✨ Support SQLAlchemy keyed dict models

sqlmodel/_compat.py

@@ -164,6 +164,9 @@ def get_relationship_to(
         # If a list, then also get the real field
         elif origin is list:
             use_annotation = get_args(annotation)[0]
+        # If a dict, then use the value type
+        elif origin is dict:
+            use_annotation = get_args(annotation)[1]
 
         return get_relationship_to(
             name=name, rel_info=rel_info, annotation=use_annotation

tests/test_attribute_keyed_dict.py

@@ -0,0 +1,48 @@
+from enum import Enum
+from typing import Dict, Optional
+
+from sqlalchemy.orm.collections import attribute_keyed_dict
+from sqlmodel import Field, Index, Relationship, Session, SQLModel, create_engine
+
+
+def test_attribute_keyed_dict_works(clear_sqlmodel):
+    class Color(str, Enum):
+        Orange = "Orange"
+        Blue = "Blue"
+
+    class Child(SQLModel, table=True):
+        __tablename__ = "children"
+        __table_args__ = (
+            Index("ix_children_parent_id_color", "parent_id", "color", unique=True),
+        )
+
+        id: Optional[int] = Field(primary_key=True, default=None)
+        parent_id: int = Field(foreign_key="parents.id")
+        color: Color
+        value: int
+
+    class Parent(SQLModel, table=True):
+        __tablename__ = "parents"
+
+        id: Optional[int] = Field(primary_key=True, default=None)
+        children_by_color: Dict[Color, Child] = Relationship(
+            sa_relationship_kwargs={"collection_class": attribute_keyed_dict("color")}
+        )
+
+    engine = create_engine("sqlite://")
+    SQLModel.metadata.create_all(engine)
+    with Session(engine) as session:
+        parent = Parent()
+        session.add(parent)
+        session.commit()
+        session.refresh(parent)
+        session.add(Child(parent_id=parent.id, color=Color.Orange, value=1))
+        session.add(Child(parent_id=parent.id, color=Color.Blue, value=2))
+        session.commit()
+        session.refresh(parent)
+        assert parent.children_by_color[Color.Orange].parent_id == parent.id
+        assert parent.children_by_color[Color.Orange].color == Color.Orange
+        assert parent.children_by_color[Color.Orange].value == 1
+        assert parent.children_by_color[Color.Blue].parent_id == parent.id
+        assert parent.children_by_color[Color.Blue].color == Color.Blue
+        assert parent.children_by_color[Color.Blue].value == 2