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- # sql/roles.py
- # Copyright (C) 2005-2021 the SQLAlchemy authors and contributors
- # <see AUTHORS file>
- #
- # This module is part of SQLAlchemy and is released under
- # the MIT License: http://www.opensource.org/licenses/mit-license.php
-
- from .. import util
-
-
- class SQLRole(object):
- """Define a "role" within a SQL statement structure.
-
- Classes within SQL Core participate within SQLRole hierarchies in order
- to more accurately indicate where they may be used within SQL statements
- of all types.
-
- .. versionadded:: 1.4
-
- """
-
- allows_lambda = False
- uses_inspection = False
-
-
- class UsesInspection(object):
- _post_inspect = None
- uses_inspection = True
-
-
- class AllowsLambdaRole(object):
- allows_lambda = True
-
-
- class HasCacheKeyRole(SQLRole):
- _role_name = "Cacheable Core or ORM object"
-
-
- class LiteralValueRole(SQLRole):
- _role_name = "Literal Python value"
-
-
- class ColumnArgumentRole(SQLRole):
- _role_name = "Column expression"
-
-
- class ColumnArgumentOrKeyRole(ColumnArgumentRole):
- _role_name = "Column expression or string key"
-
-
- class StrAsPlainColumnRole(ColumnArgumentRole):
- _role_name = "Column expression or string key"
-
-
- class ColumnListRole(SQLRole):
- """Elements suitable for forming comma separated lists of expressions."""
-
-
- class TruncatedLabelRole(SQLRole):
- _role_name = "String SQL identifier"
-
-
- class ColumnsClauseRole(AllowsLambdaRole, UsesInspection, ColumnListRole):
- _role_name = "Column expression or FROM clause"
-
- @property
- def _select_iterable(self):
- raise NotImplementedError()
-
-
- class LimitOffsetRole(SQLRole):
- _role_name = "LIMIT / OFFSET expression"
-
-
- class ByOfRole(ColumnListRole):
- _role_name = "GROUP BY / OF / etc. expression"
-
-
- class GroupByRole(AllowsLambdaRole, UsesInspection, ByOfRole):
- # note there's a special case right now where you can pass a whole
- # ORM entity to group_by() and it splits out. we may not want to keep
- # this around
-
- _role_name = "GROUP BY expression"
-
-
- class OrderByRole(AllowsLambdaRole, ByOfRole):
- _role_name = "ORDER BY expression"
-
-
- class StructuralRole(SQLRole):
- pass
-
-
- class StatementOptionRole(StructuralRole):
- _role_name = "statement sub-expression element"
-
-
- class OnClauseRole(AllowsLambdaRole, StructuralRole):
- _role_name = "SQL expression for ON clause"
-
-
- class WhereHavingRole(OnClauseRole):
- _role_name = "SQL expression for WHERE/HAVING role"
-
-
- class ExpressionElementRole(SQLRole):
- _role_name = "SQL expression element"
-
-
- class ConstExprRole(ExpressionElementRole):
- _role_name = "Constant True/False/None expression"
-
-
- class LabeledColumnExprRole(ExpressionElementRole):
- pass
-
-
- class BinaryElementRole(ExpressionElementRole):
- _role_name = "SQL expression element or literal value"
-
-
- class InElementRole(SQLRole):
- _role_name = (
- "IN expression list, SELECT construct, or bound parameter object"
- )
-
-
- class JoinTargetRole(AllowsLambdaRole, UsesInspection, StructuralRole):
- _role_name = (
- "Join target, typically a FROM expression, or ORM "
- "relationship attribute"
- )
-
-
- class FromClauseRole(ColumnsClauseRole, JoinTargetRole):
- _role_name = "FROM expression, such as a Table or alias() object"
-
- _is_subquery = False
-
- @property
- def _hide_froms(self):
- raise NotImplementedError()
-
-
- class StrictFromClauseRole(FromClauseRole):
- # does not allow text() or select() objects
- pass
-
-
- class AnonymizedFromClauseRole(StrictFromClauseRole):
- # calls .alias() as a post processor
-
- def _anonymous_fromclause(self, name=None, flat=False):
- raise NotImplementedError()
-
-
- class ReturnsRowsRole(SQLRole):
- _role_name = (
- "Row returning expression such as a SELECT, a FROM clause, or an "
- "INSERT/UPDATE/DELETE with RETURNING"
- )
-
-
- class StatementRole(SQLRole):
- _role_name = "Executable SQL or text() construct"
-
- _propagate_attrs = util.immutabledict()
-
-
- class SelectStatementRole(StatementRole, ReturnsRowsRole):
- _role_name = "SELECT construct or equivalent text() construct"
-
- def subquery(self):
- raise NotImplementedError(
- "All SelectStatementRole objects should implement a "
- ".subquery() method."
- )
-
-
- class HasCTERole(ReturnsRowsRole):
- pass
-
-
- class CompoundElementRole(AllowsLambdaRole, SQLRole):
- """SELECT statements inside a CompoundSelect, e.g. UNION, EXTRACT, etc."""
-
- _role_name = (
- "SELECT construct for inclusion in a UNION or other set construct"
- )
-
-
- # TODO: are we using this?
- class DMLRole(StatementRole):
- pass
-
-
- class DMLTableRole(FromClauseRole):
- _role_name = "subject table for an INSERT, UPDATE or DELETE"
-
-
- class DMLColumnRole(SQLRole):
- _role_name = "SET/VALUES column expression or string key"
-
-
- class DMLSelectRole(SQLRole):
- """A SELECT statement embedded in DML, typically INSERT from SELECT"""
-
- _role_name = "SELECT statement or equivalent textual object"
-
-
- class DDLRole(StatementRole):
- pass
-
-
- class DDLExpressionRole(StructuralRole):
- _role_name = "SQL expression element for DDL constraint"
-
-
- class DDLConstraintColumnRole(SQLRole):
- _role_name = "String column name or column expression for DDL constraint"
-
-
- class DDLReferredColumnRole(DDLConstraintColumnRole):
- _role_name = (
- "String column name or Column object for DDL foreign key constraint"
- )
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