Fix ForeignKey issues with invalid values

jedi/plugins/django.py

@@ -48,10 +48,11 @@ mapping = {
 
 
 def _infer_scalar_field(cls, field, field_tree_instance):
-    if field_tree_instance.name.string_name not in mapping:
+    try:
+        module_name, attribute_name = mapping[field_tree_instance.name.string_name]
+    except KeyError:
         return None
 
-    module_name, attribute_name = mapping[field_tree_instance.name.string_name]
     if module_name is None:
         module = cls.inference_state.builtins_module
     else:
@@ -69,6 +70,7 @@ def _infer_field(cls, field):
 
     if field_tree_instance.name.string_name == 'ForeignKey':
         if isinstance(field_tree_instance, TreeInstance):
+            # TODO private access..
             argument_iterator = field_tree_instance._arguments.unpack()
             key, lazy_values = next(argument_iterator, (None, None))
             if key is None and lazy_values is not None:
@@ -77,7 +79,7 @@ def _infer_field(cls, field):
                         foreign_key_class_name = value.get_safe_value()
                         for v in cls.parent_context.py__getattribute__(foreign_key_class_name):
                             return DjangoModelField(v, field)
-                    else:
+                    elif value.is_class():
                         return DjangoModelField(value, field)
 
     debug.dbg('django plugin: fail to infer `%s` from class `%s`',

test/completion/django.py

@@ -14,6 +14,8 @@ class Category(models.Model):
 
 class BusinessModel(models.Model):
     category_fk = models.ForeignKey(Category)
+    category_fk2 = models.ForeignKey('Category')
+    category_fk3 = models.ForeignKey(1)
     integer_field = models.IntegerField()
     big_integer_field = models.BigIntegerField()
     positive_integer_field = models.PositiveIntegerField()
@@ -63,9 +65,17 @@ model_instance.duration_field
 model_instance.date_field
 #? datetime.datetime()
 model_instance.date_time_field
+
 #? Category()
 model_instance.category_fk
 #? str()
 model_instance.category_fk.category_name
+#? Category()
+model_instance.category_fk2
+#? str()
+model_instance.category_fk2.category_name
+#? models.ForeignKey()
+model_instance.category_fk3
+
 #? models.ManyToManyField()
 model_instance.tags_m2m