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922 lines
30 KiB
Python
922 lines
30 KiB
Python
# sql/util.py
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# Copyright (C) 2005-2013 the SQLAlchemy authors and contributors <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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from .. import exc, schema, util, sql
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from ..util import topological
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from . import expression, operators, visitors
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from itertools import chain
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from collections import deque
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"""Utility functions that build upon SQL and Schema constructs."""
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def sort_tables(tables, skip_fn=None, extra_dependencies=None):
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"""sort a collection of Table objects in order of
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their foreign-key dependency."""
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tables = list(tables)
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tuples = []
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if extra_dependencies is not None:
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tuples.extend(extra_dependencies)
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def visit_foreign_key(fkey):
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if fkey.use_alter:
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return
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elif skip_fn and skip_fn(fkey):
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return
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parent_table = fkey.column.table
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if parent_table in tables:
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child_table = fkey.parent.table
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if parent_table is not child_table:
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tuples.append((parent_table, child_table))
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for table in tables:
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visitors.traverse(table,
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{'schema_visitor': True},
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{'foreign_key': visit_foreign_key})
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tuples.extend(
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[parent, table] for parent in table._extra_dependencies
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)
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return list(topological.sort(tuples, tables))
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def find_join_source(clauses, join_to):
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"""Given a list of FROM clauses and a selectable,
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return the first index and element from the list of
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clauses which can be joined against the selectable. returns
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None, None if no match is found.
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e.g.::
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clause1 = table1.join(table2)
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clause2 = table4.join(table5)
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join_to = table2.join(table3)
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find_join_source([clause1, clause2], join_to) == clause1
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"""
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selectables = list(expression._from_objects(join_to))
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for i, f in enumerate(clauses):
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for s in selectables:
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if f.is_derived_from(s):
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return i, f
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else:
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return None, None
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def visit_binary_product(fn, expr):
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"""Produce a traversal of the given expression, delivering
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column comparisons to the given function.
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The function is of the form::
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def my_fn(binary, left, right)
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For each binary expression located which has a
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comparison operator, the product of "left" and
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"right" will be delivered to that function,
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in terms of that binary.
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Hence an expression like::
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and_(
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(a + b) == q + func.sum(e + f),
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j == r
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)
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would have the traversal::
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a <eq> q
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a <eq> e
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a <eq> f
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b <eq> q
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b <eq> e
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b <eq> f
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j <eq> r
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That is, every combination of "left" and
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"right" that doesn't further contain
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a binary comparison is passed as pairs.
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"""
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stack = []
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def visit(element):
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if isinstance(element, (expression.ScalarSelect)):
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# we dont want to dig into correlated subqueries,
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# those are just column elements by themselves
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yield element
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elif element.__visit_name__ == 'binary' and \
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operators.is_comparison(element.operator):
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stack.insert(0, element)
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for l in visit(element.left):
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for r in visit(element.right):
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fn(stack[0], l, r)
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stack.pop(0)
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for elem in element.get_children():
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visit(elem)
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else:
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if isinstance(element, expression.ColumnClause):
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yield element
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for elem in element.get_children():
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for e in visit(elem):
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yield e
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list(visit(expr))
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def find_tables(clause, check_columns=False,
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include_aliases=False, include_joins=False,
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include_selects=False, include_crud=False):
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"""locate Table objects within the given expression."""
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tables = []
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_visitors = {}
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if include_selects:
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_visitors['select'] = _visitors['compound_select'] = tables.append
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if include_joins:
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_visitors['join'] = tables.append
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if include_aliases:
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_visitors['alias'] = tables.append
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if include_crud:
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_visitors['insert'] = _visitors['update'] = \
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_visitors['delete'] = lambda ent: tables.append(ent.table)
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if check_columns:
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def visit_column(column):
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tables.append(column.table)
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_visitors['column'] = visit_column
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_visitors['table'] = tables.append
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visitors.traverse(clause, {'column_collections': False}, _visitors)
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return tables
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def find_columns(clause):
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"""locate Column objects within the given expression."""
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cols = util.column_set()
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visitors.traverse(clause, {}, {'column': cols.add})
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return cols
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def unwrap_order_by(clause):
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"""Break up an 'order by' expression into individual column-expressions,
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without DESC/ASC/NULLS FIRST/NULLS LAST"""
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cols = util.column_set()
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stack = deque([clause])
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while stack:
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t = stack.popleft()
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if isinstance(t, expression.ColumnElement) and \
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(
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not isinstance(t, expression.UnaryExpression) or \
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not operators.is_ordering_modifier(t.modifier)
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):
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cols.add(t)
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else:
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for c in t.get_children():
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stack.append(c)
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return cols
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def clause_is_present(clause, search):
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"""Given a target clause and a second to search within, return True
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if the target is plainly present in the search without any
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subqueries or aliases involved.
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Basically descends through Joins.
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"""
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stack = [search]
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while stack:
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elem = stack.pop()
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if clause == elem: # use == here so that Annotated's compare
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return True
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elif isinstance(elem, expression.Join):
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stack.extend((elem.left, elem.right))
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return False
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def bind_values(clause):
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"""Return an ordered list of "bound" values in the given clause.
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E.g.::
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>>> expr = and_(
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... table.c.foo==5, table.c.foo==7
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... )
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>>> bind_values(expr)
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[5, 7]
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"""
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v = []
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def visit_bindparam(bind):
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v.append(bind.effective_value)
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visitors.traverse(clause, {}, {'bindparam': visit_bindparam})
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return v
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def _quote_ddl_expr(element):
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if isinstance(element, basestring):
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element = element.replace("'", "''")
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return "'%s'" % element
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else:
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return repr(element)
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class _repr_params(object):
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"""A string view of bound parameters, truncating
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display to the given number of 'multi' parameter sets.
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"""
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def __init__(self, params, batches):
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self.params = params
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self.batches = batches
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def __repr__(self):
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if isinstance(self.params, (list, tuple)) and \
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len(self.params) > self.batches and \
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isinstance(self.params[0], (list, dict, tuple)):
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msg = " ... displaying %i of %i total bound parameter sets ... "
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return ' '.join((
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repr(self.params[:self.batches - 2])[0:-1],
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msg % (self.batches, len(self.params)),
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repr(self.params[-2:])[1:]
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))
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else:
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return repr(self.params)
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def expression_as_ddl(clause):
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"""Given a SQL expression, convert for usage in DDL, such as
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CREATE INDEX and CHECK CONSTRAINT.
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Converts bind params into quoted literals, column identifiers
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into detached column constructs so that the parent table
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identifier is not included.
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.. deprecated:: this function is removed in 0.9.0.
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"""
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def repl(element):
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if isinstance(element, expression.BindParameter):
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return expression.literal_column(_quote_ddl_expr(element.value))
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elif isinstance(element, expression.ColumnClause) and \
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element.table is not None:
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col = expression.column(element.name)
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col.quote = element.quote
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return col
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else:
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return None
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return visitors.replacement_traverse(clause, {}, repl)
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def adapt_criterion_to_null(crit, nulls):
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"""given criterion containing bind params, convert selected elements
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to IS NULL.
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"""
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def visit_binary(binary):
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if isinstance(binary.left, expression.BindParameter) \
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and binary.left._identifying_key in nulls:
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# reverse order if the NULL is on the left side
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binary.left = binary.right
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binary.right = expression.null()
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binary.operator = operators.is_
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binary.negate = operators.isnot
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elif isinstance(binary.right, expression.BindParameter) \
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and binary.right._identifying_key in nulls:
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binary.right = expression.null()
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binary.operator = operators.is_
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binary.negate = operators.isnot
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return visitors.cloned_traverse(crit, {}, {'binary': visit_binary})
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def join_condition(a, b, ignore_nonexistent_tables=False,
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a_subset=None,
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consider_as_foreign_keys=None):
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"""create a join condition between two tables or selectables.
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e.g.::
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join_condition(tablea, tableb)
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would produce an expression along the lines of::
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tablea.c.id==tableb.c.tablea_id
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The join is determined based on the foreign key relationships
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between the two selectables. If there are multiple ways
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to join, or no way to join, an error is raised.
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:param ignore_nonexistent_tables: Deprecated - this
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flag is no longer used. Only resolution errors regarding
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the two given tables are propagated.
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:param a_subset: An optional expression that is a sub-component
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of ``a``. An attempt will be made to join to just this sub-component
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first before looking at the full ``a`` construct, and if found
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will be successful even if there are other ways to join to ``a``.
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This allows the "right side" of a join to be passed thereby
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providing a "natural join".
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"""
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crit = []
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constraints = set()
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for left in (a_subset, a):
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if left is None:
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continue
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for fk in sorted(
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b.foreign_keys,
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key=lambda fk: fk.parent._creation_order):
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if consider_as_foreign_keys is not None and \
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fk.parent not in consider_as_foreign_keys:
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continue
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try:
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col = fk.get_referent(left)
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except exc.NoReferenceError, nrte:
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if nrte.table_name == left.name:
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raise
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else:
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continue
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if col is not None:
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crit.append(col == fk.parent)
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constraints.add(fk.constraint)
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if left is not b:
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for fk in sorted(
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left.foreign_keys,
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key=lambda fk: fk.parent._creation_order):
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if consider_as_foreign_keys is not None and \
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fk.parent not in consider_as_foreign_keys:
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continue
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try:
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col = fk.get_referent(b)
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except exc.NoReferenceError, nrte:
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if nrte.table_name == b.name:
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raise
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else:
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# this is totally covered. can't get
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# coverage to mark it.
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continue
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if col is not None:
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crit.append(col == fk.parent)
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constraints.add(fk.constraint)
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if crit:
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break
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if len(crit) == 0:
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if isinstance(b, expression.FromGrouping):
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hint = " Perhaps you meant to convert the right side to a "\
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"subquery using alias()?"
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else:
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hint = ""
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raise exc.NoForeignKeysError(
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"Can't find any foreign key relationships "
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"between '%s' and '%s'.%s" % (a.description, b.description, hint))
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elif len(constraints) > 1:
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raise exc.AmbiguousForeignKeysError(
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"Can't determine join between '%s' and '%s'; "
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"tables have more than one foreign key "
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"constraint relationship between them. "
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"Please specify the 'onclause' of this "
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"join explicitly." % (a.description, b.description))
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elif len(crit) == 1:
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return (crit[0])
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else:
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return sql.and_(*crit)
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class Annotated(object):
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"""clones a ClauseElement and applies an 'annotations' dictionary.
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Unlike regular clones, this clone also mimics __hash__() and
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__cmp__() of the original element so that it takes its place
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in hashed collections.
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A reference to the original element is maintained, for the important
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reason of keeping its hash value current. When GC'ed, the
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hash value may be reused, causing conflicts.
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"""
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def __new__(cls, *args):
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if not args:
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# clone constructor
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return object.__new__(cls)
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else:
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element, values = args
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# pull appropriate subclass from registry of annotated
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# classes
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try:
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cls = annotated_classes[element.__class__]
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except KeyError:
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cls = annotated_classes[element.__class__] = type.__new__(type,
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"Annotated%s" % element.__class__.__name__,
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(cls, element.__class__), {})
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return object.__new__(cls)
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def __init__(self, element, values):
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# force FromClause to generate their internal
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# collections into __dict__
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if isinstance(element, expression.FromClause):
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element.c
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self.__dict__ = element.__dict__.copy()
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expression.ColumnElement.comparator._reset(self)
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self.__element = element
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self._annotations = values
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def _annotate(self, values):
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_values = self._annotations.copy()
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_values.update(values)
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return self._with_annotations(_values)
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def _with_annotations(self, values):
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clone = self.__class__.__new__(self.__class__)
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clone.__dict__ = self.__dict__.copy()
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expression.ColumnElement.comparator._reset(clone)
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clone._annotations = values
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return clone
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def _deannotate(self, values=None, clone=True):
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if values is None:
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return self.__element
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else:
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_values = self._annotations.copy()
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for v in values:
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_values.pop(v, None)
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return self._with_annotations(_values)
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def _compiler_dispatch(self, visitor, **kw):
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return self.__element.__class__._compiler_dispatch(self, visitor, **kw)
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@property
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def _constructor(self):
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return self.__element._constructor
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def _clone(self):
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clone = self.__element._clone()
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if clone is self.__element:
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# detect immutable, don't change anything
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return self
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else:
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# update the clone with any changes that have occurred
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# to this object's __dict__.
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clone.__dict__.update(self.__dict__)
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return self.__class__(clone, self._annotations)
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def __hash__(self):
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return hash(self.__element)
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def __eq__(self, other):
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if isinstance(self.__element, expression.ColumnOperators):
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return self.__element.__class__.__eq__(self, other)
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else:
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return hash(other) == hash(self)
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|
|
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class AnnotatedColumnElement(Annotated):
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def __init__(self, element, values):
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Annotated.__init__(self, element, values)
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for attr in ('name', 'key', 'table'):
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if self.__dict__.get(attr, False) is None:
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self.__dict__.pop(attr)
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@util.memoized_property
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def name(self):
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"""pull 'name' from parent, if not present"""
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return self._Annotated__element.name
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@util.memoized_property
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def table(self):
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"""pull 'table' from parent, if not present"""
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return self._Annotated__element.table
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@util.memoized_property
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def key(self):
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"""pull 'key' from parent, if not present"""
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return self._Annotated__element.key
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@util.memoized_property
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def info(self):
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return self._Annotated__element.info
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# hard-generate Annotated subclasses. this technique
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# is used instead of on-the-fly types (i.e. type.__new__())
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# so that the resulting objects are pickleable.
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annotated_classes = {}
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for cls in expression.__dict__.values() + [schema.Column, schema.Table]:
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if isinstance(cls, type) and issubclass(cls, expression.ClauseElement):
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if issubclass(cls, expression.ColumnElement):
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annotation_cls = "AnnotatedColumnElement"
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else:
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annotation_cls = "Annotated"
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exec "class Annotated%s(%s, cls):\n" \
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" pass" % (cls.__name__, annotation_cls) in locals()
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exec "annotated_classes[cls] = Annotated%s" % (cls.__name__,)
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|
|
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def _deep_annotate(element, annotations, exclude=None):
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"""Deep copy the given ClauseElement, annotating each element
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with the given annotations dictionary.
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Elements within the exclude collection will be cloned but not annotated.
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"""
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def clone(elem):
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if exclude and \
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hasattr(elem, 'proxy_set') and \
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elem.proxy_set.intersection(exclude):
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newelem = elem._clone()
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elif annotations != elem._annotations:
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newelem = elem._annotate(annotations)
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else:
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newelem = elem
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newelem._copy_internals(clone=clone)
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return newelem
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|
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if element is not None:
|
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element = clone(element)
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return element
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|
|
def _deep_deannotate(element, values=None):
|
|
"""Deep copy the given element, removing annotations."""
|
|
|
|
cloned = util.column_dict()
|
|
|
|
def clone(elem):
|
|
# if a values dict is given,
|
|
# the elem must be cloned each time it appears,
|
|
# as there may be different annotations in source
|
|
# elements that are remaining. if totally
|
|
# removing all annotations, can assume the same
|
|
# slate...
|
|
if values or elem not in cloned:
|
|
newelem = elem._deannotate(values=values, clone=True)
|
|
newelem._copy_internals(clone=clone)
|
|
if not values:
|
|
cloned[elem] = newelem
|
|
return newelem
|
|
else:
|
|
return cloned[elem]
|
|
|
|
if element is not None:
|
|
element = clone(element)
|
|
return element
|
|
|
|
|
|
def _shallow_annotate(element, annotations):
|
|
"""Annotate the given ClauseElement and copy its internals so that
|
|
internal objects refer to the new annotated object.
|
|
|
|
Basically used to apply a "dont traverse" annotation to a
|
|
selectable, without digging throughout the whole
|
|
structure wasting time.
|
|
"""
|
|
element = element._annotate(annotations)
|
|
element._copy_internals()
|
|
return element
|
|
|
|
|
|
def splice_joins(left, right, stop_on=None):
|
|
if left is None:
|
|
return right
|
|
|
|
stack = [(right, None)]
|
|
|
|
adapter = ClauseAdapter(left)
|
|
ret = None
|
|
while stack:
|
|
(right, prevright) = stack.pop()
|
|
if isinstance(right, expression.Join) and right is not stop_on:
|
|
right = right._clone()
|
|
right._reset_exported()
|
|
right.onclause = adapter.traverse(right.onclause)
|
|
stack.append((right.left, right))
|
|
else:
|
|
right = adapter.traverse(right)
|
|
if prevright is not None:
|
|
prevright.left = right
|
|
if ret is None:
|
|
ret = right
|
|
|
|
return ret
|
|
|
|
|
|
def reduce_columns(columns, *clauses, **kw):
|
|
"""given a list of columns, return a 'reduced' set based on natural
|
|
equivalents.
|
|
|
|
the set is reduced to the smallest list of columns which have no natural
|
|
equivalent present in the list. A "natural equivalent" means that two
|
|
columns will ultimately represent the same value because they are related
|
|
by a foreign key.
|
|
|
|
\*clauses is an optional list of join clauses which will be traversed
|
|
to further identify columns that are "equivalent".
|
|
|
|
\**kw may specify 'ignore_nonexistent_tables' to ignore foreign keys
|
|
whose tables are not yet configured, or columns that aren't yet present.
|
|
|
|
This function is primarily used to determine the most minimal "primary key"
|
|
from a selectable, by reducing the set of primary key columns present
|
|
in the the selectable to just those that are not repeated.
|
|
|
|
"""
|
|
ignore_nonexistent_tables = kw.pop('ignore_nonexistent_tables', False)
|
|
only_synonyms = kw.pop('only_synonyms', False)
|
|
|
|
columns = util.ordered_column_set(columns)
|
|
|
|
omit = util.column_set()
|
|
for col in columns:
|
|
for fk in chain(*[c.foreign_keys for c in col.proxy_set]):
|
|
for c in columns:
|
|
if c is col:
|
|
continue
|
|
try:
|
|
fk_col = fk.column
|
|
except exc.NoReferencedColumnError:
|
|
# TODO: add specific coverage here
|
|
# to test/sql/test_selectable ReduceTest
|
|
if ignore_nonexistent_tables:
|
|
continue
|
|
else:
|
|
raise
|
|
except exc.NoReferencedTableError:
|
|
# TODO: add specific coverage here
|
|
# to test/sql/test_selectable ReduceTest
|
|
if ignore_nonexistent_tables:
|
|
continue
|
|
else:
|
|
raise
|
|
if fk_col.shares_lineage(c) and \
|
|
(not only_synonyms or \
|
|
c.name == col.name):
|
|
omit.add(col)
|
|
break
|
|
|
|
if clauses:
|
|
def visit_binary(binary):
|
|
if binary.operator == operators.eq:
|
|
cols = util.column_set(chain(*[c.proxy_set
|
|
for c in columns.difference(omit)]))
|
|
if binary.left in cols and binary.right in cols:
|
|
for c in reversed(columns):
|
|
if c.shares_lineage(binary.right) and \
|
|
(not only_synonyms or \
|
|
c.name == binary.left.name):
|
|
omit.add(c)
|
|
break
|
|
for clause in clauses:
|
|
if clause is not None:
|
|
visitors.traverse(clause, {}, {'binary': visit_binary})
|
|
|
|
return expression.ColumnSet(columns.difference(omit))
|
|
|
|
|
|
def criterion_as_pairs(expression, consider_as_foreign_keys=None,
|
|
consider_as_referenced_keys=None, any_operator=False):
|
|
"""traverse an expression and locate binary criterion pairs."""
|
|
|
|
if consider_as_foreign_keys and consider_as_referenced_keys:
|
|
raise exc.ArgumentError("Can only specify one of "
|
|
"'consider_as_foreign_keys' or "
|
|
"'consider_as_referenced_keys'")
|
|
|
|
def col_is(a, b):
|
|
#return a is b
|
|
return a.compare(b)
|
|
|
|
def visit_binary(binary):
|
|
if not any_operator and binary.operator is not operators.eq:
|
|
return
|
|
if not isinstance(binary.left, sql.ColumnElement) or \
|
|
not isinstance(binary.right, sql.ColumnElement):
|
|
return
|
|
|
|
if consider_as_foreign_keys:
|
|
if binary.left in consider_as_foreign_keys and \
|
|
(col_is(binary.right, binary.left) or
|
|
binary.right not in consider_as_foreign_keys):
|
|
pairs.append((binary.right, binary.left))
|
|
elif binary.right in consider_as_foreign_keys and \
|
|
(col_is(binary.left, binary.right) or
|
|
binary.left not in consider_as_foreign_keys):
|
|
pairs.append((binary.left, binary.right))
|
|
elif consider_as_referenced_keys:
|
|
if binary.left in consider_as_referenced_keys and \
|
|
(col_is(binary.right, binary.left) or
|
|
binary.right not in consider_as_referenced_keys):
|
|
pairs.append((binary.left, binary.right))
|
|
elif binary.right in consider_as_referenced_keys and \
|
|
(col_is(binary.left, binary.right) or
|
|
binary.left not in consider_as_referenced_keys):
|
|
pairs.append((binary.right, binary.left))
|
|
else:
|
|
if isinstance(binary.left, schema.Column) and \
|
|
isinstance(binary.right, schema.Column):
|
|
if binary.left.references(binary.right):
|
|
pairs.append((binary.right, binary.left))
|
|
elif binary.right.references(binary.left):
|
|
pairs.append((binary.left, binary.right))
|
|
pairs = []
|
|
visitors.traverse(expression, {}, {'binary': visit_binary})
|
|
return pairs
|
|
|
|
|
|
class AliasedRow(object):
|
|
"""Wrap a RowProxy with a translation map.
|
|
|
|
This object allows a set of keys to be translated
|
|
to those present in a RowProxy.
|
|
|
|
"""
|
|
def __init__(self, row, map):
|
|
# AliasedRow objects don't nest, so un-nest
|
|
# if another AliasedRow was passed
|
|
if isinstance(row, AliasedRow):
|
|
self.row = row.row
|
|
else:
|
|
self.row = row
|
|
self.map = map
|
|
|
|
def __contains__(self, key):
|
|
return self.map[key] in self.row
|
|
|
|
def has_key(self, key):
|
|
return key in self
|
|
|
|
def __getitem__(self, key):
|
|
return self.row[self.map[key]]
|
|
|
|
def keys(self):
|
|
return self.row.keys()
|
|
|
|
|
|
class ClauseAdapter(visitors.ReplacingCloningVisitor):
|
|
"""Clones and modifies clauses based on column correspondence.
|
|
|
|
E.g.::
|
|
|
|
table1 = Table('sometable', metadata,
|
|
Column('col1', Integer),
|
|
Column('col2', Integer)
|
|
)
|
|
table2 = Table('someothertable', metadata,
|
|
Column('col1', Integer),
|
|
Column('col2', Integer)
|
|
)
|
|
|
|
condition = table1.c.col1 == table2.c.col1
|
|
|
|
make an alias of table1::
|
|
|
|
s = table1.alias('foo')
|
|
|
|
calling ``ClauseAdapter(s).traverse(condition)`` converts
|
|
condition to read::
|
|
|
|
s.c.col1 == table2.c.col1
|
|
|
|
"""
|
|
def __init__(self, selectable, equivalents=None,
|
|
include=None, exclude=None,
|
|
include_fn=None, exclude_fn=None,
|
|
adapt_on_names=False):
|
|
self.__traverse_options__ = {'stop_on': [selectable]}
|
|
self.selectable = selectable
|
|
if include:
|
|
assert not include_fn
|
|
self.include_fn = lambda e: e in include
|
|
else:
|
|
self.include_fn = include_fn
|
|
if exclude:
|
|
assert not exclude_fn
|
|
self.exclude_fn = lambda e: e in exclude
|
|
else:
|
|
self.exclude_fn = exclude_fn
|
|
self.equivalents = util.column_dict(equivalents or {})
|
|
self.adapt_on_names = adapt_on_names
|
|
|
|
def _corresponding_column(self, col, require_embedded,
|
|
_seen=util.EMPTY_SET):
|
|
newcol = self.selectable.corresponding_column(
|
|
col,
|
|
require_embedded=require_embedded)
|
|
if newcol is None and col in self.equivalents and col not in _seen:
|
|
for equiv in self.equivalents[col]:
|
|
newcol = self._corresponding_column(equiv,
|
|
require_embedded=require_embedded,
|
|
_seen=_seen.union([col]))
|
|
if newcol is not None:
|
|
return newcol
|
|
if self.adapt_on_names and newcol is None:
|
|
newcol = self.selectable.c.get(col.name)
|
|
return newcol
|
|
|
|
def replace(self, col):
|
|
if isinstance(col, expression.FromClause) and \
|
|
self.selectable.is_derived_from(col):
|
|
return self.selectable
|
|
elif not isinstance(col, expression.ColumnElement):
|
|
return None
|
|
elif self.include_fn and not self.include_fn(col):
|
|
return None
|
|
elif self.exclude_fn and self.exclude_fn(col):
|
|
return None
|
|
else:
|
|
return self._corresponding_column(col, True)
|
|
|
|
|
|
class ColumnAdapter(ClauseAdapter):
|
|
"""Extends ClauseAdapter with extra utility functions.
|
|
|
|
Provides the ability to "wrap" this ClauseAdapter
|
|
around another, a columns dictionary which returns
|
|
adapted elements given an original, and an
|
|
adapted_row() factory.
|
|
|
|
"""
|
|
def __init__(self, selectable, equivalents=None,
|
|
chain_to=None, include=None,
|
|
exclude=None, adapt_required=False):
|
|
ClauseAdapter.__init__(self, selectable, equivalents, include, exclude)
|
|
if chain_to:
|
|
self.chain(chain_to)
|
|
self.columns = util.populate_column_dict(self._locate_col)
|
|
self.adapt_required = adapt_required
|
|
|
|
def wrap(self, adapter):
|
|
ac = self.__class__.__new__(self.__class__)
|
|
ac.__dict__ = self.__dict__.copy()
|
|
ac._locate_col = ac._wrap(ac._locate_col, adapter._locate_col)
|
|
ac.adapt_clause = ac._wrap(ac.adapt_clause, adapter.adapt_clause)
|
|
ac.adapt_list = ac._wrap(ac.adapt_list, adapter.adapt_list)
|
|
ac.columns = util.populate_column_dict(ac._locate_col)
|
|
return ac
|
|
|
|
adapt_clause = ClauseAdapter.traverse
|
|
adapt_list = ClauseAdapter.copy_and_process
|
|
|
|
def _wrap(self, local, wrapped):
|
|
def locate(col):
|
|
col = local(col)
|
|
return wrapped(col)
|
|
return locate
|
|
|
|
def _locate_col(self, col):
|
|
c = self._corresponding_column(col, True)
|
|
if c is None:
|
|
c = self.adapt_clause(col)
|
|
|
|
# anonymize labels in case they have a hardcoded name
|
|
if isinstance(c, expression.Label):
|
|
c = c.label(None)
|
|
|
|
# adapt_required indicates that if we got the same column
|
|
# back which we put in (i.e. it passed through),
|
|
# it's not correct. this is used by eagerloading which
|
|
# knows that all columns and expressions need to be adapted
|
|
# to a result row, and a "passthrough" is definitely targeting
|
|
# the wrong column.
|
|
if self.adapt_required and c is col:
|
|
return None
|
|
|
|
return c
|
|
|
|
def adapted_row(self, row):
|
|
return AliasedRow(row, self.columns)
|
|
|
|
def __getstate__(self):
|
|
d = self.__dict__.copy()
|
|
del d['columns']
|
|
return d
|
|
|
|
def __setstate__(self, state):
|
|
self.__dict__.update(state)
|
|
self.columns = util.PopulateDict(self._locate_col)
|