add overwriting pydantic types #311

ormar/fields/base.py

@@ -31,6 +31,7 @@ class BaseField(FieldInfo):
 
     def __init__(self, **kwargs: Any) -> None:
         self.__type__: type = kwargs.pop("__type__", None)
+        self.__pydantic_type__: type = kwargs.pop("__pydantic_type__", None)
         self.__sample__: type = kwargs.pop("__sample__", None)
         self.related_name = kwargs.pop("related_name", None)
 

ormar/fields/foreign_key.py

@@ -143,12 +143,14 @@ def validate_not_allowed_fields(kwargs: Dict) -> None:
     encrypt_secret = kwargs.pop("encrypt_secret", None)
     encrypt_backend = kwargs.pop("encrypt_backend", None)
     encrypt_custom_backend = kwargs.pop("encrypt_custom_backend", None)
+    overwrite_pydantic_type = kwargs.pop("overwrite_pydantic_type", None)
 
     not_supported = [
         default,
         encrypt_secret,
         encrypt_backend,
         encrypt_custom_backend,
+        overwrite_pydantic_type,
     ]
     if any(x is not None for x in not_supported):
         raise ModelDefinitionError(

ormar/fields/model_fields.py

@@ -84,8 +84,13 @@ class ModelFieldFactory:
         encrypt_backend = kwargs.pop("encrypt_backend", EncryptBackends.NONE)
         encrypt_custom_backend = kwargs.pop("encrypt_custom_backend", None)
 
+        overwrite_pydantic_type = kwargs.pop("overwrite_pydantic_type", None)
+
         namespace = dict(
             __type__=cls._type,
+            __pydantic_type__=overwrite_pydantic_type
+            if overwrite_pydantic_type is not None
+            else cls._type,
             __sample__=cls._sample,
             alias=kwargs.pop("name", None),
             name=None,

ormar/models/helpers/pydantic.py

@@ -5,8 +5,8 @@ import pydantic
 from pydantic.fields import ModelField
 from pydantic.utils import lenient_issubclass
 
-from ormar.fields import BaseField  # noqa: I100, I202
-from ormar.exceptions import ModelDefinitionError
+from ormar.exceptions import ModelDefinitionError  # noqa: I100, I202
+from ormar.fields import BaseField
 
 if TYPE_CHECKING:  # pragma no cover
     from ormar import Model
@@ -84,9 +84,15 @@ def populate_pydantic_default_values(attrs: Dict) -> Tuple[Dict, Dict]:
     for field_name, field in potential_fields.items():
         field.name = field_name
         model_fields[field_name] = field
-        attrs["__annotations__"][field_name] = (
+        default_type = (
             field.__type__ if not field.nullable else Optional[field.__type__]
         )
+        overwrite_type = (
+            field.__pydantic_type__
+            if field.__type__ != field.__pydantic_type__
+            else None
+        )
+        attrs["__annotations__"][field_name] = overwrite_type or default_type
     return attrs, model_fields