feat: add field overrides

polyfactory/factories/base.py

@@ -50,7 +50,7 @@
     RANDOMIZE_COLLECTION_LENGTH,
 )
 from polyfactory.exceptions import ConfigurationException, MissingBuildKwargException, ParameterException
-from polyfactory.field_meta import Null
+from polyfactory.field_meta import FieldMeta, Null
 from polyfactory.fields import Fixture, Ignore, PostGenerated, Require, Use
 from polyfactory.utils.helpers import (
     flatten_annotation,
@@ -82,7 +82,7 @@
 if TYPE_CHECKING:
     from typing_extensions import TypeGuard
 
-    from polyfactory.field_meta import Constraints, FieldMeta
+    from polyfactory.field_meta import Constraints
     from polyfactory.persistence import AsyncPersistenceProtocol, SyncPersistenceProtocol
 
 
@@ -914,7 +914,7 @@ def _check_declared_fields_exist_in_model(cls) -> None:
                 raise ConfigurationException(error_message)
 
     @classmethod
-    def process_kwargs(cls, **kwargs: Any) -> dict[str, Any]:
+    def process_kwargs(cls, **kwargs: Any) -> dict[str, Any]:  # noqa: C901
         """Process the given kwargs and generate values for the factory's model.
 
         :param kwargs: Any build kwargs.
@@ -931,7 +931,12 @@ def process_kwargs(cls, **kwargs: Any) -> dict[str, Any]:
         for field_meta in cls.get_model_fields():
             field_build_parameters = cls.extract_field_build_parameters(field_meta=field_meta, build_args=kwargs)
             if cls.should_set_field_value(field_meta, **kwargs) and not cls.should_use_default_value(field_meta):
-                if hasattr(cls, field_meta.name) and not hasattr(BaseFactory, field_meta.name):
+                field_value = getattr(cls, field_meta.name, Null)
+                if (
+                    field_value is not Null
+                    and not hasattr(BaseFactory, field_meta.name)
+                    and not isinstance(field_value, FieldMeta)
+                ):
                     field_value = getattr(cls, field_meta.name)
                     if isinstance(field_value, Ignore):
                         continue
@@ -951,6 +956,16 @@ def process_kwargs(cls, **kwargs: Any) -> dict[str, Any]:
                     )
                     continue
 
+                if isinstance(field_value, FieldMeta):
+                    if field_value.annotation is not Null:
+                        field_meta.annotation = field_value.annotation
+                        field_meta.children = field_value.children
+
+                    if field_value.constraints:
+                        if field_meta.constraints is None:
+                            field_meta.constraints = {}
+                        field_meta.constraints.update(field_value.constraints)
+
                 field_result = cls.get_field_value(
                     field_meta,
                     field_build_parameters=field_build_parameters,

polyfactory/fields.py

@@ -1,10 +1,14 @@
 from __future__ import annotations
 
-from typing import Any, Callable, Generic, TypedDict, TypeVar, cast
+from typing import TYPE_CHECKING, Any, Callable, Generic, TypedDict, TypeVar, cast
 
-from typing_extensions import ParamSpec
+from typing_extensions import ParamSpec, Unpack
 
 from polyfactory.exceptions import ParameterException
+from polyfactory.field_meta import FieldMeta, Null
+
+if TYPE_CHECKING:
+    from polyfactory.field_meta import Constraints
 
 T = TypeVar("T")
 P = ParamSpec("P")
@@ -114,3 +118,7 @@ def to_value(self) -> Any:
 
         msg = "fixture has not been registered using the register_factory decorator"
         raise ParameterException(msg)
+
+
+def Field(annotation: Any = Null, **constraints: Unpack[Constraints]) -> FieldMeta:  # noqa: N802
+    return FieldMeta.from_type(annotation, constraints=constraints)

tests/test_factory_fields.py

@@ -1,6 +1,6 @@
 import random
 from datetime import datetime, timedelta
-from typing import Any, Optional, Union
+from typing import Any, Literal, Optional, Union
 
 import pytest
 
@@ -9,7 +9,7 @@
 from polyfactory.decorators import post_generated
 from polyfactory.exceptions import ConfigurationException, MissingBuildKwargException
 from polyfactory.factories.pydantic_factory import ModelFactory
-from polyfactory.fields import Ignore, PostGenerated, Require, Use
+from polyfactory.fields import Field, Ignore, PostGenerated, Require, Use
 
 
 def test_use() -> None:
@@ -202,3 +202,24 @@ class NoFieldModel(BaseModel):
         match="unknown_field is declared on the factory NoFieldModelFactory but it is not part of the model NoFieldModel",
     ):
         ModelFactory.create_factory(NoFieldModel, bases=None, __check_model__=True, unknown_field=factory_field)
+
+
+def test_field() -> None:
+    class Model(BaseModel):
+        a: int
+        b: Union[str, None]
+        complex_type: list[tuple[int, int]]
+
+    class Factory(ModelFactory[Model]):
+        a = Field(ge=1, le=2)
+        b = Field(annotation=None)
+        complex_type = Field(
+            annotation=list[tuple[Literal[1], Literal[2]]],
+            min_length=2,
+            max_length=2,
+        )
+
+    result = Factory.build()
+    assert 1 <= result.a <= 2
+    assert result.b is None
+    assert result.complex_type == [(1, 2), (1, 2)]