Merge f8a7c80 into 68ef4b5

pylint_django/transforms/foreignkey.py

@@ -1,4 +1,5 @@
-from astroid import nodes, InferenceError, inference_tip, UseInferenceDefault
+from astroid import MANAGER, nodes, InferenceError, inference_tip, UseInferenceDefault
+from pylint_django.utils import node_is_subclass
 from pylint_django.compat import ClassDef, instantiate_class, Attribute
 
 
@@ -33,6 +34,21 @@ def infer_key_classes(node, context=None):
             else:
                 if key_cls is not None:
                     break
+        elif isinstance(arg, nodes.Const):
+            try:
+                model_name = arg.value.split('.')[-1]  # can be 'Model' or 'app.Model'
+            except AttributeError:
+                break
+
+            for module in MANAGER.astroid_cache.values():
+                if model_name in module.locals:
+                    class_defs = [
+                        module_node for module_node in module.lookup(model_name)[1]
+                        if isinstance(module_node, nodes.ClassDef)
+                        and node_is_subclass(module_node, 'django.db.models.base.Model')
+                    ]
+                    if class_defs:
+                        return iter([instantiate_class(class_defs[0])()])
     else:
         raise UseInferenceDefault
     return iter([instantiate_class(key_cls)()])

test/input/func_noerror_foreignkeys.py

@@ -17,7 +17,7 @@ class ISBN(models.Model):
 
 class Book(models.Model):
     book_name = models.CharField(max_length=100)
-    author = models.ForeignKey(Author, on_delete=models.CASCADE)
+    author = models.ForeignKey('Author', on_delete=models.CASCADE)
     isbn = models.OneToOneField(ISBN, on_delete=models.CASCADE)
 
     def get_isbn(self):
@@ -47,3 +47,12 @@ class UserProfile(models.Model):
 
     def get_username(self):
         return self.user.username
+
+
+class UserPreferences(models.Model):
+    """
+        Used for testing FK which refers to another model by
+        string, not model class, see
+        https://github.com/landscapeio/pylint-django/issues/35
+    """
+    user = ForeignKey('User', on_delete=models.CASCADE)