version with pydantic inheritance passing all the tests

ormar/fields/base.py

@@ -0,0 +1,80 @@
+from typing import Any, Dict, List, Optional, TYPE_CHECKING
+
+import pydantic
+import sqlalchemy
+from pydantic import Field
+
+from ormar import ModelDefinitionError  # noqa I101
+
+if TYPE_CHECKING:  # pragma no cover
+    from ormar.models import Model
+
+
+def prepare_validator(type_):
+    def validate_model_field(value):
+        return isinstance(value, type_)
+
+    return validate_model_field
+
+
+class BaseField:
+    __type__ = None
+
+    column_type: sqlalchemy.Column
+    constraints: List = []
+
+    primary_key: bool
+    autoincrement: bool
+    nullable: bool
+    index: bool
+    unique: bool
+    pydantic_only: bool
+
+    default: Any
+    server_default: Any
+
+    @classmethod
+    def is_required(cls) -> bool:
+        return (
+                not cls.nullable and not cls.has_default() and not cls.is_auto_primary_key()
+        )
+
+    @classmethod
+    def default_value(cls):
+        if cls.is_auto_primary_key():
+            return Field(default=None)
+        if cls.has_default():
+            default = cls.default if cls.default is not None else cls.server_default
+            if callable(default):
+                return Field(default_factory=default)
+            else:
+                return Field(default=default)
+        return None
+
+    @classmethod
+    def has_default(cls):
+        return cls.default is not None or cls.server_default is not None
+
+    @classmethod
+    def is_auto_primary_key(cls) -> bool:
+        if cls.primary_key:
+            return cls.autoincrement
+        return False
+
+    @classmethod
+    def get_column(cls, name: str) -> sqlalchemy.Column:
+        return sqlalchemy.Column(
+            name,
+            cls.column_type,
+            *cls.constraints,
+            primary_key=cls.primary_key,
+            nullable=cls.nullable and not cls.primary_key,
+            index=cls.index,
+            unique=cls.unique,
+            default=cls.default,
+            server_default=cls.server_default,
+        )
+
+    @classmethod
+    def expand_relationship(cls, value: Any, child: "Model") -> Any:
+        return value