Move lazy reference resolving to its own helper function

mypy_django_plugin/lib/helpers.py

@@ -13,6 +13,7 @@
     AssignmentStmt,
     Block,
     ClassDef,
+    Context,
     Expression,
     MemberExpr,
     MypyFile,
@@ -420,3 +421,30 @@ def is_abstract_model(model: TypeInfo) -> bool:
 
     metadata["is_abstract_model"] = False
     return False
+
+
+def resolve_lazy_reference(
+    reference: str, *, api: Union[TypeChecker, SemanticAnalyzer], django_context: "DjangoContext", ctx: Context
+) -> Optional[TypeInfo]:
+    """
+    Attempts to resolve a lazy reference(e.g. "<app_label>.<object_name>") to a
+    'TypeInfo' instance.
+    """
+    if "." not in reference:
+        # <object_name> -- needs prefix of <app_label>. We can't implicitly solve
+        # what app label this should be, yet.
+        return None
+
+    # Reference conforms to the structure of a lazy reference: '<app_label>.<object_name>'
+    fullname = django_context.model_class_fullnames_by_label.get(reference)
+    if fullname is not None:
+        model_info = lookup_fully_qualified_typeinfo(api, fullname)
+        if model_info is not None:
+            return model_info
+        elif isinstance(api, SemanticAnalyzer) and not api.final_iteration:
+            # Getting this far, where Django matched the reference but we still can't
+            # find it, we want to defer
+            api.defer()
+    else:
+        api.fail("Could not match lazy reference with any model", ctx)
+    return None

mypy_django_plugin/transformers/fields.py

@@ -239,26 +239,9 @@ def get_model_from_expression(
         ):
             return Instance(expr.node, [])
     elif isinstance(expr, StrExpr):
-        if "." not in expr.value:
-            # <object_name> -- needs prefix of <app_label>. We can't implicitly solve
-            # what app label this should be, yet.
-            api.fail("Could not resolve lazy reference without an app label", expr)
-            api.note(
-                ("Try to use a reference explicitly prefixed with app label:" f' "<app_label>.{expr.value}" instead'),
-                expr,
-            )
-            return None
-
-        # Expression conforms to the structure of a lazy reference: '<app_label>.<object_name>'
-        fullname = django_context.model_class_fullnames_by_label.get(expr.value)
-        if fullname is not None:
-            model_info = helpers.lookup_fully_qualified_typeinfo(api, fullname)
-            if model_info is not None:
-                return Instance(model_info, [])
-            elif isinstance(api, SemanticAnalyzer) and not api.final_iteration:
-                # Getting this far, where Django matched the reference but we still can't
-                # find it, we want to defer
-                api.defer()
+        model_info = helpers.resolve_lazy_reference(expr.value, api=api, django_context=django_context, ctx=expr)
+        if model_info is not None:
+            return Instance(model_info, [])
 
     return None
 

tests/typecheck/fields/test_related.yml

@@ -1148,11 +1148,7 @@
         main:2: note: Revealed type is "django.db.models.fields.related_descriptors.ManyToManyDescriptor[Any]"
         main:3: note: Revealed type is "django.db.models.fields.related_descriptors.ManyRelatedManager[Any]"
         myapp/models/child:5: error: Need type annotation for "parents"
-        myapp/models/child:5: error: Could not resolve lazy reference without an app label
-        myapp/models/child:5: note: Try to use a reference explicitly prefixed with app label: "<app_label>.Parent" instead
         myapp/models/child:6: error: Need type annotation for "other_parents"
-        myapp/models/child:6: error: Could not resolve lazy reference without an app label
-        myapp/models/child:6: note: Try to use a reference explicitly prefixed with app label: "<app_label>.Parent" instead
     installed_apps:
         -   myapp
     files: