👷 Replace `mypy` with `ty` in precommit by svlandeg · Pull Request #1806 · fastapi/sqlmodel

svlandeg · 2026-03-09T16:58:48Z

Replace mypy with ty in precommit, lint.sh & pyproject.toml.
Type fixes to make ty happy

I originally set out to have mypy and ty run together in precommit, but for sqlmodel I would argue that perhaps we want to remove mypy alltogether already now, as it allows us to remove a lot of type: ignore statements that ty thinks are unnecessary anyway.

⚠️ This requires thorough review, I'm not super sure on all decisions taken here, cf 2 separate review comments below 👇

github-actions · 2026-03-09T17:01:03Z

📝 Docs preview

Last commit c49bf7f at: https://4d2e1793.sqlmodel.pages.dev

…rs are before it (invalid-legacy-positional-parameter)

svlandeg · 2026-03-10T10:11:37Z

scripts/generate_select.py

                t_type = f"_T{i}"
                t_var = f"_TCCA[{t_type}]"
-                arg = Arg(name=f"__ent{i}", annotation=t_var)
+                arg = Arg(name=f"_ent{i}", annotation=t_var)


ty complaints with:

warning[invalid-legacy-positional-parameter]: Invalid use of the legacy convention for positional-only parameters
--> sqlmodel\sql_expression_select_gen.py:132:5
|
130 | @overload
131 | def select(
132 | entity_0: _TScalar_0,
| -------- Prior parameter here was positional-or-keyword
133 | __ent1: _TCCA[_T1],
| ^^^^^^ Parameter name begins with __ but will not be treated as positional-only
134 | ) -> Select[tuple[_TScalar_0, _T1]]: ...
|
info: A parameter can only be positional-only if it precedes all positional-or-keyword parameters
info: rule invalid-legacy-positional-parameter is enabled by default

So basically we can't have __var if there is a scalar parameter in front of this one.

As a quick fix, I changed all double underscores to singles, but it feels a bit like a hack. We could also suppress the ty warning, but that also feels wrong...

I think just renaming it to single-underscored would be incorrect.
As I understand, double-underscored parameter names was a convention for position-only parameters before , / syntax was added in 3.8.

I suggest we update this to use names without leading underscores, and update template to add , / to each signature of select:

@overload -def select(__ent0: _TCCA[_T0]) -> SelectOfScalar[_T0]: ... +def select(__ent0: _TCCA[_T0], /) -> SelectOfScalar[_T0]: ... @overload -def select(__ent0: _TScalar_0) -> SelectOfScalar[_TScalar_0]: ... +def select(__ent0: _TScalar_0, /) -> SelectOfScalar[_TScalar_0]: ... # Generated overloads start {% for signature in signatures %} @overload def select( - {% for arg in signature[0] %}{{ arg.name }}: {{ arg.annotation }}, {% endfor %} + {% for arg in signature[0] %}{{ arg.name }}: {{ arg.annotation }}, {% endfor %} /, ) -> Select[tuple[{%for ret in signature[1] %}{{ ret }} {% if not loop.last %}, {% endif %}{% endfor %}]]: ... {% endfor %} # Generated overloads end

Alternatively we can leave __ent and rename entity_.. parameters to __entity_..

svlandeg · 2026-03-10T10:14:37Z

sqlmodel/main.py

-    def __setattr__(cls, name: str, value: Any) -> None:
+    def __setattr__(cls, key: str, value: Any) -> None:
        if is_table_model_class(cls):
-            DeclarativeMeta.__setattr__(cls, name, value)
+            DeclarativeMeta.__setattr__(cls, key, value)
        else:
-            super().__setattr__(name, value)
+            super().__setattr__(key, value)

-    def __delattr__(cls, name: str) -> None:
+    def __delattr__(cls, key: str) -> None:
        if is_table_model_class(cls):
-            DeclarativeMeta.__delattr__(cls, name)
+            DeclarativeMeta.__delattr__(cls, key)
        else:
-            super().__delattr__(name)
+            super().__delattr__(key)


ty said the original code violates the Liskov Substitution Principle.

ty is right about Liskov Substitution Principle violation, but I don't think we need to fix it this way.
object declares these methods with name parameter. So, using key here will not be correct.
This is actually minor issue as this is unlikely that these methods will be called with parameters passed by name.
So, I would revert changes and just ignore ty warning

# Conflicts: # pyproject.toml # uv.lock

YuriiMotov

Added a few suggestions in the comments. Please, take a look)

YuriiMotov · 2026-03-16T12:10:04Z

sqlmodel/main.py

-    def __setattr__(cls, name: str, value: Any) -> None:
+    def __setattr__(cls, key: str, value: Any) -> None:
        if is_table_model_class(cls):
-            DeclarativeMeta.__setattr__(cls, name, value)
+            DeclarativeMeta.__setattr__(cls, key, value)
        else:
-            super().__setattr__(name, value)
+            super().__setattr__(key, value)

-    def __delattr__(cls, name: str) -> None:
+    def __delattr__(cls, key: str) -> None:
        if is_table_model_class(cls):
-            DeclarativeMeta.__delattr__(cls, name)
+            DeclarativeMeta.__delattr__(cls, key)
        else:
-            super().__delattr__(name)
+            super().__delattr__(key)


ty is right about Liskov Substitution Principle violation, but I don't think we need to fix it this way.
object declares these methods with name parameter. So, using key here will not be correct.
This is actually minor issue as this is unlikely that these methods will be called with parameters passed by name.
So, I would revert changes and just ignore ty warning

YuriiMotov · 2026-03-16T13:42:55Z

sqlmodel/sql/_expression_select_cls.py

        its `WHERE` clause, joined to the existing clause via `AND`, if any.
        """
-        return super().where(*whereclause)  # type: ignore[arg-type]
+        return super().where(*whereclause)


It's ty's mistake that it doesn't notice type mismatch here. But I checked - passing bool argument works in runtime

YuriiMotov · 2026-03-16T14:21:48Z

scripts/generate_select.py

                t_type = f"_T{i}"
                t_var = f"_TCCA[{t_type}]"
-                arg = Arg(name=f"__ent{i}", annotation=t_var)
+                arg = Arg(name=f"_ent{i}", annotation=t_var)


I think just renaming it to single-underscored would be incorrect.
As I understand, double-underscored parameter names was a convention for position-only parameters before , / syntax was added in 3.8.

I suggest we update this to use names without leading underscores, and update template to add , / to each signature of select:

@overload -def select(__ent0: _TCCA[_T0]) -> SelectOfScalar[_T0]: ... +def select(__ent0: _TCCA[_T0], /) -> SelectOfScalar[_T0]: ... @overload -def select(__ent0: _TScalar_0) -> SelectOfScalar[_TScalar_0]: ... +def select(__ent0: _TScalar_0, /) -> SelectOfScalar[_TScalar_0]: ... # Generated overloads start {% for signature in signatures %} @overload def select( - {% for arg in signature[0] %}{{ arg.name }}: {{ arg.annotation }}, {% endfor %} + {% for arg in signature[0] %}{{ arg.name }}: {{ arg.annotation }}, {% endfor %} /, ) -> Select[tuple[{%for ret in signature[1] %}{{ ret }} {% if not loop.last %}, {% endif %}{% endfor %}]]: ... {% endfor %} # Generated overloads end

Alternatively we can leave __ent and rename entity_.. parameters to __entity_..

YuriiMotov · 2026-03-16T14:53:14Z

sqlmodel/main.py



-class_registry = weakref.WeakValueDictionary()  # type: ignore
+class_registry = weakref.WeakValueDictionary()


Do we even need this class_registry?
It's not used and after removing it all tests pass

add ty to lint, precommit, pyproject and uv lock

0251f0f

svlandeg added the internal label Mar 9, 2026

svlandeg self-assigned this Mar 9, 2026

svlandeg and others added 9 commits March 9, 2026 19:21

add type annotation to kwargs dict

a52380b

remove unnecessary type ignore statements

3203f83

🎨 Auto format

5d9dd59

avoid using double underscore when any positional-or-keyword paramete…

5c9b1d5

…rs are before it (invalid-legacy-positional-parameter)

one more

c1b0465

remove mypy

732847d

Merge branch 'main' into feat/ty

2f8efa3

use same names as upstream class

dc8593b

fix generator

1dceaa7

svlandeg commented Mar 10, 2026

View reviewed changes

svlandeg changed the title ~~👷 Add ty to precommit~~ 👷 Replace mypy with ty in precommit Mar 10, 2026

svlandeg marked this pull request as ready for review March 10, 2026 10:16

svlandeg removed their assignment Mar 10, 2026

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Merge branch 'main' into feat/ty

02cd800

# Conflicts: # pyproject.toml # uv.lock

github-actions bot removed the conflicts Automatically generated when a PR has a merge conflict label Mar 14, 2026

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github-actions bot added the conflicts Automatically generated when a PR has a merge conflict label Mar 15, 2026

svlandeg self-assigned this Mar 15, 2026

Merge branch 'main' into feat/ty

c49bf7f

# Conflicts: # pyproject.toml # uv.lock

github-actions bot removed the conflicts Automatically generated when a PR has a merge conflict label Mar 16, 2026

svlandeg removed their assignment Mar 16, 2026

svlandeg requested a review from YuriiMotov March 16, 2026 09:15

YuriiMotov reviewed Mar 16, 2026

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svlandeg self-assigned this Mar 16, 2026

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👷 Replace `mypy` with `ty` in precommit#1806

👷 Replace `mypy` with `ty` in precommit#1806
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		class_registry = weakref.WeakValueDictionary() # type: ignore
		class_registry = weakref.WeakValueDictionary()

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