Foreign key is handled.

jedi/plugins/stdlib.py

@@ -21,7 +21,7 @@ from jedi.inference.arguments import \
 from jedi.inference import analysis
 from jedi.inference import compiled
 from jedi.inference.value.instance import \
-    AnonymousMethodExecutionContext, MethodExecutionContext
+    AnonymousMethodExecutionContext, MethodExecutionContext, TreeInstance
 from jedi.inference.base_value import ContextualizedNode, \
     NO_VALUES, ValueSet, ValueWrapper, LazyValueWrapper
 from jedi.inference.value import ClassValue, ModuleValue
@@ -810,8 +810,22 @@ def infer_django_field(cls, field):
         return DjangoModelField(model_instance_field_type, field).name
 
     if field_tree_instance.name.string_name == 'ForeignKey':
-        # TODO: infer related object class and make a filter for that class
+        if isinstance(field_tree_instance, TreeInstance):
-        return
+             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:
+                 # TODO: it has only one element in current state. Handle rest of elements.
+                 for value in lazy_values.infer():
+                     string = value.get_safe_value(default=None)
+                     if value.name.string_name == 'str':
+                         foreign_key_class_name = value._compiled_obj.get_safe_value()
+                         # TODO: it has only one element in current state. Handle rest of elements.
+                         for v in cls.parent_context.py__getattribute__(foreign_key_class_name):
+                             return DjangoModelField(v, field).name
+                     else:
+                         return DjangoModelField(value, field).name
+
+        raise Exception('Should be handled')
 
     if field_tree_instance.name.string_name == 'TimeField':
         model_instance_field_type, = cls.inference_state.import_module(('datetime',)).py__getattribute__('time')