Validate embedded model fields.

django_mongodb/fields/embedded_model.py

@@ -15,6 +15,9 @@ def __init__(self, embedded_model, *args, **kwargs):
         stored. Like other relational fields, it may also be passed as a
         string.
         """
+        if not isinstance(embedded_model, str):
+            self._validate_embedded_field(self, embedded_model)
+
         self.embedded_model = embedded_model
         super().__init__(*args, **kwargs)
 
@@ -28,6 +31,14 @@ def deconstruct(self):
     def get_internal_type(self):
         return "EmbeddedModelField"
 
+    @staticmethod
+    def _validate_embedded_field(_, model):
+        for field in model._meta.local_fields:
+            if isinstance(field, models.ForeignKey | models.OneToOneField):
+                raise TypeError(
+                    f"Field of type {type(field)!r} is not supported within an EmbeddedModelField."
+                )
+
     def _set_model(self, model):
         """
         Resolve embedded model class once the field knows the model it belongs
@@ -48,6 +59,7 @@ def _resolve_lookup(_, resolved_model):
                 self.embedded_model = resolved_model
 
             lazy_related_operation(_resolve_lookup, model, self.embedded_model)
+            lazy_related_operation(self._validate_embedded_field, model, self.embedded_model)
 
     model = property(lambda self: self._model, _set_model)
 
@@ -139,7 +151,7 @@ def formfield(self, **kwargs):
 
 
 class KeyTransform(Transform):
-    def __init__(self, key_name, ref_field=None, *args, **kwargs):
+    def __init__(self, key_name, ref_field, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.key_name = str(key_name)
         self.ref_field = ref_field
@@ -195,7 +207,7 @@ def key_transform(self, compiler, connection):
 
 
 class KeyTransformFactory:
-    def __init__(self, key_name, ref_field=None):
+    def __init__(self, key_name, ref_field):
         self.key_name = key_name
         self.ref_field = ref_field
 

tests/model_fields_/test_embedded_model.py

@@ -8,6 +8,7 @@
     F,
     IntegerField,
     Max,
+    Model,
     OuterRef,
     Subquery,
     Sum,
@@ -21,6 +22,7 @@
     Author,
     Book,
     DecimalKey,
+    DecimalParent,
     EmbeddedModel,
     EmbeddedModelFieldModel,
     Library,
@@ -97,6 +99,16 @@ def test_embedded_field_with_foreign_conversion(self):
         # decimal_parent = DecimalParent.objects.create(child=decimal)
         EmbeddedModelFieldModel.objects.create(decimal_parent=decimal)
 
+    def test_foreign_key_in_embedded_object(self):
+        msg = (
+            "Field of type <class 'django.db.models.fields.related.ForeignKey'> "
+            "is not supported within an EmbeddedModelField."
+        )
+        with self.assertRaisesMessage(TypeError, msg):
+
+            class EmbeddedModelTest(Model):
+                decimal = EmbeddedModelField(DecimalParent, null=True, blank=True)
+
 
 class QueryingTests(TestCase):
     @classmethod