# sql/util.py # Copyright (C) 2005-2023 the SQLAlchemy authors and contributors # # # This module is part of SQLAlchemy and is released under # the MIT License: https://www.opensource.org/licenses/mit-license.php # mypy: allow-untyped-defs, allow-untyped-calls """High level utilities which build upon other modules here. """ from __future__ import annotations from collections import deque import copy from itertools import chain import typing from typing import AbstractSet from typing import Any from typing import Callable from typing import cast from typing import Collection from typing import Dict from typing import Iterable from typing import Iterator from typing import List from typing import Optional from typing import overload from typing import Sequence from typing import Tuple from typing import TYPE_CHECKING from typing import TypeVar from typing import Union from . import coercions from . import operators from . import roles from . import visitors from ._typing import is_text_clause from .annotation import _deep_annotate as _deep_annotate # noqa: F401 from .annotation import _deep_deannotate as _deep_deannotate # noqa: F401 from .annotation import _shallow_annotate as _shallow_annotate # noqa: F401 from .base import _expand_cloned from .base import _from_objects from .cache_key import HasCacheKey as HasCacheKey # noqa: F401 from .ddl import sort_tables as sort_tables # noqa: F401 from .elements import _find_columns as _find_columns from .elements import _label_reference from .elements import _textual_label_reference from .elements import BindParameter from .elements import ClauseElement from .elements import ColumnClause from .elements import ColumnElement from .elements import Grouping from .elements import KeyedColumnElement from .elements import Label from .elements import NamedColumn from .elements import Null from .elements import UnaryExpression from .schema import Column from .selectable import Alias from .selectable import FromClause from .selectable import FromGrouping from .selectable import Join from .selectable import ScalarSelect from .selectable import SelectBase from .selectable import TableClause from .visitors import _ET from .. import exc from .. import util from ..util.typing import Literal from ..util.typing import Protocol if typing.TYPE_CHECKING: from ._typing import _EquivalentColumnMap from ._typing import _LimitOffsetType from ._typing import _TypeEngineArgument from .elements import BinaryExpression from .elements import TextClause from .selectable import _JoinTargetElement from .selectable import _SelectIterable from .selectable import Selectable from .visitors import _TraverseCallableType from .visitors import ExternallyTraversible from .visitors import ExternalTraversal from ..engine.interfaces import _AnyExecuteParams from ..engine.interfaces import _AnyMultiExecuteParams from ..engine.interfaces import _AnySingleExecuteParams from ..engine.interfaces import _CoreSingleExecuteParams from ..engine.row import Row _CE = TypeVar("_CE", bound="ColumnElement[Any]") def join_condition( a: FromClause, b: FromClause, a_subset: Optional[FromClause] = None, consider_as_foreign_keys: Optional[AbstractSet[ColumnClause[Any]]] = None, ) -> ColumnElement[bool]: """Create a join condition between two tables or selectables. e.g.:: join_condition(tablea, tableb) would produce an expression along the lines of:: tablea.c.id==tableb.c.tablea_id The join is determined based on the foreign key relationships between the two selectables. If there are multiple ways to join, or no way to join, an error is raised. :param a_subset: An optional expression that is a sub-component of ``a``. An attempt will be made to join to just this sub-component first before looking at the full ``a`` construct, and if found will be successful even if there are other ways to join to ``a``. This allows the "right side" of a join to be passed thereby providing a "natural join". """ return Join._join_condition( a, b, a_subset=a_subset, consider_as_foreign_keys=consider_as_foreign_keys, ) def find_join_source( clauses: List[FromClause], join_to: FromClause ) -> List[int]: """Given a list of FROM clauses and a selectable, return the first index and element from the list of clauses which can be joined against the selectable. returns None, None if no match is found. e.g.:: clause1 = table1.join(table2) clause2 = table4.join(table5) join_to = table2.join(table3) find_join_source([clause1, clause2], join_to) == clause1 """ selectables = list(_from_objects(join_to)) idx = [] for i, f in enumerate(clauses): for s in selectables: if f.is_derived_from(s): idx.append(i) return idx def find_left_clause_that_matches_given( clauses: Sequence[FromClause], join_from: FromClause ) -> List[int]: """Given a list of FROM clauses and a selectable, return the indexes from the list of clauses which is derived from the selectable. """ selectables = list(_from_objects(join_from)) liberal_idx = [] for i, f in enumerate(clauses): for s in selectables: # basic check, if f is derived from s. # this can be joins containing a table, or an aliased table # or select statement matching to a table. This check # will match a table to a selectable that is adapted from # that table. With Query, this suits the case where a join # is being made to an adapted entity if f.is_derived_from(s): liberal_idx.append(i) break # in an extremely small set of use cases, a join is being made where # there are multiple FROM clauses where our target table is represented # in more than one, such as embedded or similar. in this case, do # another pass where we try to get a more exact match where we aren't # looking at adaption relationships. if len(liberal_idx) > 1: conservative_idx = [] for idx in liberal_idx: f = clauses[idx] for s in selectables: if set(surface_selectables(f)).intersection( surface_selectables(s) ): conservative_idx.append(idx) break if conservative_idx: return conservative_idx return liberal_idx def find_left_clause_to_join_from( clauses: Sequence[FromClause], join_to: _JoinTargetElement, onclause: Optional[ColumnElement[Any]], ) -> List[int]: """Given a list of FROM clauses, a selectable, and optional ON clause, return a list of integer indexes from the clauses list indicating the clauses that can be joined from. The presence of an "onclause" indicates that at least one clause can definitely be joined from; if the list of clauses is of length one and the onclause is given, returns that index. If the list of clauses is more than length one, and the onclause is given, attempts to locate which clauses contain the same columns. """ idx = [] selectables = set(_from_objects(join_to)) # if we are given more than one target clause to join # from, use the onclause to provide a more specific answer. # otherwise, don't try to limit, after all, "ON TRUE" is a valid # on clause if len(clauses) > 1 and onclause is not None: resolve_ambiguity = True cols_in_onclause = _find_columns(onclause) else: resolve_ambiguity = False cols_in_onclause = None for i, f in enumerate(clauses): for s in selectables.difference([f]): if resolve_ambiguity: assert cols_in_onclause is not None if set(f.c).union(s.c).issuperset(cols_in_onclause): idx.append(i) break elif onclause is not None or Join._can_join(f, s): idx.append(i) break if len(idx) > 1: # this is the same "hide froms" logic from # Selectable._get_display_froms toremove = set( chain(*[_expand_cloned(f._hide_froms) for f in clauses]) ) idx = [i for i in idx if clauses[i] not in toremove] # onclause was given and none of them resolved, so assume # all indexes can match if not idx and onclause is not None: return list(range(len(clauses))) else: return idx def visit_binary_product( fn: Callable[ [BinaryExpression[Any], ColumnElement[Any], ColumnElement[Any]], None ], expr: ColumnElement[Any], ) -> None: """Produce a traversal of the given expression, delivering column comparisons to the given function. The function is of the form:: def my_fn(binary, left, right) For each binary expression located which has a comparison operator, the product of "left" and "right" will be delivered to that function, in terms of that binary. Hence an expression like:: and_( (a + b) == q + func.sum(e + f), j == r ) would have the traversal:: a q a e a f b q b e b f j r That is, every combination of "left" and "right" that doesn't further contain a binary comparison is passed as pairs. """ stack: List[BinaryExpression[Any]] = [] def visit(element: ClauseElement) -> Iterator[ColumnElement[Any]]: if isinstance(element, ScalarSelect): # we don't want to dig into correlated subqueries, # those are just column elements by themselves yield element elif element.__visit_name__ == "binary" and operators.is_comparison( element.operator # type: ignore ): stack.insert(0, element) # type: ignore for l in visit(element.left): # type: ignore for r in visit(element.right): # type: ignore fn(stack[0], l, r) stack.pop(0) for elem in element.get_children(): visit(elem) else: if isinstance(element, ColumnClause): yield element for elem in element.get_children(): yield from visit(elem) list(visit(expr)) visit = None # type: ignore # remove gc cycles def find_tables( clause: ClauseElement, *, check_columns: bool = False, include_aliases: bool = False, include_joins: bool = False, include_selects: bool = False, include_crud: bool = False, ) -> List[TableClause]: """locate Table objects within the given expression.""" tables: List[TableClause] = [] _visitors: Dict[str, _TraverseCallableType[Any]] = {} if include_selects: _visitors["select"] = _visitors["compound_select"] = tables.append if include_joins: _visitors["join"] = tables.append if include_aliases: _visitors["alias"] = _visitors["subquery"] = _visitors[ "tablesample" ] = _visitors["lateral"] = tables.append if include_crud: _visitors["insert"] = _visitors["update"] = _visitors[ "delete" ] = lambda ent: tables.append(ent.table) if check_columns: def visit_column(column): tables.append(column.table) _visitors["column"] = visit_column _visitors["table"] = tables.append visitors.traverse(clause, {}, _visitors) return tables def unwrap_order_by(clause): """Break up an 'order by' expression into individual column-expressions, without DESC/ASC/NULLS FIRST/NULLS LAST""" cols = util.column_set() result = [] stack = deque([clause]) # examples # column -> ASC/DESC == column # column -> ASC/DESC -> label == column # column -> label -> ASC/DESC -> label == column # scalar_select -> label -> ASC/DESC == scalar_select -> label while stack: t = stack.popleft() if isinstance(t, ColumnElement) and ( not isinstance(t, UnaryExpression) or not operators.is_ordering_modifier(t.modifier) # type: ignore ): if isinstance(t, Label) and not isinstance( t.element, ScalarSelect ): t = t.element if isinstance(t, Grouping): t = t.element stack.append(t) continue elif isinstance(t, _label_reference): t = t.element stack.append(t) continue if isinstance(t, (_textual_label_reference)): continue if t not in cols: cols.add(t) result.append(t) else: for c in t.get_children(): stack.append(c) return result def unwrap_label_reference(element): def replace( element: ExternallyTraversible, **kw: Any ) -> Optional[ExternallyTraversible]: if isinstance(element, _label_reference): return element.element elif isinstance(element, _textual_label_reference): assert False, "can't unwrap a textual label reference" return None return visitors.replacement_traverse(element, {}, replace) def expand_column_list_from_order_by(collist, order_by): """Given the columns clause and ORDER BY of a selectable, return a list of column expressions that can be added to the collist corresponding to the ORDER BY, without repeating those already in the collist. """ cols_already_present = { col.element if col._order_by_label_element is not None else col for col in collist } to_look_for = list(chain(*[unwrap_order_by(o) for o in order_by])) return [col for col in to_look_for if col not in cols_already_present] def clause_is_present(clause, search): """Given a target clause and a second to search within, return True if the target is plainly present in the search without any subqueries or aliases involved. Basically descends through Joins. """ for elem in surface_selectables(search): if clause == elem: # use == here so that Annotated's compare return True else: return False def tables_from_leftmost(clause: FromClause) -> Iterator[FromClause]: if isinstance(clause, Join): yield from tables_from_leftmost(clause.left) yield from tables_from_leftmost(clause.right) elif isinstance(clause, FromGrouping): yield from tables_from_leftmost(clause.element) else: yield clause def surface_selectables(clause): stack = [clause] while stack: elem = stack.pop() yield elem if isinstance(elem, Join): stack.extend((elem.left, elem.right)) elif isinstance(elem, FromGrouping): stack.append(elem.element) def surface_selectables_only(clause): stack = [clause] while stack: elem = stack.pop() if isinstance(elem, (TableClause, Alias)): yield elem if isinstance(elem, Join): stack.extend((elem.left, elem.right)) elif isinstance(elem, FromGrouping): stack.append(elem.element) elif isinstance(elem, ColumnClause): if elem.table is not None: stack.append(elem.table) else: yield elem elif elem is not None: yield elem def extract_first_column_annotation(column, annotation_name): filter_ = (FromGrouping, SelectBase) stack = deque([column]) while stack: elem = stack.popleft() if annotation_name in elem._annotations: return elem._annotations[annotation_name] for sub in elem.get_children(): if isinstance(sub, filter_): continue stack.append(sub) return None def selectables_overlap(left: FromClause, right: FromClause) -> bool: """Return True if left/right have some overlapping selectable""" return bool( set(surface_selectables(left)).intersection(surface_selectables(right)) ) def bind_values(clause): """Return an ordered list of "bound" values in the given clause. E.g.:: >>> expr = and_( ... table.c.foo==5, table.c.foo==7 ... ) >>> bind_values(expr) [5, 7] """ v = [] def visit_bindparam(bind): v.append(bind.effective_value) visitors.traverse(clause, {}, {"bindparam": visit_bindparam}) return v def _quote_ddl_expr(element): if isinstance(element, str): element = element.replace("'", "''") return "'%s'" % element else: return repr(element) class _repr_base: _LIST: int = 0 _TUPLE: int = 1 _DICT: int = 2 __slots__ = ("max_chars",) max_chars: int def trunc(self, value: Any) -> str: rep = repr(value) lenrep = len(rep) if lenrep > self.max_chars: segment_length = self.max_chars // 2 rep = ( rep[0:segment_length] + ( " ... (%d characters truncated) ... " % (lenrep - self.max_chars) ) + rep[-segment_length:] ) return rep def _repr_single_value(value): rp = _repr_base() rp.max_chars = 300 return rp.trunc(value) class _repr_row(_repr_base): """Provide a string view of a row.""" __slots__ = ("row",) def __init__(self, row: Row[Any], max_chars: int = 300): self.row = row self.max_chars = max_chars def __repr__(self) -> str: trunc = self.trunc return "(%s%s)" % ( ", ".join(trunc(value) for value in self.row), "," if len(self.row) == 1 else "", ) class _long_statement(str): def __str__(self) -> str: lself = len(self) if lself > 500: lleft = 250 lright = 100 trunc = lself - lleft - lright return ( f"{self[0:lleft]} ... {trunc} " f"characters truncated ... {self[-lright:]}" ) else: return str.__str__(self) class _repr_params(_repr_base): """Provide a string view of bound parameters. Truncates display to a given number of 'multi' parameter sets, as well as long values to a given number of characters. """ __slots__ = "params", "batches", "ismulti", "max_params" def __init__( self, params: Optional[_AnyExecuteParams], batches: int, max_params: int = 100, max_chars: int = 300, ismulti: Optional[bool] = None, ): self.params = params self.ismulti = ismulti self.batches = batches self.max_chars = max_chars self.max_params = max_params def __repr__(self) -> str: if self.ismulti is None: return self.trunc(self.params) if isinstance(self.params, list): typ = self._LIST elif isinstance(self.params, tuple): typ = self._TUPLE elif isinstance(self.params, dict): typ = self._DICT else: return self.trunc(self.params) if self.ismulti: multi_params = cast( "_AnyMultiExecuteParams", self.params, ) if len(self.params) > self.batches: msg = ( " ... displaying %i of %i total bound parameter sets ... " ) return " ".join( ( self._repr_multi( multi_params[: self.batches - 2], typ, )[0:-1], msg % (self.batches, len(self.params)), self._repr_multi(multi_params[-2:], typ)[1:], ) ) else: return self._repr_multi(multi_params, typ) else: return self._repr_params( cast( "_AnySingleExecuteParams", self.params, ), typ, ) def _repr_multi( self, multi_params: _AnyMultiExecuteParams, typ: int, ) -> str: if multi_params: if isinstance(multi_params[0], list): elem_type = self._LIST elif isinstance(multi_params[0], tuple): elem_type = self._TUPLE elif isinstance(multi_params[0], dict): elem_type = self._DICT else: assert False, "Unknown parameter type %s" % ( type(multi_params[0]) ) elements = ", ".join( self._repr_params(params, elem_type) for params in multi_params ) else: elements = "" if typ == self._LIST: return "[%s]" % elements else: return "(%s)" % elements def _get_batches(self, params: Iterable[Any]) -> Any: lparams = list(params) lenparams = len(lparams) if lenparams > self.max_params: lleft = self.max_params // 2 return ( lparams[0:lleft], lparams[-lleft:], lenparams - self.max_params, ) else: return lparams, None, None def _repr_params( self, params: _AnySingleExecuteParams, typ: int, ) -> str: if typ is self._DICT: return self._repr_param_dict( cast("_CoreSingleExecuteParams", params) ) elif typ is self._TUPLE: return self._repr_param_tuple(cast("Sequence[Any]", params)) else: return self._repr_param_list(params) def _repr_param_dict(self, params: _CoreSingleExecuteParams) -> str: trunc = self.trunc ( items_first_batch, items_second_batch, trunclen, ) = self._get_batches(params.items()) if items_second_batch: text = "{%s" % ( ", ".join( f"{key!r}: {trunc(value)}" for key, value in items_first_batch ) ) text += f" ... {trunclen} parameters truncated ... " text += "%s}" % ( ", ".join( f"{key!r}: {trunc(value)}" for key, value in items_second_batch ) ) else: text = "{%s}" % ( ", ".join( f"{key!r}: {trunc(value)}" for key, value in items_first_batch ) ) return text def _repr_param_tuple(self, params: Sequence[Any]) -> str: trunc = self.trunc ( items_first_batch, items_second_batch, trunclen, ) = self._get_batches(params) if items_second_batch: text = "(%s" % ( ", ".join(trunc(value) for value in items_first_batch) ) text += f" ... {trunclen} parameters truncated ... " text += "%s)" % ( ", ".join(trunc(value) for value in items_second_batch), ) else: text = "(%s%s)" % ( ", ".join(trunc(value) for value in items_first_batch), "," if len(items_first_batch) == 1 else "", ) return text def _repr_param_list(self, params: _AnySingleExecuteParams) -> str: trunc = self.trunc ( items_first_batch, items_second_batch, trunclen, ) = self._get_batches(params) if items_second_batch: text = "[%s" % ( ", ".join(trunc(value) for value in items_first_batch) ) text += f" ... {trunclen} parameters truncated ... " text += "%s]" % ( ", ".join(trunc(value) for value in items_second_batch) ) else: text = "[%s]" % ( ", ".join(trunc(value) for value in items_first_batch) ) return text def adapt_criterion_to_null(crit: _CE, nulls: Collection[Any]) -> _CE: """given criterion containing bind params, convert selected elements to IS NULL. """ def visit_binary(binary): if ( isinstance(binary.left, BindParameter) and binary.left._identifying_key in nulls ): # reverse order if the NULL is on the left side binary.left = binary.right binary.right = Null() binary.operator = operators.is_ binary.negate = operators.is_not elif ( isinstance(binary.right, BindParameter) and binary.right._identifying_key in nulls ): binary.right = Null() binary.operator = operators.is_ binary.negate = operators.is_not return visitors.cloned_traverse(crit, {}, {"binary": visit_binary}) def splice_joins( left: Optional[FromClause], right: Optional[FromClause], stop_on: Optional[FromClause] = None, ) -> Optional[FromClause]: if left is None: return right stack: List[Tuple[Optional[FromClause], Optional[Join]]] = [(right, None)] adapter = ClauseAdapter(left) ret = None while stack: (right, prevright) = stack.pop() if isinstance(right, Join) and right is not stop_on: right = right._clone() right.onclause = adapter.traverse(right.onclause) stack.append((right.left, right)) else: right = adapter.traverse(right) if prevright is not None: assert right is not None prevright.left = right if ret is None: ret = right return ret @overload def reduce_columns( columns: Iterable[ColumnElement[Any]], *clauses: Optional[ClauseElement], **kw: bool, ) -> Sequence[ColumnElement[Any]]: ... @overload def reduce_columns( columns: _SelectIterable, *clauses: Optional[ClauseElement], **kw: bool, ) -> Sequence[Union[ColumnElement[Any], TextClause]]: ... def reduce_columns( columns: _SelectIterable, *clauses: Optional[ClauseElement], **kw: bool, ) -> Collection[Union[ColumnElement[Any], TextClause]]: r"""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 selectable to just those that are not repeated. """ ignore_nonexistent_tables = kw.pop("ignore_nonexistent_tables", False) only_synonyms = kw.pop("only_synonyms", False) column_set = util.OrderedSet(columns) cset_no_text: util.OrderedSet[ColumnElement[Any]] = column_set.difference( c for c in column_set if is_text_clause(c) # type: ignore ) omit = util.column_set() for col in cset_no_text: for fk in chain(*[c.foreign_keys for c in col.proxy_set]): for c in cset_no_text: 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 cset_no_text.difference(omit)] ) ) if binary.left in cols and binary.right in cols: for c in reversed(cset_no_text): 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 column_set.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, ColumnElement) or not isinstance( binary.right, 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, Column) and isinstance( binary.right, 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: List[Tuple[ColumnElement[Any], ColumnElement[Any]]] = [] visitors.traverse(expression, {}, {"binary": visit_binary}) return pairs class ClauseAdapter(visitors.ReplacingExternalTraversal): """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 """ __slots__ = ( "__traverse_options__", "selectable", "include_fn", "exclude_fn", "equivalents", "adapt_on_names", "adapt_from_selectables", ) def __init__( self, selectable: Selectable, equivalents: Optional[_EquivalentColumnMap] = None, include_fn: Optional[Callable[[ClauseElement], bool]] = None, exclude_fn: Optional[Callable[[ClauseElement], bool]] = None, adapt_on_names: bool = False, anonymize_labels: bool = False, adapt_from_selectables: Optional[AbstractSet[FromClause]] = None, ): self.__traverse_options__ = { "stop_on": [selectable], "anonymize_labels": anonymize_labels, } self.selectable = selectable self.include_fn = include_fn self.exclude_fn = exclude_fn self.equivalents = util.column_dict(equivalents or {}) self.adapt_on_names = adapt_on_names self.adapt_from_selectables = adapt_from_selectables if TYPE_CHECKING: @overload def traverse(self, obj: Literal[None]) -> None: ... # note this specializes the ReplacingExternalTraversal.traverse() # method to state # that we will return the same kind of ExternalTraversal object as # we were given. This is probably not 100% true, such as it's # possible for us to swap out Alias for Table at the top level. # Ideally there could be overloads specific to ColumnElement and # FromClause but Mypy is not accepting those as compatible with # the base ReplacingExternalTraversal @overload def traverse(self, obj: _ET) -> _ET: ... def traverse( self, obj: Optional[ExternallyTraversible] ) -> Optional[ExternallyTraversible]: ... 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 and isinstance(col, NamedColumn) ): newcol = self.selectable.exported_columns.get(col.name) return newcol @util.preload_module("sqlalchemy.sql.functions") def replace( self, col: _ET, _include_singleton_constants: bool = False ) -> Optional[_ET]: functions = util.preloaded.sql_functions # TODO: cython candidate if self.include_fn and not self.include_fn(col): # type: ignore return None elif self.exclude_fn and self.exclude_fn(col): # type: ignore return None if isinstance(col, FromClause) and not isinstance( col, functions.FunctionElement ): if self.selectable.is_derived_from(col): if self.adapt_from_selectables: for adp in self.adapt_from_selectables: if adp.is_derived_from(col): break else: return None return self.selectable # type: ignore elif isinstance(col, Alias) and isinstance( col.element, TableClause ): # we are a SELECT statement and not derived from an alias of a # table (which nonetheless may be a table our SELECT derives # from), so return the alias to prevent further traversal # or # we are an alias of a table and we are not derived from an # alias of a table (which nonetheless may be the same table # as ours) so, same thing return col # type: ignore else: # other cases where we are a selectable and the element # is another join or selectable that contains a table which our # selectable derives from, that we want to process return None elif not isinstance(col, ColumnElement): return None elif not _include_singleton_constants and col._is_singleton_constant: # dont swap out NULL, TRUE, FALSE for a label name # in a SQL statement that's being rewritten, # leave them as the constant. This is first noted in #6259, # however the logic to check this moved here as of #7154 so that # it is made specific to SQL rewriting and not all column # correspondence return None if "adapt_column" in col._annotations: col = col._annotations["adapt_column"] if TYPE_CHECKING: assert isinstance(col, KeyedColumnElement) if self.adapt_from_selectables and col not in self.equivalents: for adp in self.adapt_from_selectables: if adp.c.corresponding_column(col, False) is not None: break else: return None if TYPE_CHECKING: assert isinstance(col, KeyedColumnElement) return self._corresponding_column( # type: ignore col, require_embedded=True ) class _ColumnLookup(Protocol): @overload def __getitem__(self, key: None) -> None: ... @overload def __getitem__(self, key: ColumnClause[Any]) -> ColumnClause[Any]: ... @overload def __getitem__(self, key: ColumnElement[Any]) -> ColumnElement[Any]: ... @overload def __getitem__(self, key: _ET) -> _ET: ... def __getitem__(self, key: Any) -> Any: ... class ColumnAdapter(ClauseAdapter): """Extends ClauseAdapter with extra utility functions. Key aspects of ColumnAdapter include: * Expressions that are adapted are stored in a persistent .columns collection; so that an expression E adapted into an expression E1, will return the same object E1 when adapted a second time. This is important in particular for things like Label objects that are anonymized, so that the ColumnAdapter can be used to present a consistent "adapted" view of things. * Exclusion of items from the persistent collection based on include/exclude rules, but also independent of hash identity. This because "annotated" items all have the same hash identity as their parent. * "wrapping" capability is added, so that the replacement of an expression E can proceed through a series of adapters. This differs from the visitor's "chaining" feature in that the resulting object is passed through all replacing functions unconditionally, rather than stopping at the first one that returns non-None. * An adapt_required option, used by eager loading to indicate that We don't trust a result row column that is not translated. This is to prevent a column from being interpreted as that of the child row in a self-referential scenario, see inheritance/test_basic.py->EagerTargetingTest.test_adapt_stringency """ __slots__ = ( "columns", "adapt_required", "allow_label_resolve", "_wrap", "__weakref__", ) columns: _ColumnLookup def __init__( self, selectable: Selectable, equivalents: Optional[_EquivalentColumnMap] = None, adapt_required: bool = False, include_fn: Optional[Callable[[ClauseElement], bool]] = None, exclude_fn: Optional[Callable[[ClauseElement], bool]] = None, adapt_on_names: bool = False, allow_label_resolve: bool = True, anonymize_labels: bool = False, adapt_from_selectables: Optional[AbstractSet[FromClause]] = None, ): super().__init__( selectable, equivalents, include_fn=include_fn, exclude_fn=exclude_fn, adapt_on_names=adapt_on_names, anonymize_labels=anonymize_labels, adapt_from_selectables=adapt_from_selectables, ) self.columns = util.WeakPopulateDict(self._locate_col) # type: ignore if self.include_fn or self.exclude_fn: self.columns = self._IncludeExcludeMapping(self, self.columns) self.adapt_required = adapt_required self.allow_label_resolve = allow_label_resolve self._wrap = None class _IncludeExcludeMapping: def __init__(self, parent, columns): self.parent = parent self.columns = columns def __getitem__(self, key): if ( self.parent.include_fn and not self.parent.include_fn(key) ) or (self.parent.exclude_fn and self.parent.exclude_fn(key)): if self.parent._wrap: return self.parent._wrap.columns[key] else: return key return self.columns[key] def wrap(self, adapter): ac = copy.copy(self) ac._wrap = adapter ac.columns = util.WeakPopulateDict(ac._locate_col) # type: ignore if ac.include_fn or ac.exclude_fn: ac.columns = self._IncludeExcludeMapping(ac, ac.columns) return ac @overload def traverse(self, obj: Literal[None]) -> None: ... @overload def traverse(self, obj: _ET) -> _ET: ... def traverse( self, obj: Optional[ExternallyTraversible] ) -> Optional[ExternallyTraversible]: return self.columns[obj] def chain(self, visitor: ExternalTraversal) -> ColumnAdapter: assert isinstance(visitor, ColumnAdapter) return super().chain(visitor) if TYPE_CHECKING: @property def visitor_iterator(self) -> Iterator[ColumnAdapter]: ... adapt_clause = traverse adapt_list = ClauseAdapter.copy_and_process def adapt_check_present( self, col: ColumnElement[Any] ) -> Optional[ColumnElement[Any]]: newcol = self.columns[col] if newcol is col and self._corresponding_column(col, True) is None: return None return newcol def _locate_col( self, col: ColumnElement[Any] ) -> Optional[ColumnElement[Any]]: # both replace and traverse() are overly complicated for what # we are doing here and we would do better to have an inlined # version that doesn't build up as much overhead. the issue is that # sometimes the lookup does in fact have to adapt the insides of # say a labeled scalar subquery. However, if the object is an # Immutable, i.e. Column objects, we can skip the "clone" / # "copy internals" part since those will be no-ops in any case. # additionally we want to catch singleton objects null/true/false # and make sure they are adapted as well here. if col._is_immutable: for vis in self.visitor_iterator: c = vis.replace(col, _include_singleton_constants=True) if c is not None: break else: c = col else: c = ClauseAdapter.traverse(self, col) if self._wrap: c2 = self._wrap._locate_col(c) if c2 is not None: c = c2 if self.adapt_required and c is col: return None # allow_label_resolve is consumed by one case for joined eager loading # as part of its logic to prevent its own columns from being affected # by .order_by(). Before full typing were applied to the ORM, this # logic would set this attribute on the incoming object (which is # typically a column, but we have a test for it being a non-column # object) if no column were found. While this seemed to # have no negative effects, this adjustment should only occur on the # new column which is assumed to be local to an adapted selectable. if c is not col: c._allow_label_resolve = self.allow_label_resolve return c def _offset_or_limit_clause( element: _LimitOffsetType, name: Optional[str] = None, type_: Optional[_TypeEngineArgument[int]] = None, ) -> ColumnElement[int]: """Convert the given value to an "offset or limit" clause. This handles incoming integers and converts to an expression; if an expression is already given, it is passed through. """ return coercions.expect( roles.LimitOffsetRole, element, name=name, type_=type_ ) def _offset_or_limit_clause_asint_if_possible( clause: _LimitOffsetType, ) -> _LimitOffsetType: """Return the offset or limit clause as a simple integer if possible, else return the clause. """ if clause is None: return None if hasattr(clause, "_limit_offset_value"): value = clause._limit_offset_value # type: ignore return util.asint(value) else: return clause def _make_slice( limit_clause: _LimitOffsetType, offset_clause: _LimitOffsetType, start: int, stop: int, ) -> Tuple[Optional[ColumnElement[int]], Optional[ColumnElement[int]]]: """Compute LIMIT/OFFSET in terms of slice start/end""" # for calculated limit/offset, try to do the addition of # values to offset in Python, however if a SQL clause is present # then the addition has to be on the SQL side. # TODO: typing is finding a few gaps in here, see if they can be # closed up if start is not None and stop is not None: offset_clause = _offset_or_limit_clause_asint_if_possible( offset_clause ) if offset_clause is None: offset_clause = 0 if start != 0: offset_clause = offset_clause + start # type: ignore if offset_clause == 0: offset_clause = None else: assert offset_clause is not None offset_clause = _offset_or_limit_clause(offset_clause) limit_clause = _offset_or_limit_clause(stop - start) elif start is None and stop is not None: limit_clause = _offset_or_limit_clause(stop) elif start is not None and stop is None: offset_clause = _offset_or_limit_clause_asint_if_possible( offset_clause ) if offset_clause is None: offset_clause = 0 if start != 0: offset_clause = offset_clause + start # type: ignore if offset_clause == 0: offset_clause = None else: offset_clause = _offset_or_limit_clause( offset_clause # type: ignore ) return limit_clause, offset_clause # type: ignore