj, type_) in enumerate(result_columns)
|
||
|
|
]
|
||
|
|
else:
|
||
|
|
# name-based or text-positional cases, where we need
|
||
|
|
# to read cursor.description names
|
||
|
|
if textual_ordered:
|
||
|
|
# textual positional case
|
||
|
|
raw_iterator = self._merge_textual_cols_by_position(
|
||
|
|
context, cursor_description, result_columns
|
||
|
|
)
|
||
|
|
elif num_ctx_cols:
|
||
|
|
# compiled SQL with a mismatch of description cols
|
||
|
|
# vs. compiled cols, or textual w/ unordered columns
|
||
|
|
raw_iterator = self._merge_cols_by_name(
|
||
|
|
context, cursor_description, result_columns
|
||
|
|
)
|
||
|
|
else:
|
||
|
|
# no compiled SQL, just a raw string
|
||
|
|
raw_iterator = self._merge_cols_by_none(
|
||
|
|
context, cursor_description
|
||
|
|
)
|
||
|
|
|
||
|
|
return [
|
||
|
|
(
|
||
|
|
idx,
|
||
|
|
colname,
|
||
|
|
colname,
|
||
|
|
context.get_result_processor(
|
||
|
|
mapped_type, colname, coltype
|
||
|
|
),
|
||
|
|
obj,
|
||
|
|
untranslated,
|
||
|
|
)
|
||
|
|
for (
|
||
|
|
idx,
|
||
|
|
colname,
|
||
|
|
mapped_type,
|
||
|
|
coltype,
|
||
|
|
obj,
|
||
|
|
untranslated,
|
||
|
|
) in raw_iterator
|
||
|
|
]
|
||
|
|
|
||
|
|
def _colnames_from_description(self, context, cursor_description):
|
||
|
|
"""Extract column names and data types from a cursor.description.
|
||
|
|
|
||
|
|
Applies unicode decoding, column translation, "normalization",
|
||
|
|
and case sensitivity rules to the names based on the dialect.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
dialect = context.dialect
|
||
|
|
case_sensitive = dialect.case_sensitive
|
||
|
|
translate_colname = context._translate_colname
|
||
|
|
description_decoder = (
|
||
|
|
dialect._description_decoder
|
||
|
|
if dialect.description_encoding
|
||
|
|
else None
|
||
|
|
)
|
||
|
|
normalize_name = (
|
||
|
|
dialect.normalize_name if dialect.requires_name_normalize else None
|
||
|
|
)
|
||
|
|
untranslated = None
|
||
|
|
|
||
|
|
self.keys = []
|
||
|
|
|
||
|
|
for idx, rec in enumerate(cursor_description):
|
||
|
|
colname = rec[0]
|
||
|
|
coltype = rec[1]
|
||
|
|
|
||
|
|
if description_decoder:
|
||
|
|
colname = description_decoder(colname)
|
||
|
|
|
||
|
|
if translate_colname:
|
||
|
|
colname, untranslated = translate_colname(colname)
|
||
|
|
|
||
|
|
if normalize_name:
|
||
|
|
colname = normalize_name(colname)
|
||
|
|
|
||
|
|
self.keys.append(colname)
|
||
|
|
if not case_sensitive:
|
||
|
|
colname = colname.lower()
|
||
|
|
|
||
|
|
yield idx, colname, untranslated, coltype
|
||
|
|
|
||
|
|
def _merge_textual_cols_by_position(
|
||
|
|
self, context, cursor_description, result_columns
|
||
|
|
):
|
||
|
|
num_ctx_cols = len(result_columns) if result_columns else None
|
||
|
|
|
||
|
|
if num_ctx_cols > len(cursor_description):
|
||
|
|
util.warn(
|
||
|
|
"Number of columns in textual SQL (%d) is "
|
||
|
|
"smaller than number of columns requested (%d)"
|
||
|
|
% (num_ctx_cols, len(cursor_description))
|
||
|
|
)
|
||
|
|
seen = set()
|
||
|
|
for (
|
||
|
|
idx,
|
||
|
|
colname,
|
||
|
|
untranslated,
|
||
|
|
coltype,
|
||
|
|
) in self._colnames_from_description(context, cursor_description):
|
||
|
|
if idx < num_ctx_cols:
|
||
|
|
ctx_rec = result_columns[idx]
|
||
|
|
obj = ctx_rec[2]
|
||
|
|
mapped_type = ctx_rec[3]
|
||
|
|
if obj[0] in seen:
|
||
|
|
raise exc.InvalidRequestError(
|
||
|
|
"Duplicate column expression requested "
|
||
|
|
"in textual SQL: %r" % obj[0]
|
||
|
|
)
|
||
|
|
seen.add(obj[0])
|
||
|
|
else:
|
||
|
|
mapped_type = sqltypes.NULLTYPE
|
||
|
|
obj = None
|
||
|
|
|
||
|
|
yield idx, colname, mapped_type, coltype, obj, untranslated
|
||
|
|
|
||
|
|
def _merge_cols_by_name(self, context, cursor_description, result_columns):
|
||
|
|
dialect = context.dialect
|
||
|
|
case_sensitive = dialect.case_sensitive
|
||
|
|
result_map = self._create_result_map(result_columns, case_sensitive)
|
||
|
|
|
||
|
|
self.matched_on_name = True
|
||
|
|
for (
|
||
|
|
idx,
|
||
|
|
colname,
|
||
|
|
untranslated,
|
||
|
|
coltype,
|
||
|
|
) in self._colnames_from_description(context, cursor_description):
|
||
|
|
try:
|
||
|
|
ctx_rec = result_map[colname]
|
||
|
|
except KeyError:
|
||
|
|
mapped_type = sqltypes.NULLTYPE
|
||
|
|
obj = None
|
||
|
|
else:
|
||
|
|
obj = ctx_rec[1]
|
||
|
|
mapped_type = ctx_rec[2]
|
||
|
|
yield idx, colname, mapped_type, coltype, obj, untranslated
|
||
|
|
|
||
|
|
def _merge_cols_by_none(self, context, cursor_description):
|
||
|
|
for (
|
||
|
|
idx,
|
||
|
|
colname,
|
||
|
|
untranslated,
|
||
|
|
coltype,
|
||
|
|
) in self._colnames_from_description(context, cursor_description):
|
||
|
|
yield idx, colname, sqltypes.NULLTYPE, coltype, None, untranslated
|
||
|
|
|
||
|
|
@classmethod
|
||
|
|
def _create_result_map(cls, result_columns, case_sensitive=True):
|
||
|
|
d = {}
|
||
|
|
for elem in result_columns:
|
||
|
|
key, rec = elem[0], elem[1:]
|
||
|
|
if not case_sensitive:
|
||
|
|
key = key.lower()
|
||
|
|
if key in d:
|
||
|
|
# conflicting keyname, just double up the list
|
||
|
|
# of objects. this will cause an "ambiguous name"
|
||
|
|
# error if an attempt is made by the result set to
|
||
|
|
# access.
|
||
|
|
e_name, e_obj, e_type = d[key]
|
||
|
|
d[key] = e_name, e_obj + rec[1], e_type
|
||
|
|
else:
|
||
|
|
d[key] = rec
|
||
|
|
return d
|
||
|
|
|
||
|
|
def _key_fallback(self, key, raiseerr=True):
|
||
|
|
map_ = self._keymap
|
||
|
|
result = None
|
||
|
|
if isinstance(key, util.string_types):
|
||
|
|
result = map_.get(key if self.case_sensitive else key.lower())
|
||
|
|
# fallback for targeting a ColumnElement to a textual expression
|
||
|
|
# this is a rare use case which only occurs when matching text()
|
||
|
|
# or colummn('name') constructs to ColumnElements, or after a
|
||
|
|
# pickle/unpickle roundtrip
|
||
|
|
elif isinstance(key, expression.ColumnElement):
|
||
|
|
if (
|
||
|
|
key._label
|
||
|
|
and (key._label if self.case_sensitive else key._label.lower())
|
||
|
|
in map_
|
||
|
|
):
|
||
|
|
result = map_[
|
||
|
|
key._label if self.case_sensitive else key._label.lower()
|
||
|
|
]
|
||
|
|
elif (
|
||
|
|
hasattr(key, "name")
|
||
|
|
and (key.name if self.case_sensitive else key.name.lower())
|
||
|
|
in map_
|
||
|
|
):
|
||
|
|
# match is only on name.
|
||
|
|
result = map_[
|
||
|
|
key.name if self.case_sensitive else key.name.lower()
|
||
|
|
]
|
||
|
|
# search extra hard to make sure this
|
||
|
|
# isn't a column/label name overlap.
|
||
|
|
# this check isn't currently available if the row
|
||
|
|
# was unpickled.
|
||
|
|
if result is not None and result[1] is not None:
|
||
|
|
for obj in result[1]:
|
||
|
|
if key._compare_name_for_result(obj):
|
||
|
|
break
|
||
|
|
else:
|
||
|
|
result = None
|
||
|
|
if result is None:
|
||
|
|
if raiseerr:
|
||
|
|
raise exc.NoSuchColumnError(
|
||
|
|
"Could not locate column in row for column '%s'"
|
||
|
|
% expression._string_or_unprintable(key)
|
||
|
|
)
|
||
|
|
else:
|
||
|
|
return None
|
||
|
|
else:
|
||
|
|
map_[key] = result
|
||
|
|
return result
|
||
|
|
|
||
|
|
def _has_key(self, key):
|
||
|
|
if key in self._keymap:
|
||
|
|
return True
|
||
|
|
else:
|
||
|
|
return self._key_fallback(key, False) is not None
|
||
|
|
|
||
|
|
def _getter(self, key, raiseerr=True):
|
||
|
|
if key in self._keymap:
|
||
|
|
processor, obj, index = self._keymap[key]
|
||
|
|
else:
|
||
|
|
ret = self._key_fallback(key, raiseerr)
|
||
|
|
if ret is None:
|
||
|
|
return None
|
||
|
|
processor, obj, index = ret
|
||
|
|
|
||
|
|
if index is None:
|
||
|
|
raise exc.InvalidRequestError(
|
||
|
|
"Ambiguous column name '%s' in "
|
||
|
|
"result set column descriptions" % obj
|
||
|
|
)
|
||
|
|
|
||
|
|
return operator.itemgetter(index)
|
||
|
|
|
||
|
|
def __getstate__(self):
|
||
|
|
return {
|
||
|
|
"_pickled_keymap": dict(
|
||
|
|
(key, index)
|
||
|
|
for key, (processor, obj, index) in self._keymap.items()
|
||
|
|
if isinstance(key, util.string_types + util.int_types)
|
||
|
|
),
|
||
|
|
"keys": self.keys,
|
||
|
|
"case_sensitive": self.case_sensitive,
|
||
|
|
"matched_on_name": self.matched_on_name,
|
||
|
|
}
|
||
|
|
|
||
|
|
def __setstate__(self, state):
|
||
|
|
# the row has been processed at pickling time so we don't need any
|
||
|
|
# processor anymore
|
||
|
|
self._processors = [None for _ in range(len(state["keys"]))]
|
||
|
|
self._keymap = keymap = {}
|
||
|
|
for key, index in state["_pickled_keymap"].items():
|
||
|
|
# not preserving "obj" here, unfortunately our
|
||
|
|
# proxy comparison fails with the unpickle
|
||
|
|
keymap[key] = (None, None, index)
|
||
|
|
self.keys = state["keys"]
|
||
|
|
self.case_sensitive = state["case_sensitive"]
|
||
|
|
self.matched_on_name = state["matched_on_name"]
|
||
|
|
|
||
|
|
|
||
|
|
class ResultProxy(object):
|
||
|
|
"""Wraps a DB-API cursor object to provide easier access to row columns.
|
||
|
|
|
||
|
|
Individual columns may be accessed by their integer position,
|
||
|
|
case-insensitive column name, or by ``schema.Column``
|
||
|
|
object. e.g.::
|
||
|
|
|
||
|
|
row = fetchone()
|
||
|
|
|
||
|
|
col1 = row[0] # access via integer position
|
||
|
|
|
||
|
|
col2 = row['col2'] # access via name
|
||
|
|
|
||
|
|
col3 = row[mytable.c.mycol] # access via Column object.
|
||
|
|
|
||
|
|
``ResultProxy`` also handles post-processing of result column
|
||
|
|
data using ``TypeEngine`` objects, which are referenced from
|
||
|
|
the originating SQL statement that produced this result set.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
_process_row = RowProxy
|
||
|
|
out_parameters = None
|
||
|
|
_autoclose_connection = False
|
||
|
|
_metadata = None
|
||
|
|
_soft_closed = False
|
||
|
|
closed = False
|
||
|
|
|
||
|
|
def __init__(self, context):
|
||
|
|
self.context = context
|
||
|
|
self.dialect = context.dialect
|
||
|
|
self.cursor = self._saved_cursor = context.cursor
|
||
|
|
self.connection = context.root_connection
|
||
|
|
self._echo = (
|
||
|
|
self.connection._echo and context.engine._should_log_debug()
|
||
|
|
)
|
||
|
|
self._init_metadata()
|
||
|
|
|
||
|
|
def _getter(self, key, raiseerr=True):
|
||
|
|
try:
|
||
|
|
getter = self._metadata._getter
|
||
|
|
except AttributeError:
|
||
|
|
return self._non_result(None)
|
||
|
|
else:
|
||
|
|
return getter(key, raiseerr)
|
||
|
|
|
||
|
|
def _has_key(self, key):
|
||
|
|
try:
|
||
|
|
has_key = self._metadata._has_key
|
||
|
|
except AttributeError:
|
||
|
|
return self._non_result(None)
|
||
|
|
else:
|
||
|
|
return has_key(key)
|
||
|
|
|
||
|
|
def _init_metadata(self):
|
||
|
|
cursor_description = self._cursor_description()
|
||
|
|
if cursor_description is not None:
|
||
|
|
if (
|
||
|
|
self.context.compiled
|
||
|
|
and "compiled_cache" in self.context.execution_options
|
||
|
|
):
|
||
|
|
if self.context.compiled._cached_metadata:
|
||
|
|
self._metadata = self.context.compiled._cached_metadata
|
||
|
|
else:
|
||
|
|
self._metadata = (
|
||
|
|
self.context.compiled._cached_metadata
|
||
|
|
) = ResultMetaData(self, cursor_description)
|
||
|
|
else:
|
||
|
|
self._metadata = ResultMetaData(self, cursor_description)
|
||
|
|
if self._echo:
|
||
|
|
self.context.engine.logger.debug(
|
||
|
|
"Col %r", tuple(x[0] for x in cursor_description)
|
||
|
|
)
|
||
|
|
|
||
|
|
def keys(self):
|
||
|
|
"""Return the current set of string keys for rows."""
|
||
|
|
if self._metadata:
|
||
|
|
return self._metadata.keys
|
||
|
|
else:
|
||
|
|
return []
|
||
|
|
|
||
|
|
@util.memoized_property
|
||
|
|
def rowcount(self):
|
||
|
|
"""Return the 'rowcount' for this result.
|
||
|
|
|
||
|
|
The 'rowcount' reports the number of rows *matched*
|
||
|
|
by the WHERE criterion of an UPDATE or DELETE statement.
|
||
|
|
|
||
|
|
.. note::
|
||
|
|
|
||
|
|
Notes regarding :attr:`.ResultProxy.rowcount`:
|
||
|
|
|
||
|
|
|
||
|
|
* This attribute returns the number of rows *matched*,
|
||
|
|
which is not necessarily the same as the number of rows
|
||
|
|
that were actually *modified* - an UPDATE statement, for example,
|
||
|
|
may have no net change on a given row if the SET values
|
||
|
|
given are the same as those present in the row already.
|
||
|
|
Such a row would be matched but not modified.
|
||
|
|
On backends that feature both styles, such as MySQL,
|
||
|
|
rowcount is configured by default to return the match
|
||
|
|
count in all cases.
|
||
|
|
|
||
|
|
* :attr:`.ResultProxy.rowcount` is *only* useful in conjunction
|
||
|
|
with an UPDATE or DELETE statement. Contrary to what the Python
|
||
|
|
DBAPI says, it does *not* return the
|
||
|
|
number of rows available from the results of a SELECT statement
|
||
|
|
as DBAPIs cannot support this functionality when rows are
|
||
|
|
unbuffered.
|
||
|
|
|
||
|
|
* :attr:`.ResultProxy.rowcount` may not be fully implemented by
|
||
|
|
all dialects. In particular, most DBAPIs do not support an
|
||
|
|
aggregate rowcount result from an executemany call.
|
||
|
|
The :meth:`.ResultProxy.supports_sane_rowcount` and
|
||
|
|
:meth:`.ResultProxy.supports_sane_multi_rowcount` methods
|
||
|
|
will report from the dialect if each usage is known to be
|
||
|
|
supported.
|
||
|
|
|
||
|
|
* Statements that use RETURNING may not return a correct
|
||
|
|
rowcount.
|
||
|
|
|
||
|
|
"""
|
||
|
|
try:
|
||
|
|
return self.context.rowcount
|
||
|
|
except BaseException as e:
|
||
|
|
self.connection._handle_dbapi_exception(
|
||
|
|
e, None, None, self.cursor, self.context
|
||
|
|
)
|
||
|
|
|
||
|
|
@property
|
||
|
|
def lastrowid(self):
|
||
|
|
"""return the 'lastrowid' accessor on the DBAPI cursor.
|
||
|
|
|
||
|
|
This is a DBAPI specific method and is only functional
|
||
|
|
for those backends which support it, for statements
|
||
|
|
where it is appropriate. It's behavior is not
|
||
|
|
consistent across backends.
|
||
|
|
|
||
|
|
Usage of this method is normally unnecessary when
|
||
|
|
using insert() expression constructs; the
|
||
|
|
:attr:`~ResultProxy.inserted_primary_key` attribute provides a
|
||
|
|
tuple of primary key values for a newly inserted row,
|
||
|
|
regardless of database backend.
|
||
|
|
|
||
|
|
"""
|
||
|
|
try:
|
||
|
|
return self._saved_cursor.lastrowid
|
||
|
|
except BaseException as e:
|
||
|
|
self.connection._handle_dbapi_exception(
|
||
|
|
e, None, None, self._saved_cursor, self.context
|
||
|
|
)
|
||
|
|
|
||
|
|
@property
|
||
|
|
def returns_rows(self):
|
||
|
|
"""True if this :class:`.ResultProxy` returns rows.
|
||
|
|
|
||
|
|
I.e. if it is legal to call the methods
|
||
|
|
:meth:`~.ResultProxy.fetchone`,
|
||
|
|
:meth:`~.ResultProxy.fetchmany`
|
||
|
|
:meth:`~.ResultProxy.fetchall`.
|
||
|
|
|
||
|
|
"""
|
||
|
|
return self._metadata is not None
|
||
|
|
|
||
|
|
@property
|
||
|
|
def is_insert(self):
|
||
|
|
"""True if this :class:`.ResultProxy` is the result
|
||
|
|
of a executing an expression language compiled
|
||
|
|
:func:`.expression.insert` construct.
|
||
|
|
|
||
|
|
When True, this implies that the
|
||
|
|
:attr:`inserted_primary_key` attribute is accessible,
|
||
|
|
assuming the statement did not include
|
||
|
|
a user defined "returning" construct.
|
||
|
|
|
||
|
|
"""
|
||
|
|
return self.context.isinsert
|
||
|
|
|
||
|
|
def _cursor_description(self):
|
||
|
|
"""May be overridden by subclasses."""
|
||
|
|
|
||
|
|
return self._saved_cursor.description
|
||
|
|
|
||
|
|
def _soft_close(self):
|
||
|
|
"""Soft close this :class:`.ResultProxy`.
|
||
|
|
|
||
|
|
This releases all DBAPI cursor resources, but leaves the
|
||
|
|
ResultProxy "open" from a semantic perspective, meaning the
|
||
|
|
fetchXXX() methods will continue to return empty results.
|
||
|
|
|
||
|
|
This method is called automatically when:
|
||
|
|
|
||
|
|
* all result rows are exhausted using the fetchXXX() methods.
|
||
|
|
* cursor.description is None.
|
||
|
|
|
||
|
|
This method is **not public**, but is documented in order to clarify
|
||
|
|
the "autoclose" process used.
|
||
|
|
|
||
|
|
.. versionadded:: 1.0.0
|
||
|
|
|
||
|
|
.. seealso::
|
||
|
|
|
||
|
|
:meth:`.ResultProxy.close`
|
||
|
|
|
||
|
|
|
||
|
|
"""
|
||
|
|
if self._soft_closed:
|
||
|
|
return
|
||
|
|
self._soft_closed = True
|
||
|
|
cursor = self.cursor
|
||
|
|
self.connection._safe_close_cursor(cursor)
|
||
|
|
if self._autoclose_connection:
|
||
|
|
self.connection.close()
|
||
|
|
self.cursor = None
|
||
|
|
|
||
|
|
def close(self):
|
||
|
|
"""Close this ResultProxy.
|
||
|
|
|
||
|
|
This closes out the underlying DBAPI cursor corresponding
|
||
|
|
to the statement execution, if one is still present. Note that the
|
||
|
|
DBAPI cursor is automatically released when the :class:`.ResultProxy`
|
||
|
|
exhausts all available rows. :meth:`.ResultProxy.close` is generally
|
||
|
|
an optional method except in the case when discarding a
|
||
|
|
:class:`.ResultProxy` that still has additional rows pending for fetch.
|
||
|
|
|
||
|
|
In the case of a result that is the product of
|
||
|
|
:ref:`connectionless execution <dbengine_implicit>`,
|
||
|
|
the underlying :class:`.Connection` object is also closed, which
|
||
|
|
:term:`releases` DBAPI connection resources.
|
||
|
|
|
||
|
|
After this method is called, it is no longer valid to call upon
|
||
|
|
the fetch methods, which will raise a :class:`.ResourceClosedError`
|
||
|
|
on subsequent use.
|
||
|
|
|
||
|
|
.. versionchanged:: 1.0.0 - the :meth:`.ResultProxy.close` method
|
||
|
|
has been separated out from the process that releases the underlying
|
||
|
|
DBAPI cursor resource. The "auto close" feature of the
|
||
|
|
:class:`.Connection` now performs a so-called "soft close", which
|
||
|
|
releases the underlying DBAPI cursor, but allows the
|
||
|
|
:class:`.ResultProxy` to still behave as an open-but-exhausted
|
||
|
|
result set; the actual :meth:`.ResultProxy.close` method is never
|
||
|
|
called. It is still safe to discard a :class:`.ResultProxy`
|
||
|
|
that has been fully exhausted without calling this method.
|
||
|
|
|
||
|
|
.. seealso::
|
||
|
|
|
||
|
|
:ref:`connections_toplevel`
|
||
|
|
|
||
|
|
:meth:`.ResultProxy._soft_close`
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
if not self.closed:
|
||
|
|
self._soft_close()
|
||
|
|
self.closed = True
|
||
|
|
|
||
|
|
def __iter__(self):
|
||
|
|
"""Implement iteration protocol."""
|
||
|
|
|
||
|
|
while True:
|
||
|
|
row = self.fetchone()
|
||
|
|
if row is None:
|
||
|
|
return
|
||
|
|
else:
|
||
|
|
yield row
|
||
|
|
|
||
|
|
def __next__(self):
|
||
|
|
"""Implement the next() protocol.
|
||
|
|
|
||
|
|
.. versionadded:: 1.2
|
||
|
|
|
||
|
|
"""
|
||
|
|
row = self.fetchone()
|
||
|
|
if row is None:
|
||
|
|
raise StopIteration()
|
||
|
|
else:
|
||
|
|
return row
|
||
|
|
|
||
|
|
next = __next__
|
||
|
|
|
||
|
|
@util.memoized_property
|
||
|
|
def inserted_primary_key(self):
|
||
|
|
"""Return the primary key for the row just inserted.
|
||
|
|
|
||
|
|
The return value is a list of scalar values
|
||
|
|
corresponding to the list of primary key columns
|
||
|
|
in the target table.
|
||
|
|
|
||
|
|
This only applies to single row :func:`.insert`
|
||
|
|
constructs which did not explicitly specify
|
||
|
|
:meth:`.Insert.returning`.
|
||
|
|
|
||
|
|
Note that primary key columns which specify a
|
||
|
|
server_default clause,
|
||
|
|
or otherwise do not qualify as "autoincrement"
|
||
|
|
columns (see the notes at :class:`.Column`), and were
|
||
|
|
generated using the database-side default, will
|
||
|
|
appear in this list as ``None`` unless the backend
|
||
|
|
supports "returning" and the insert statement executed
|
||
|
|
with the "implicit returning" enabled.
|
||
|
|
|
||
|
|
Raises :class:`~sqlalchemy.exc.InvalidRequestError` if the executed
|
||
|
|
statement is not a compiled expression construct
|
||
|
|
or is not an insert() construct.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
if not self.context.compiled:
|
||
|
|
raise exc.InvalidRequestError(
|
||
|
|
"Statement is not a compiled " "expression construct."
|
||
|
|
)
|
||
|
|
elif not self.context.isinsert:
|
||
|
|
raise exc.InvalidRequestError(
|
||
|
|
"Statement is not an insert() " "expression construct."
|
||
|
|
)
|
||
|
|
elif self.context._is_explicit_returning:
|
||
|
|
raise exc.InvalidRequestError(
|
||
|
|
"Can't call inserted_primary_key "
|
||
|
|
"when returning() "
|
||
|
|
"is used."
|
||
|
|
)
|
||
|
|
|
||
|
|
return self.context.inserted_primary_key
|
||
|
|
|
||
|
|
def last_updated_params(self):
|
||
|
|
"""Return the collection of updated parameters from this
|
||
|
|
execution.
|
||
|
|
|
||
|
|
Raises :class:`~sqlalchemy.exc.InvalidRequestError` if the executed
|
||
|
|
statement is not a compiled expression construct
|
||
|
|
or is not an update() construct.
|
||
|
|
|
||
|
|
"""
|
||
|
|
if not self.context.compiled:
|
||
|
|
raise exc.InvalidRequestError(
|
||
|
|
"Statement is not a compiled " "expression construct."
|
||
|
|
)
|
||
|
|
elif not self.context.isupdate:
|
||
|
|
raise exc.InvalidRequestError(
|
||
|
|
"Statement is not an update() " "expression construct."
|
||
|
|
)
|
||
|
|
elif self.context.executemany:
|
||
|
|
return self.context.compiled_parameters
|
||
|
|
else:
|
||
|
|
return self.context.compiled_parameters[0]
|
||
|
|
|
||
|
|
def last_inserted_params(self):
|
||
|
|
"""Return the collection of inserted parameters from this
|
||
|
|
execution.
|
||
|
|
|
||
|
|
Raises :class:`~sqlalchemy.exc.InvalidRequestError` if the executed
|
||
|
|
statement is not a compiled expression construct
|
||
|
|
or is not an insert() construct.
|
||
|
|
|
||
|
|
"""
|
||
|
|
if not self.context.compiled:
|
||
|
|
raise exc.InvalidRequestError(
|
||
|
|
"Statement is not a compiled " "expression construct."
|
||
|
|
)
|
||
|
|
elif not self.context.isinsert:
|
||
|
|
raise exc.InvalidRequestError(
|
||
|
|
"Statement is not an insert() " "expression construct."
|
||
|
|
)
|
||
|
|
elif self.context.executemany:
|
||
|
|
return self.context.compiled_parameters
|
||
|
|
else:
|
||
|
|
return self.context.compiled_parameters[0]
|
||
|
|
|
||
|
|
@property
|
||
|
|
def returned_defaults(self):
|
||
|
|
"""Return the values of default columns that were fetched using
|
||
|
|
the :meth:`.ValuesBase.return_defaults` feature.
|
||
|
|
|
||
|
|
The value is an instance of :class:`.RowProxy`, or ``None``
|
||
|
|
if :meth:`.ValuesBase.return_defaults` was not used or if the
|
||
|
|
backend does not support RETURNING.
|
||
|
|
|
||
|
|
.. versionadded:: 0.9.0
|
||
|
|
|
||
|
|
.. seealso::
|
||
|
|
|
||
|
|
:meth:`.ValuesBase.return_defaults`
|
||
|
|
|
||
|
|
"""
|
||
|
|
return self.context.returned_defaults
|
||
|
|
|
||
|
|
def lastrow_has_defaults(self):
|
||
|
|
"""Return ``lastrow_has_defaults()`` from the underlying
|
||
|
|
:class:`.ExecutionContext`.
|
||
|
|
|
||
|
|
See :class:`.ExecutionContext` for details.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
return self.context.lastrow_has_defaults()
|
||
|
|
|
||
|
|
def postfetch_cols(self):
|
||
|
|
"""Return ``postfetch_cols()`` from the underlying
|
||
|
|
:class:`.ExecutionContext`.
|
||
|
|
|
||
|
|
See :class:`.ExecutionContext` for details.
|
||
|
|
|
||
|
|
Raises :class:`~sqlalchemy.exc.InvalidRequestError` if the executed
|
||
|
|
statement is not a compiled expression construct
|
||
|
|
or is not an insert() or update() construct.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
if not self.context.compiled:
|
||
|
|
raise exc.InvalidRequestError(
|
||
|
|
"Statement is not a compiled " "expression construct."
|
||
|
|
)
|
||
|
|
elif not self.context.isinsert and not self.context.isupdate:
|
||
|
|
raise exc.InvalidRequestError(
|
||
|
|
"Statement is not an insert() or update() "
|
||
|
|
"expression construct."
|
||
|
|
)
|
||
|
|
return self.context.postfetch_cols
|
||
|
|
|
||
|
|
def prefetch_cols(self):
|
||
|
|
"""Return ``prefetch_cols()`` from the underlying
|
||
|
|
:class:`.ExecutionContext`.
|
||
|
|
|
||
|
|
See :class:`.ExecutionContext` for details.
|
||
|
|
|
||
|
|
Raises :class:`~sqlalchemy.exc.InvalidRequestError` if the executed
|
||
|
|
statement is not a compiled expression construct
|
||
|
|
or is not an insert() or update() construct.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
if not self.context.compiled:
|
||
|
|
raise exc.InvalidRequestError(
|
||
|
|
"Statement is not a compiled " "expression construct."
|
||
|
|
)
|
||
|
|
elif not self.context.isinsert and not self.context.isupdate:
|
||
|
|
raise exc.InvalidRequestError(
|
||
|
|
"Statement is not an insert() or update() "
|
||
|
|
"expression construct."
|
||
|
|
)
|
||
|
|
return self.context.prefetch_cols
|
||
|
|
|
||
|
|
def supports_sane_rowcount(self):
|
||
|
|
"""Return ``supports_sane_rowcount`` from the dialect.
|
||
|
|
|
||
|
|
See :attr:`.ResultProxy.rowcount` for background.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
return self.dialect.supports_sane_rowcount
|
||
|
|
|
||
|
|
def supports_sane_multi_rowcount(self):
|
||
|
|
"""Return ``supports_sane_multi_rowcount`` from the dialect.
|
||
|
|
|
||
|
|
See :attr:`.ResultProxy.rowcount` for background.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
return self.dialect.supports_sane_multi_rowcount
|
||
|
|
|
||
|
|
def _fetchone_impl(self):
|
||
|
|
try:
|
||
|
|
return self.cursor.fetchone()
|
||
|
|
except AttributeError:
|
||
|
|
return self._non_result(None)
|
||
|
|
|
||
|
|
def _fetchmany_impl(self, size=None):
|
||
|
|
try:
|
||
|
|
if size is None:
|
||
|
|
return self.cursor.fetchmany()
|
||
|
|
else:
|
||
|
|
return self.cursor.fetchmany(size)
|
||
|
|
except AttributeError:
|
||
|
|
return self._non_result([])
|
||
|
|
|
||
|
|
def _fetchall_impl(self):
|
||
|
|
try:
|
||
|
|
return self.cursor.fetchall()
|
||
|
|
except AttributeError:
|
||
|
|
return self._non_result([])
|
||
|
|
|
||
|
|
def _non_result(self, default):
|
||
|
|
if self._metadata is None:
|
||
|
|
raise exc.ResourceClosedError(
|
||
|
|
"This result object does not return rows. "
|
||
|
|
"It has been closed automatically."
|
||
|
|
)
|
||
|
|
elif self.closed:
|
||
|
|
raise exc.ResourceClosedError("This result object is closed.")
|
||
|
|
else:
|
||
|
|
return default
|
||
|
|
|
||
|
|
def process_rows(self, rows):
|
||
|
|
process_row = self._process_row
|
||
|
|
metadata = self._metadata
|
||
|
|
keymap = metadata._keymap
|
||
|
|
processors = metadata._processors
|
||
|
|
if self._echo:
|
||
|
|
log = self.context.engine.logger.debug
|
||
|
|
l = []
|
||
|
|
for row in rows:
|
||
|
|
log("Row %r", sql_util._repr_row(row))
|
||
|
|
l.append(process_row(metadata, row, processors, keymap))
|
||
|
|
return l
|
||
|
|
else:
|
||
|
|
return [
|
||
|
|
process_row(metadata, row, processors, keymap) for row in rows
|
||
|
|
]
|
||
|
|
|
||
|
|
def fetchall(self):
|
||
|
|
"""Fetch all rows, just like DB-API ``cursor.fetchall()``.
|
||
|
|
|
||
|
|
After all rows have been exhausted, the underlying DBAPI
|
||
|
|
cursor resource is released, and the object may be safely
|
||
|
|
discarded.
|
||
|
|
|
||
|
|
Subsequent calls to :meth:`.ResultProxy.fetchall` will return
|
||
|
|
an empty list. After the :meth:`.ResultProxy.close` method is
|
||
|
|
called, the method will raise :class:`.ResourceClosedError`.
|
||
|
|
|
||
|
|
.. versionchanged:: 1.0.0 - Added "soft close" behavior which
|
||
|
|
allows the result to be used in an "exhausted" state prior to
|
||
|
|
calling the :meth:`.ResultProxy.close` method.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
try:
|
||
|
|
l = self.process_rows(self._fetchall_impl())
|
||
|
|
self._soft_close()
|
||
|
|
return l
|
||
|
|
except BaseException as e:
|
||
|
|
self.connection._handle_dbapi_exception(
|
||
|
|
e, None, None, self.cursor, self.context
|
||
|
|
)
|
||
|
|
|
||
|
|
def fetchmany(self, size=None):
|
||
|
|
"""Fetch many rows, just like DB-API
|
||
|
|
``cursor.fetchmany(size=cursor.arraysize)``.
|
||
|
|
|
||
|
|
After all rows have been exhausted, the underlying DBAPI
|
||
|
|
cursor resource is released, and the object may be safely
|
||
|
|
discarded.
|
||
|
|
|
||
|
|
Calls to :meth:`.ResultProxy.fetchmany` after all rows have been
|
||
|
|
exhausted will return
|
||
|
|
an empty list. After the :meth:`.ResultProxy.close` method is
|
||
|
|
called, the method will raise :class:`.ResourceClosedError`.
|
||
|
|
|
||
|
|
.. versionchanged:: 1.0.0 - Added "soft close" behavior which
|
||
|
|
allows the result to be used in an "exhausted" state prior to
|
||
|
|
calling the :meth:`.ResultProxy.close` method.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
try:
|
||
|
|
l = self.process_rows(self._fetchmany_impl(size))
|
||
|
|
if len(l) == 0:
|
||
|
|
self._soft_close()
|
||
|
|
return l
|
||
|
|
except BaseException as e:
|
||
|
|
self.connection._handle_dbapi_exception(
|
||
|
|
e, None, None, self.cursor, self.context
|
||
|
|
)
|
||
|
|
|
||
|
|
def fetchone(self):
|
||
|
|
"""Fetch one row, just like DB-API ``cursor.fetchone()``.
|
||
|
|
|
||
|
|
After all rows have been exhausted, the underlying DBAPI
|
||
|
|
cursor resource is released, and the object may be safely
|
||
|
|
discarded.
|
||
|
|
|
||
|
|
Calls to :meth:`.ResultProxy.fetchone` after all rows have
|
||
|
|
been exhausted will return ``None``.
|
||
|
|
After the :meth:`.ResultProxy.close` method is
|
||
|
|
called, the method will raise :class:`.ResourceClosedError`.
|
||
|
|
|
||
|
|
.. versionchanged:: 1.0.0 - Added "soft close" behavior which
|
||
|
|
allows the result to be used in an "exhausted" state prior to
|
||
|
|
calling the :meth:`.ResultProxy.close` method.
|
||
|
|
|
||
|
|
"""
|
||
|
|
try:
|
||
|
|
row = self._fetchone_impl()
|
||
|
|
if row is not None:
|
||
|
|
return self.process_rows([row])[0]
|
||
|
|
else:
|
||
|
|
self._soft_close()
|
||
|
|
return None
|
||
|
|
except BaseException as e:
|
||
|
|
self.connection._handle_dbapi_exception(
|
||
|
|
e, None, None, self.cursor, self.context
|
||
|
|
)
|
||
|
|
|
||
|
|
def first(self):
|
||
|
|
"""Fetch the first row and then close the result set unconditionally.
|
||
|
|
|
||
|
|
Returns None if no row is present.
|
||
|
|
|
||
|
|
After calling this method, the object is fully closed,
|
||
|
|
e.g. the :meth:`.ResultProxy.close` method will have been called.
|
||
|
|
|
||
|
|
"""
|
||
|
|
if self._metadata is None:
|
||
|
|
return self._non_result(None)
|
||
|
|
|
||
|
|
try:
|
||
|
|
row = self._fetchone_impl()
|
||
|
|
except BaseException as e:
|
||
|
|
self.connection._handle_dbapi_exception(
|
||
|
|
e, None, None, self.cursor, self.context
|
||
|
|
)
|
||
|
|
|
||
|
|
try:
|
||
|
|
if row is not None:
|
||
|
|
return self.process_rows([row])[0]
|
||
|
|
else:
|
||
|
|
return None
|
||
|
|
finally:
|
||
|
|
self.close()
|
||
|
|
|
||
|
|
def scalar(self):
|
||
|
|
"""Fetch the first column of the first row, and close the result set.
|
||
|
|
|
||
|
|
Returns None if no row is present.
|
||
|
|
|
||
|
|
After calling this method, the object is fully closed,
|
||
|
|
e.g. the :meth:`.ResultProxy.close` method will have been called.
|
||
|
|
|
||
|
|
"""
|
||
|
|
row = self.first()
|
||
|
|
if row is not None:
|
||
|
|
return row[0]
|
||
|
|
else:
|
||
|
|
return None
|
||
|
|
|
||
|
|
|
||
|
|
class BufferedRowResultProxy(ResultProxy):
|
||
|
|
"""A ResultProxy with row buffering behavior.
|
||
|
|
|
||
|
|
``ResultProxy`` that buffers the contents of a selection of rows
|
||
|
|
before ``fetchone()`` is called. This is to allow the results of
|
||
|
|
``cursor.description`` to be available immediately, when
|
||
|
|
interfacing with a DB-API that requires rows to be consumed before
|
||
|
|
this information is available (currently psycopg2, when used with
|
||
|
|
server-side cursors).
|
||
|
|
|
||
|
|
The pre-fetching behavior fetches only one row initially, and then
|
||
|
|
grows its buffer size by a fixed amount with each successive need
|
||
|
|
for additional rows up to a size of 1000.
|
||
|
|
|
||
|
|
The size argument is configurable using the ``max_row_buffer``
|
||
|
|
execution option::
|
||
|
|
|
||
|
|
with psycopg2_engine.connect() as conn:
|
||
|
|
|
||
|
|
result = conn.execution_options(
|
||
|
|
stream_results=True, max_row_buffer=50
|
||
|
|
).execute("select * from table")
|
||
|
|
|
||
|
|
.. versionadded:: 1.0.6 Added the ``max_row_buffer`` option.
|
||
|
|
|
||
|
|
.. seealso::
|
||
|
|
|
||
|
|
:ref:`psycopg2_execution_options`
|
||
|
|
"""
|
||
|
|
|
||
|
|
def _init_metadata(self):
|
||
|
|
self._max_row_buffer = self.context.execution_options.get(
|
||
|
|
"max_row_buffer", None
|
||
|
|
)
|
||
|
|
self.__buffer_rows()
|
||
|
|
super(BufferedRowResultProxy, self)._init_metadata()
|
||
|
|
|
||
|
|
# this is a "growth chart" for the buffering of rows.
|
||
|
|
# each successive __buffer_rows call will use the next
|
||
|
|
# value in the list for the buffer size until the max
|
||
|
|
# is reached
|
||
|
|
size_growth = {
|
||
|
|
1: 5,
|
||
|
|
5: 10,
|
||
|
|
10: 20,
|
||
|
|
20: 50,
|
||
|
|
50: 100,
|
||
|
|
100: 250,
|
||
|
|
250: 500,
|
||
|
|
500: 1000,
|
||
|
|
}
|
||
|
|
|
||
|
|
def __buffer_rows(self):
|
||
|
|
if self.cursor is None:
|
||
|
|
return
|
||
|
|
size = getattr(self, "_bufsize", 1)
|
||
|
|
self.__rowbuffer = collections.deque(self.cursor.fetchmany(size))
|
||
|
|
self._bufsize = self.size_growth.get(size, size)
|
||
|
|
if self._max_row_buffer is not None:
|
||
|
|
self._bufsize = min(self._max_row_buffer, self._bufsize)
|
||
|
|
|
||
|
|
def _soft_close(self, **kw):
|
||
|
|
self.__rowbuffer.clear()
|
||
|
|
super(BufferedRowResultProxy, self)._soft_close(**kw)
|
||
|
|
|
||
|
|
def _fetchone_impl(self):
|
||
|
|
if self.cursor is None:
|
||
|
|
return self._non_result(None)
|
||
|
|
if not self.__rowbuffer:
|
||
|
|
self.__buffer_rows()
|
||
|
|
if not self.__rowbuffer:
|
||
|
|
return None
|
||
|
|
return self.__rowbuffer.popleft()
|
||
|
|
|
||
|
|
def _fetchmany_impl(self, size=None):
|
||
|
|
if size is None:
|
||
|
|
return self._fetchall_impl()
|
||
|
|
result = []
|
||
|
|
for x in range(0, size):
|
||
|
|
row = self._fetchone_impl()
|
||
|
|
if row is None:
|
||
|
|
break
|
||
|
|
result.append(row)
|
||
|
|
return result
|
||
|
|
|
||
|
|
def _fetchall_impl(self):
|
||
|
|
if self.cursor is None:
|
||
|
|
return self._non_result([])
|
||
|
|
self.__rowbuffer.extend(self.cursor.fetchall())
|
||
|
|
ret = self.__rowbuffer
|
||
|
|
self.__rowbuffer = collections.deque()
|
||
|
|
return ret
|
||
|
|
|
||
|
|
|
||
|
|
class FullyBufferedResultProxy(ResultProxy):
|
||
|
|
"""A result proxy that buffers rows fully upon creation.
|
||
|
|
|
||
|
|
Used for operations where a result is to be delivered
|
||
|
|
after the database conversation can not be continued,
|
||
|
|
such as MSSQL INSERT...OUTPUT after an autocommit.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def _init_metadata(self):
|
||
|
|
super(FullyBufferedResultProxy, self)._init_metadata()
|
||
|
|
self.__rowbuffer = self._buffer_rows()
|
||
|
|
|
||
|
|
def _buffer_rows(self):
|
||
|
|
return collections.deque(self.cursor.fetchall())
|
||
|
|
|
||
|
|
def _soft_close(self, **kw):
|
||
|
|
self.__rowbuffer.clear()
|
||
|
|
super(FullyBufferedResultProxy, self)._soft_close(**kw)
|
||
|
|
|
||
|
|
def _fetchone_impl(self):
|
||
|
|
if self.__rowbuffer:
|
||
|
|
return self.__rowbuffer.popleft()
|
||
|
|
else:
|
||
|
|
return self._non_result(None)
|
||
|
|
|
||
|
|
def _fetchmany_impl(self, size=None):
|
||
|
|
if size is None:
|
||
|
|
return self._fetchall_impl()
|
||
|
|
result = []
|
||
|
|
for x in range(0, size):
|
||
|
|
row = self._fetchone_impl()
|
||
|
|
if row is None:
|
||
|
|
break
|
||
|
|
result.append(row)
|
||
|
|
return result
|
||
|
|
|
||
|
|
def _fetchall_impl(self):
|
||
|
|
if not self.cursor:
|
||
|
|
return self._non_result([])
|
||
|
|
ret = self.__rowbuffer
|
||
|
|
self.__rowbuffer = collections.deque()
|
||
|
|
return ret
|
||
|
|
|
||
|
|
|
||
|
|
class BufferedColumnRow(RowProxy):
|
||
|
|
def __init__(self, parent, row, processors, keymap):
|
||
|
|
# preprocess row
|
||
|
|
row = list(row)
|
||
|
|
# this is a tad faster than using enumerate
|
||
|
|
index = 0
|
||
|
|
for processor in parent._orig_processors:
|
||
|
|
if processor is not None:
|
||
|
|
row[index] = processor(row[index])
|
||
|
|
index += 1
|
||
|
|
row = tuple(row)
|
||
|
|
super(BufferedColumnRow, self).__init__(
|
||
|
|
parent, row, processors, keymap
|
||
|
|
)
|
||
|
|
|
||
|
|
|
||
|
|
class BufferedColumnResultProxy(ResultProxy):
|
||
|
|
"""A ResultProxy with column buffering behavior.
|
||
|
|
|
||
|
|
``ResultProxy`` that loads all columns into memory each time
|
||
|
|
fetchone() is called. If fetchmany() or fetchall() are called,
|
||
|
|
the full grid of results is fetched. This is to operate with
|
||
|
|
databases where result rows contain "live" results that fall out
|
||
|
|
of scope unless explicitly fetched.
|
||
|
|
|
||
|
|
.. versionchanged:: 1.2 This :class:`.ResultProxy` is not used by
|
||
|
|
any SQLAlchemy-included dialects.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
_process_row = BufferedColumnRow
|
||
|
|
|
||
|
|
def _init_metadata(self):
|
||
|
|
super(BufferedColumnResultProxy, self)._init_metadata()
|
||
|
|
|
||
|
|
metadata = self._metadata
|
||
|
|
|
||
|
|
# don't double-replace the processors, in the case
|
||
|
|
# of a cached ResultMetaData
|
||
|
|
if metadata._orig_processors is None:
|
||
|
|
# orig_processors will be used to preprocess each row when
|
||
|
|
# they are constructed.
|
||
|
|
metadata._orig_processors = metadata._processors
|
||
|
|
# replace the all type processors by None processors.
|
||
|
|
metadata._processors = [None for _ in range(len(metadata.keys))]
|
||
|
|
keymap = {}
|
||
|
|
for k, (func, obj, index) in metadata._keymap.items():
|
||
|
|
keymap[k] = (None, obj, index)
|
||
|
|
metadata._keymap = keymap
|
||
|
|
|
||
|
|
def fetchall(self):
|
||
|
|
# can't call cursor.fetchall(), since rows must be
|
||
|
|
# fully processed before requesting more from the DBAPI.
|
||
|
|
l = []
|
||
|
|
while True:
|
||
|
|
row = self.fetchone()
|
||
|
|
if row is None:
|
||
|
|
break
|
||
|
|
l.append(row)
|
||
|
|
return l
|
||
|
|
|
||
|
|
def fetchmany(self, size=None):
|
||
|
|
# can't call cursor.fetchmany(), since rows must be
|
||
|
|
# fully processed before requesting more from the DBAPI.
|
||
|
|
if size is None:
|
||
|
|
return self.fetchall()
|
||
|
|
l = []
|
||
|
|
for i in range(size):
|
||
|
|
row = self.fetchone()
|
||
|
|
if row is None:
|
||
|
|
break
|
||
|
|
l.append(row)
|
||
|
|
return l
|