Defer pydantic v1 import until it actually being used (#1676)

Author: uriyyo

fastapi_pagination/customization.py

@@ -64,11 +64,14 @@
     make_field_optional,
     make_field_required,
 )
-from .pydantic.v1 import BaseModelV1, ConfiguredBaseModelV1, FieldInfoV1, GenericModelV1, UndefinedV1, create_model_v1
 from .pydantic.v2 import FieldV2, UndefinedV2, is_pydantic_v2_model
 from .types import Cursor
 from .utils import get_caller
 
+if TYPE_CHECKING:
+    from .pydantic.v1 import BaseModelV1
+
+
 ClsNamespace: TypeAlias = dict[str, Any]
 PageCls: TypeAlias = "type[AbstractPage[Any]]"
 
@@ -530,6 +533,11 @@ def model_post_init(_self: AbstractPage[Any], context: Any, /) -> None:
 
 
 def _convert_v2_field_to_v1(field_v2: FieldV2) -> tuple[Any, Any]:
+    from .pydantic.v1 import (
+        FieldInfoV1,
+        UndefinedV1,
+    )
+
     default = field_v2.default
     if default is UndefinedV2:
         default = UndefinedV1
@@ -549,6 +557,13 @@ def _convert_v2_field_to_v1(field_v2: FieldV2) -> tuple[Any, Any]:
 
 
 def _convert_v2_page_cls_to_v1(page_cls: type[AbstractPage], /) -> BaseModelV1:
+    from .pydantic.v1 import (
+        BaseModelV1,
+        ConfiguredBaseModelV1,
+        GenericModelV1,
+        create_model_v1,
+    )
+
     assert issubclass(page_cls, AbstractPage)
 
     _create = page_cls.create.__func__  # type: ignore[attr-defined]

fastapi_pagination/pydantic/common.py

@@ -7,14 +7,15 @@
     "make_field_required",
 ]
 
+import inspect
 from copy import copy
 from functools import singledispatch
 from typing import Annotated, Any, TypeVar, cast
 
 from fastapi_pagination.typing_utils import remove_optional_from_tp
 
+from .consts import IS_PYDANTIC_V2
 from .types import AnyBaseModel, AnyField
-from .v1 import FieldV1
 from .v2 import FieldV2, is_pydantic_v2_model
 
 TAny = TypeVar("TAny")
@@ -37,16 +38,25 @@ def get_model_fields(model: type[AnyBaseModel], /) -> dict[str, AnyField]:
 
 
 def is_pydantic_field(field: Any, /) -> bool:
-    return isinstance(field, (FieldV1, FieldV2))
+    return is_pydantic_v2_field(field) or is_pydantic_v1_field(field)
 
 
-@singledispatch
-def make_field_optional(field: Any) -> Any:  # pragma: no cover
-    raise ValueError(f"Invalid field type {field!r}")
+def is_pydantic_v2_field(field: Any, /) -> bool:
+    return isinstance(field, FieldV2)
 
 
-@make_field_optional.register
-def _(field: FieldV1, /) -> Any:
+def is_pydantic_v1_field(field: Any, /) -> bool:
+    cls = type(field)
+
+    names = {"pydantic.v1.fields.ModelField"}
+    if not IS_PYDANTIC_V2:
+        names.add("pydantic.fields.ModelField")
+
+    return any(f"{mro_cls.__module__}.{mro_cls.__qualname__}" in names for mro_cls in inspect.getmro(cls))
+
+
+@singledispatch
+def make_field_optional(field: Any) -> Any:  # pragma: no cover
     return None
 
 
@@ -63,11 +73,6 @@ def _(field: FieldV2, /) -> Any:
 
 @singledispatch
 def make_field_required(field: Any, /) -> Any:  # pragma: no cover
-    raise ValueError(f"Invalid field type {field!r}")
-
-
-@make_field_required.register
-def _(field: FieldV1, /) -> Any:
     field = copy(field)
     field.required = True
     field.default = ...
@@ -89,11 +94,6 @@ def _(field: FieldV2, /) -> Any:
 
 @singledispatch
 def get_field_tp(field: Any, /) -> Any:  # pragma: no cover
-    raise ValueError(f"Invalid field type {field!r}")
-
-
-@get_field_tp.register
-def _(field: FieldV1, /) -> Any:
     return field.type_
 
 

fastapi_pagination/pydantic/types.py

@@ -5,14 +5,20 @@
     "LatestGenericModel",
 ]
 
-from typing import TypeAlias
+from typing import TYPE_CHECKING, Any, TypeAlias
 
 from .consts import IS_PYDANTIC_V2
-from .v1 import BaseModelV1, FieldV1
-from .v2 import BaseModelV2, FieldV2
 
-AnyBaseModel: TypeAlias = BaseModelV1 | BaseModelV2
-AnyField: TypeAlias = FieldV1 | FieldV2
+if TYPE_CHECKING:
+    from .v1 import BaseModelV1, FieldV1
+    from .v2 import BaseModelV2, FieldV2
+
+    AnyBaseModel: TypeAlias = BaseModelV1 | BaseModelV2
+    AnyField: TypeAlias = FieldV1 | FieldV2
+else:
+    AnyBaseModel = Any
+    AnyField = Any
+
 
 if IS_PYDANTIC_V2:
     from .v2 import ConfiguredBaseModelV2 as LatestConfiguredBaseModel

fastapi_pagination/pydantic/v2.py

@@ -39,9 +39,7 @@ def is_pydantic_v2_model(model_cls: type[Any]) -> TypeIs[type[BaseModelV2]]:
     if not IS_PYDANTIC_V2:
         return False
 
-    from .v1 import BaseModelV1
-
-    return not lenient_issubclass(model_cls, BaseModelV1)
+    return lenient_issubclass(model_cls, BaseModelV2)
 
 
 class ConfiguredBaseModelV2(BaseModelV2):

tests/test_customization.py

@@ -367,3 +367,12 @@ def test_use_pydantic_v1():
     ]
 
     assert issubclass(CustomPage, BaseModelV1)
+
+    page = CustomPage[int].create(
+        items=["1", "2", "3"],
+        params=CustomPage.__params_type__(),
+        total=3,
+    )
+
+    assert page.items == [1, 2, 3]
+    assert page.total == 3