Prevent EmbeddedJsonModel from generating primary keys (#797)

EmbeddedJsonModels are stored as part of their parent document, not as
separate Redis keys, so they don't need primary keys.

Fixes #496

Author: abrookins

aredis_om/model/model.py

@@ -2552,6 +2552,14 @@ class Config:
             # Set up PrimaryKeyAccessor descriptor for .pk access
             setattr(new_class, "pk", PrimaryKeyAccessor())
 
+        # For embedded models, clear the primary_key from meta since they don't
+        # need primary keys - they're stored as part of their parent document,
+        # not as separate Redis keys. This fixes GitHub issue #496.
+        # Note: We keep the pk field in model_fields but the validator will
+        # return None and model_dump will exclude it.
+        if getattr(new_class._meta, "embedded", False):
+            new_class._meta.primary_key = None
+
         if not getattr(new_class._meta, "global_key_prefix", None):
             new_class._meta.global_key_prefix = getattr(
                 base_meta, "global_key_prefix", ""
@@ -2770,6 +2778,9 @@ async def expire(
 
         @field_validator("pk", mode="after")
         def validate_pk(cls, v):
+            # Skip pk generation for embedded models - they don't need primary keys
+            if getattr(cls._meta, "embedded", False):
+                return None
             if not v or isinstance(v, ExpressionProxy):
                 v = cls._meta.primary_key_creator_cls().create_pk()
             return v
@@ -2778,13 +2789,24 @@ def validate_pk(cls, v):
 
         @field_validator("pk")
         def validate_pk(cls, v):
+            # Skip pk generation for embedded models - they don't need primary keys
+            if getattr(cls._meta, "embedded", False):
+                return None
             if not v or isinstance(v, ExpressionProxy):
                 v = cls._meta.primary_key_creator_cls().create_pk()
             return v
 
     @classmethod
     def validate_primary_key(cls):
-        """Check for a primary key. We need one (and only one)."""
+        """Check for a primary key. We need one (and only one).
+
+        Embedded models are exempt from this check since they don't need
+        primary keys - they're stored as part of their parent document.
+        """
+        # Skip validation for embedded models - they don't need primary keys
+        if getattr(cls._meta, "embedded", False):
+            return
+
         primary_keys = 0
         for name, field in cls.model_fields.items():
             if (
@@ -3823,5 +3845,17 @@ def schema_for_type(
 
 
 class EmbeddedJsonModel(JsonModel, abc.ABC):
+    """
+    A model intended to be embedded within a JsonModel.
+
+    EmbeddedJsonModels are stored as part of their parent document, not as
+    separate Redis keys, so they do not need or generate primary keys.
+
+    The pk field is excluded from serialization by default.
+    """
+
+    # Override pk to exclude it from serialization - embedded models don't need pks
+    pk: Optional[str] = Field(default=None, exclude=True)
+
     class Meta:
         embedded = True

redis_om/__init__.py

@@ -19,6 +19,7 @@
 )
 from .model.types import Coordinates, GeoFilter
 
+
 # Backward compatibility alias - deprecated, use SchemaDetector or SchemaMigrator
 Migrator = SchemaDetector
 

tests/test_json_model.py

@@ -892,6 +892,9 @@ async def test_schema(m, key_prefix):
     # We need to build the key prefix because it will differ based on whether
     # these tests were copied into the tests_sync folder and unasynce'd.
     key_prefix = m.Member.make_key(m.Member._meta.primary_key_pattern.format(pk=""))
+    # Note: EmbeddedJsonModel pk fields are not included in the schema since
+    # embedded models don't need primary keys (they're stored as part of their
+    # parent document, not as separate Redis keys). See GitHub issue #496.
     assert m.Member.redisearch_schema() == (
         f"ON JSON PREFIX 1 {key_prefix} SCHEMA "
         "$.pk AS pk TAG SEPARATOR | "
@@ -901,13 +904,9 @@ async def test_schema(m, key_prefix):
         "$.age AS age NUMERIC "
         "$.bio AS bio TAG SEPARATOR | "
         "$.bio AS bio_fts TEXT "
-        "$.address.pk AS address_pk TAG SEPARATOR | "
         "$.address.city AS address_city TAG SEPARATOR | "
         "$.address.postal_code AS address_postal_code TAG SEPARATOR | "
-        "$.address.note.pk AS address_note_pk TAG SEPARATOR | "
         "$.address.note.description AS address_note_description TAG SEPARATOR | "
-        "$.orders[*].pk AS orders_pk TAG SEPARATOR | "
-        "$.orders[*].items[*].pk AS orders_items_pk TAG SEPARATOR | "
         "$.orders[*].items[*].name AS orders_items_name TAG SEPARATOR |"
     )