# ext/mypy/plugin.py
# Copyright (C) 2021-2025 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: https://www.opensource.org/licenses/mit-license.php
"""
Mypy plugin for SQLAlchemy ORM.
"""
from __future__ import annotations
from typing import Callable
from typing import List
from typing import Optional
from typing import Tuple
from typing import Type as TypingType
from typing import Union
from mypy import nodes
from mypy.mro import calculate_mro
from mypy.mro import MroError
from mypy.nodes import Block
from mypy.nodes import ClassDef
from mypy.nodes import GDEF
from mypy.nodes import MypyFile
from mypy.nodes import NameExpr
from mypy.nodes import SymbolTable
from mypy.nodes import SymbolTableNode
from mypy.nodes import TypeInfo
from mypy.plugin import AttributeContext
from mypy.plugin import ClassDefContext
from mypy.plugin import DynamicClassDefContext
from mypy.plugin import Plugin
from mypy.plugin import SemanticAnalyzerPluginInterface
from mypy.types import get_proper_type
from mypy.types import Instance
from mypy.types import Type
from . import decl_class
from . import names
from . import util
try:
__import__("sqlalchemy-stubs")
except ImportError:
pass
else:
raise ImportError(
"The SQLAlchemy mypy plugin in SQLAlchemy "
"2.0 does not work with sqlalchemy-stubs or "
"sqlalchemy2-stubs installed, as well as with any other third party "
"SQLAlchemy stubs. Please uninstall all SQLAlchemy stubs "
"packages."
)
class SQLAlchemyPlugin(Plugin):
def get_dynamic_class_hook(
self, fullname: str
) -> Optional[Callable[[DynamicClassDefContext], None]]:
if names.type_id_for_fullname(fullname) is names.DECLARATIVE_BASE:
return _dynamic_class_hook
return None
def get_customize_class_mro_hook(
self, fullname: str
) -> Optional[Callable[[ClassDefContext], None]]:
return _fill_in_decorators
def get_class_decorator_hook(
self, fullname: str
) -> Optional[Callable[[ClassDefContext], None]]:
sym = self.lookup_fully_qualified(fullname)
if sym is not None and sym.node is not None:
type_id = names.type_id_for_named_node(sym.node)
if type_id is names.MAPPED_DECORATOR:
return _cls_decorator_hook
elif type_id in (
names.AS_DECLARATIVE,
names.AS_DECLARATIVE_BASE,
):
return _base_cls_decorator_hook
elif type_id is names.DECLARATIVE_MIXIN:
return _declarative_mixin_hook
return None
def get_metaclass_hook(
self, fullname: str
) -> Optional[Callable[[ClassDefContext], None]]:
if names.type_id_for_fullname(fullname) is names.DECLARATIVE_META:
# Set any classes that explicitly have metaclass=DeclarativeMeta
# as declarative so the check in `get_base_class_hook()` works
return _metaclass_cls_hook
return None
def get_base_class_hook(
self, fullname: str
) -> Optional[Callable[[ClassDefContext], None]]:
sym = self.lookup_fully_qualified(fullname)
if (
sym
and isinstance(sym.node, TypeInfo)
and util.has_declarative_base(sym.node)
):
return _base_cls_hook
return None
def get_attribute_hook(
self, fullname: str
) -> Optional[Callable[[AttributeContext], Type]]:
if fullname.startswith(
"sqlalchemy.orm.attributes.QueryableAttribute."
):
return _queryable_getattr_hook
return None
def get_additional_deps(
self, file: MypyFile
) -> List[Tuple[int, str, int]]:
return [
#
(10, "sqlalchemy.orm", -1),
(10, "sqlalchemy.orm.attributes", -1),
(10, "sqlalchemy.orm.decl_api", -1),
]
def plugin(version: str) -> TypingType[SQLAlchemyPlugin]:
return SQLAlchemyPlugin
def _dynamic_class_hook(ctx: DynamicClassDefContext) -> None:
"""Generate a declarative Base class when the declarative_base() function
is encountered."""
_add_globals(ctx)
cls = ClassDef(ctx.name, Block([]))
cls.fullname = ctx.api.qualified_name(ctx.name)
info = TypeInfo(SymbolTable(), cls, ctx.api.cur_mod_id)
cls.info = info
_set_declarative_metaclass(ctx.api, cls)
cls_arg = util.get_callexpr_kwarg(ctx.call, "cls", expr_types=(NameExpr,))
if cls_arg is not None and isinstance(cls_arg.node, TypeInfo):
util.set_is_base(cls_arg.node)
decl_class.scan_declarative_assignments_and_apply_types(
cls_arg.node.defn, ctx.api, is_mixin_scan=True
)
info.bases = [Instance(cls_arg.node, [])]
else:
obj = ctx.api.named_type(names.NAMED_TYPE_BUILTINS_OBJECT)
info.bases = [obj]
try:
calculate_mro(info)
except MroError:
util.fail(
ctx.api, "Not able to calculate MRO for declarative base", ctx.call
)
obj = ctx.api.named_type(names.NAMED_TYPE_BUILTINS_OBJECT)
info.bases = [obj]
info.fallback_to_any = True
ctx.api.add_symbol_table_node(ctx.name, SymbolTableNode(GDEF, info))
util.set_is_base(info)
def _fill_in_decorators(ctx: ClassDefContext) -> None:
for decorator in ctx.cls.decorators:
# set the ".fullname" attribute of a class decorator
# that is a MemberExpr. This causes the logic in
# semanal.py->apply_class_plugin_hooks to invoke the
# get_class_decorator_hook for our "registry.map_class()"
# and "registry.as_declarative_base()" methods.
# this seems like a bug in mypy that these decorators are otherwise
# skipped.
if (
isinstance(decorator, nodes.CallExpr)
and isinstance(decorator.callee, nodes.MemberExpr)
and decorator.callee.name == "as_declarative_base"
):
target = decorator.callee
elif (
isinstance(decorator, nodes.MemberExpr)
and decorator.name == "mapped"
):
target = decorator
else:
continue
if isinstance(target.expr, NameExpr):
sym = ctx.api.lookup_qualified(
target.expr.name, target, suppress_errors=True
)
else:
continue
if sym and sym.node:
sym_type = get_proper_type(sym.type)
if isinstance(sym_type, Instance):
target.fullname = f"{sym_type.type.fullname}.{target.name}"
else:
# if the registry is in the same file as where the
# decorator is used, it might not have semantic
# symbols applied and we can't get a fully qualified
# name or an inferred type, so we are actually going to
# flag an error in this case that they need to annotate
# it. The "registry" is declared just
# once (or few times), so they have to just not use
# type inference for its assignment in this one case.
util.fail(
ctx.api,
"Class decorator called %s(), but we can't "
"tell if it's from an ORM registry. Please "
"annotate the registry assignment, e.g. "
"my_registry: registry = registry()" % target.name,
sym.node,
)
def _cls_decorator_hook(ctx: ClassDefContext) -> None:
_add_globals(ctx)
assert isinstance(ctx.reason, nodes.MemberExpr)
expr = ctx.reason.expr
assert isinstance(expr, nodes.RefExpr) and isinstance(expr.node, nodes.Var)
node_type = get_proper_type(expr.node.type)
assert (
isinstance(node_type, Instance)
and names.type_id_for_named_node(node_type.type) is names.REGISTRY
)
decl_class.scan_declarative_assignments_and_apply_types(ctx.cls, ctx.api)
def _base_cls_decorator_hook(ctx: ClassDefContext) -> None:
_add_globals(ctx)
cls = ctx.cls
_set_declarative_metaclass(ctx.api, cls)
util.set_is_base(ctx.cls.info)
decl_class.scan_declarative_assignments_and_apply_types(
cls, ctx.api, is_mixin_scan=True
)
def _declarative_mixin_hook(ctx: ClassDefContext) -> None:
_add_globals(ctx)
util.set_is_base(ctx.cls.info)
decl_class.scan_declarative_assignments_and_apply_types(
ctx.cls, ctx.api, is_mixin_scan=True
)
def _metaclass_cls_hook(ctx: ClassDefContext) -> None:
util.set_is_base(ctx.cls.info)
def _base_cls_hook(ctx: ClassDefContext) -> None:
_add_globals(ctx)
decl_class.scan_declarative_assignments_and_apply_types(ctx.cls, ctx.api)
def _queryable_getattr_hook(ctx: AttributeContext) -> Type:
# how do I....tell it it has no attribute of a certain name?
# can't find any Type that seems to match that
return ctx.default_attr_type
def _add_globals(ctx: Union[ClassDefContext, DynamicClassDefContext]) -> None:
"""Add __sa_DeclarativeMeta and __sa_Mapped symbol to the global space
for all class defs
"""
util.add_global(ctx, "sqlalchemy.orm", "Mapped", "__sa_Mapped")
def _set_declarative_metaclass(
api: SemanticAnalyzerPluginInterface, target_cls: ClassDef
) -> None:
info = target_cls.info
sym = api.lookup_fully_qualified_or_none(
"sqlalchemy.orm.decl_api.DeclarativeMeta"
)
assert sym is not None and isinstance(sym.node, TypeInfo)
info.declared_metaclass = info.metaclass_type = Instance(sym.node, [])
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