support str|None , mapped_column, AnyURL

sqlmodel/main.py

@@ -11,6 +11,7 @@ from pathlib import Path
 from typing import (
     AbstractSet,
     Any,
+    Annotated, 
     Callable,
     ClassVar,
     Dict,
@@ -26,7 +27,9 @@ from typing import (
     Union,
     cast,
 )
+import types
 
+import pydantic
 from pydantic import BaseModel
 from pydantic._internal._fields import PydanticGeneralMetadata
 from pydantic._internal._model_construction import ModelMetaclass
@@ -40,6 +43,7 @@ from sqlalchemy.orm import RelationshipProperty, declared_attr, registry, relati
 from sqlalchemy.orm.attributes import set_attribute
 from sqlalchemy.orm.decl_api import DeclarativeMeta
 from sqlalchemy.orm.instrumentation import is_instrumented
+from sqlalchemy.orm.properties import MappedColumn
 from sqlalchemy.sql.schema import MetaData
 from sqlalchemy.sql.sqltypes import LargeBinary, Time
 
@@ -166,6 +170,18 @@ def Field(
     schema_extra: Optional[Dict[str, Any]] = None,
 ) -> Any:
     current_schema_extra = schema_extra or {}
+    if default is PydanticUndefined:
+        if type(sa_column) is types.FunctionType: #lambda 
+            sa_column_ = sa_column()
+        else:
+            sa_column_ = sa_column
+            
+        #assert type(sa_column) is Column:
+        if isinstance(sa_column_, Column) and sa_column_.server_default is not None:
+            default_value =  sa_column_.server_default.arg
+            if issubclass( type(sa_column_.type), Integer):
+                default = int(default_value)
+
     field_info = FieldInfo(
         default,
         default_factory=default_factory,
@@ -408,14 +424,27 @@ class SQLModelMetaclass(ModelMetaclass, DeclarativeMeta):
 def get_sqlalchemy_type(field: FieldInfo) -> Any:
     type_: Optional[type] = field.annotation
 
-    # Resolve Optional fields
-    if type_ is not None and get_origin(type_) is Union:
+    # Resolve Optional/Union fields
+    if type_ is not None and get_origin(type_) in (types.UnionType, Union):
         bases = get_args(type_)
         if len(bases) > 2:
             raise RuntimeError(
                 "Cannot have a (non-optional) union as a SQL alchemy field"
             )
         type_ = bases[0]
+    # Resolve Annoted fields,
+    # like typing.Annotated[pydantic_core._pydantic_core.Url, 
+    # UrlConstraints(max_length=512, 
+    # allowed_schemes=['smb', 'ftp', 'file']) ]
+    if type_ is pydantic.AnyUrl:
+        meta =  field.metadata[0]
+        return AutoString(length=meta.max_length)
+    
+    if  get_origin(type_) is Annotated:
+        type2 = type_.__args__[0]
+        if type2 is pydantic.AnyUrl:
+            meta =  type_.__metadata__[0]
+            return AutoString(length=meta.max_length)
 
     # The 3rd is PydanticGeneralMetadata
     metadata = _get_field_metadata(field)
@@ -466,7 +495,7 @@ def get_sqlalchemy_type(field: FieldInfo) -> Any:
 
 def get_column_from_field(field: FieldInfo) -> Column:  # type: ignore
     sa_column = getattr(field, "sa_column", PydanticUndefined)
-    if isinstance(sa_column, Column):
+    if isinstance(sa_column, Column) or isinstance(sa_column, MappedColumn) :
         return sa_column
     sa_type = get_sqlalchemy_type(field)
     primary_key = getattr(field, "primary_key", False)