René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Foreign key bug when no new attributes are added ","articleBody":"When declaring a foreign key with no new attributes, e.g.\r\n```python\r\n@schema\r\nclass A(dj.Manual):\r\n    definition = \"\"\"\r\n    a  : int\r\n    \"\"\"\r\n\r\n@schema\r\nclass B(dj.Manual):\r\n    definition = \"\"\"\r\n    -\u003e A\r\n    \"\"\"\r\n\r\n@schema\r\nclass C(dj.Manual):\r\n    definition = \"\"\"\r\n    -\u003e B\r\n    -\u003e A\r\n    \"\"\"\r\n```\r\nthe following error results\r\n```\r\n File \"test.py\", line 21, in \u003cmodule\u003e\r\n    class C(dj.Manual):\r\n  File \"/Users/dimitri/dev/datajoint-python/datajoint/schema.py\", line 196, in __call__\r\n    self.process_relation_class(cls, context=dict(self.context, **ext))\r\n  File \"/Users/dimitri/dev/datajoint-python/datajoint/schema.py\", line 172, in process_relation_class\r\n    instance.declare()\r\n  File \"/Users/dimitri/dev/datajoint-python/datajoint/base_relation.py\", line 55, in declare\r\n    declare(self.full_table_name, self.definition, self._context))\r\n  File \"/Users/dimitri/dev/datajoint-python/datajoint/declare.py\", line 126, in declare\r\n    attribute_sql, foreign_key_sql)\r\n  File \"/Users/dimitri/dev/datajoint-python/datajoint/declare.py\", line 82, in compile_foreign_key\r\n    if len(new_attrs) != len(ref_attrs):\r\nTypeError: object of type 'bool' has no len()\r\n```","author":{"url":"https://github.com/dimitri-yatsenko","@type":"Person","name":"dimitri-yatsenko"},"datePublished":"2017-10-05T17:49:56.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/370/datajoint-python/issues/370"}