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# ported from:
# https://github.com/aio-libs/aiopg/blob/master/aiopg/sa/result.py
import weakref
from collections.abc import Mapping, Sequence
from sqlalchemy.sql import expression, sqltypes
from . import exc
async def create_result_proxy(connection, cursor, dialect, result_map):
result_proxy = ResultProxy(connection, cursor, dialect, result_map)
await result_proxy._prepare()
return result_proxy
class RowProxy(Mapping):
__slots__ = ('_result_proxy', '_row', '_processors', '_keymap')
def __init__(self, result_proxy, row, processors, keymap):
"""RowProxy objects are constructed by ResultProxy objects."""
self._result_proxy = result_proxy
self._row = row
self._processors = processors
self._keymap = keymap
def __iter__(self):
return iter(self._result_proxy.keys)
def __len__(self):
return len(self._row)
def __getitem__(self, key):
try:
processor, obj, index = self._keymap[key]
except KeyError:
processor, obj, index = self._result_proxy._key_fallback(key)
# Do we need slicing at all? RowProxy now is Mapping not Sequence
# except TypeError:
# if isinstance(key, slice):
# l = []
# for processor, value in zip(self._processors[key],
# self._row[key]):
# if processor is None:
# l.append(value)
# else:
# l.append(processor(value))
# return tuple(l)
# else:
# raise
if index is None:
raise exc.InvalidRequestError(
"Ambiguous column name '%s' in result set! "
"try 'use_labels' option on select statement." % key)
if processor is not None:
return processor(self._row[index])
else:
return self._row[index]
def __getattr__(self, name):
try:
return self[name]
except KeyError as e:
raise AttributeError(e.args[0])
def __contains__(self, key):
return self._result_proxy._has_key(self._row, key)
__hash__ = None
def __eq__(self, other):
if isinstance(other, RowProxy):
return self.as_tuple() == other.as_tuple()
elif isinstance(other, Sequence):
return self.as_tuple() == other
else:
return NotImplemented
def __ne__(self, other):
return not self == other
def as_tuple(self):
return tuple(self[k] for k in self)
def __repr__(self):
return repr(self.as_tuple())
class ResultMetaData:
"""Handle cursor.description, applying additional info from an execution
context."""
def __init__(self, result_proxy, metadata):
self._processors = processors = []
result_map = {}
if result_proxy._result_map:
result_map = {elem[0]: elem[3] for elem in
result_proxy._result_map}
# We do not strictly need to store the processor in the key mapping,
# though it is faster in the Python version (probably because of the
# saved attribute lookup self._processors)
self._keymap = keymap = {}
self.keys = []
dialect = result_proxy.dialect
# `dbapi_type_map` property removed in SQLAlchemy 1.2+.
# Usage of `getattr` only needed for backward compatibility with
# older versions of SQLAlchemy.
typemap = getattr(dialect, 'dbapi_type_map', {})
assert dialect.case_sensitive, \
"Doesn't support case insensitive database connection"
# high precedence key values.
primary_keymap = {}
assert not dialect.description_encoding, \
"psycopg in py3k should not use this"
for i, rec in enumerate(metadata):
colname = rec[0]
coltype = rec[1]
# PostgreSQL doesn't require this.
# if dialect.requires_name_normalize:
# colname = dialect.normalize_name(colname)
name, obj, type_ = (
colname,
None,
result_map.get(
colname,
typemap.get(coltype, sqltypes.NULLTYPE))
)
processor = type_._cached_result_processor(dialect, coltype)
processors.append(processor)
rec = (processor, obj, i)
# indexes as keys. This is only needed for the Python version of
# RowProxy (the C version uses a faster path for integer indexes).
primary_keymap[i] = rec
# populate primary keymap, looking for conflicts.
if primary_keymap.setdefault(name, rec) is not rec:
# place a record that doesn't have the "index" - this
# is interpreted later as an AmbiguousColumnError,
# but only when actually accessed. Columns
# colliding by name is not a problem if those names
# aren't used; integer access is always
# unambiguous.
primary_keymap[name] = rec = (None, obj, None)
self.keys.append(colname)
if obj:
for o in obj:
keymap[o] = rec
# technically we should be doing this but we
# are saving on callcounts by not doing so.
# if keymap.setdefault(o, rec) is not rec:
# keymap[o] = (None, obj, None)
# overwrite keymap values with those of the
# high precedence keymap.
keymap.update(primary_keymap)
def _key_fallback(self, key, raiseerr=True):
map = self._keymap
result = None
if isinstance(key, str):
result = map.get(key)
# 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 in map):
result = map[key._label]
elif (hasattr(key, 'name') and key.name in map):
# match is only on name.
result = map[key.name]
# 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, row, key):
if key in self._keymap:
return True
else:
return self._key_fallback(key, False) is not None
class ResultProxy:
"""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 sqlalchemy 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 sqlalchemy TypeEngine objects, which are referenced from
the originating SQL statement that produced this result set.
"""
def __init__(self, connection, cursor, dialect, result_map):
self._dialect = dialect
self._closed = False
self._cursor = cursor
self._connection = connection
self._rowcount = cursor.rowcount
self._lastrowid = cursor.lastrowid
self._result_map = result_map
async def _prepare(self):
loop = self._connection.connection.loop
cursor = self._cursor
if cursor.description is not None:
self._metadata = ResultMetaData(self, cursor.description)
def callback(wr):
loop.create_task(cursor.close())
self._weak = weakref.ref(self, callback)
else:
self._metadata = None
await self.close()
self._weak = None
@property
def dialect(self):
"""SQLAlchemy dialect."""
return self._dialect
@property
def cursor(self):
return self._cursor
def keys(self):
"""Return the current set of string keys for rows."""
if self._metadata:
return tuple(self._metadata.keys)
else:
return ()
@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 .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.
* .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.
* Statements that use RETURNING may not return a correct
rowcount.
"""
return self._rowcount
@property
def lastrowid(self):
"""Returns 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.
"""
return self._lastrowid
@property
def returns_rows(self):
"""True if this ResultProxy returns rows.
I.e. if it is legal to call the methods .fetchone(),
.fetchmany() and .fetchall()`.
"""
return self._metadata is not None
@property
def closed(self):
return self._closed
async def close(self):
"""Close this ResultProxy.
Closes the underlying DBAPI cursor corresponding to the execution.
Note that any data cached within this ResultProxy is still available.
For some types of results, this may include buffered rows.
If this ResultProxy was generated from an implicit execution,
the underlying Connection will also be closed (returns the
underlying DBAPI connection to the connection pool.)
This method is called automatically when:
* all result rows are exhausted using the fetchXXX() methods.
* cursor.description is None.
"""
if not self._closed:
self._closed = True
await self._cursor.close()
# allow consistent errors
self._cursor = None
self._weak = None
# def __iter__(self):
# while True:
# row = yield from self.fetchone()
# if row is None:
# raise StopIteration
# else:
# yield row
def _non_result(self):
if self._metadata is None:
raise exc.ResourceClosedError(
"This result object does not return rows. "
"It has been closed automatically.")
else:
raise exc.ResourceClosedError("This result object is closed.")
def _process_rows(self, rows):
process_row = RowProxy
metadata = self._metadata
keymap = metadata._keymap
processors = metadata._processors
return [process_row(metadata, row, processors, keymap)
for row in rows]
async def fetchall(self):
"""Fetch all rows, just like DB-API cursor.fetchall()."""
try:
rows = await self._cursor.fetchall()
except AttributeError:
self._non_result()
else:
ret = self._process_rows(rows)
await self.close()
return ret
async def fetchone(self):
"""Fetch one row, just like DB-API cursor.fetchone().
If a row is present, the cursor remains open after this is called.
Else the cursor is automatically closed and None is returned.
"""
try:
row = await self._cursor.fetchone()
except AttributeError:
self._non_result()
else:
if row is not None:
return self._process_rows([row])[0]
else:
await self.close()
return None
async def fetchmany(self, size=None):
"""Fetch many rows, just like DB-API
cursor.fetchmany(size=cursor.arraysize).
If rows are present, the cursor remains open after this is called.
Else the cursor is automatically closed and an empty list is returned.
"""
try:
if size is None:
rows = await self._cursor.fetchmany()
else:
rows = await self._cursor.fetchmany(size)
except AttributeError:
self._non_result()
else:
ret = self._process_rows(rows)
if len(ret) == 0:
await self.close()
return ret
async def first(self):
"""Fetch the first row and then close the result set unconditionally.
Returns None if no row is present.
"""
if self._metadata is None:
self._non_result()
try:
return (await self.fetchone())
finally:
await self.close()
async def scalar(self):
"""Fetch the first column of the first row, and close the result set.
Returns None if no row is present.
"""
row = await self.first()
if row is not None:
return row[0]
else:
return None
def __aiter__(self):
return self
async def __anext__(self):
data = await self.fetchone()
if data is not None:
return data
else:
raise StopAsyncIteration # noqa
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