René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Improve error message for missing @schema decorator","articleBody":"If you forget to decorate a datajoint class with its schema, the error message is now more cryptic than it used to be.\r\n\r\n```python\r\nclass Mouse(dj.Manual):\r\n    definition = \"\"\"\r\n    mouse_id : int  \r\n    ----\r\n    dob  : date \r\n    sex  : enum('M', 'F', 'unknown')\r\n    \"\"\"\r\n    pass\r\n\r\nMouse()\r\n```\r\n```\r\n---------------------------------------------------------------------------\r\nAttributeError                            Traceback (most recent call last)\r\n/opt/conda/lib/python3.6/site-packages/IPython/core/formatters.py in __call__(self, obj)\r\n    700                 type_pprinters=self.type_printers,\r\n    701                 deferred_pprinters=self.deferred_printers)\r\n--\u003e 702             printer.pretty(obj)\r\n    703             printer.flush()\r\n    704             return stream.getvalue()\r\n\r\n/opt/conda/lib/python3.6/site-packages/IPython/lib/pretty.py in pretty(self, obj)\r\n    393                             if callable(meth):\r\n    394                                 return meth(obj, self, cycle)\r\n--\u003e 395             return _default_pprint(obj, self, cycle)\r\n    396         finally:\r\n    397             self.end_group()\r\n\r\n/opt/conda/lib/python3.6/site-packages/IPython/lib/pretty.py in _default_pprint(obj, p, cycle)\r\n    508     if _safe_getattr(klass, '__repr__', None) is not object.__repr__:\r\n    509         # A user-provided repr. Find newlines and replace them with p.break_()\r\n--\u003e 510         _repr_pprint(obj, p, cycle)\r\n    511         return\r\n    512     p.begin_group(1, '\u003c')\r\n\r\n/opt/conda/lib/python3.6/site-packages/IPython/lib/pretty.py in _repr_pprint(obj, p, cycle)\r\n    699     \"\"\"A pprint that just redirects to the normal repr function.\"\"\"\r\n    700     # Find newlines and replace them with p.break_()\r\n--\u003e 701     output = repr(obj)\r\n    702     for idx,output_line in enumerate(output.splitlines()):\r\n    703         if idx:\r\n\r\n/opt/conda/lib/python3.6/site-packages/datajoint/relational_operand.py in __repr__(self)\r\n    345 \r\n    346     def __repr__(self):\r\n--\u003e 347         return super().__repr__() if config['loglevel'].lower() == 'debug' else self.preview()\r\n    348 \r\n    349     def preview(self, limit=None, width=None):\r\n\r\n/opt/conda/lib/python3.6/site-packages/datajoint/relational_operand.py in preview(self, limit, width)\r\n    351         returns a preview of the contents of the relation.\r\n    352         \"\"\"\r\n--\u003e 353         heading = self.heading\r\n    354         rel = self.proj(*heading.non_blobs)\r\n    355         if limit is None:\r\n\r\n/opt/conda/lib/python3.6/site-packages/datajoint/base_relation.py in heading(self)\r\n     43             self._heading = Heading()  # instance-level heading\r\n     44         if not self._heading:  # lazy loading of heading\r\n---\u003e 45             self._heading.init_from_database(self.connection, self.database, self.table_name)\r\n     46         return self._heading\r\n     47 \r\n\r\n/opt/conda/lib/python3.6/site-packages/datajoint/heading.py in init_from_database(self, conn, database, table_name)\r\n    132         initialize heading from a database table.  The table must exist already.\r\n    133         \"\"\"\r\n--\u003e 134         info = conn.query('SHOW TABLE STATUS FROM `{database}` WHERE name=\"{table_name}\"'.format(\r\n    135             table_name=table_name, database=database), as_dict=True).fetchone()\r\n    136         if info is None:\r\n\r\nAttributeError: 'NoneType' object has no attribute 'query'\r\n\r\n---------------------------------------------------------------------------\r\nAttributeError                            Traceback (most recent call last)\r\n/opt/conda/lib/python3.6/site-packages/IPython/core/formatters.py in __call__(self, obj)\r\n    343             method = get_real_method(obj, self.print_method)\r\n    344             if method is not None:\r\n--\u003e 345                 return method()\r\n    346             return None\r\n    347         else:\r\n\r\n/opt/conda/lib/python3.6/site-packages/datajoint/relational_operand.py in _repr_html_(self)\r\n    373 \r\n    374     def _repr_html_(self):\r\n--\u003e 375         heading = self.heading\r\n    376         rel = self.proj(*heading.non_blobs)\r\n    377         info = heading.table_info\r\n\r\n/opt/conda/lib/python3.6/site-packages/datajoint/base_relation.py in heading(self)\r\n     43             self._heading = Heading()  # instance-level heading\r\n     44         if not self._heading:  # lazy loading of heading\r\n---\u003e 45             self._heading.init_from_database(self.connection, self.database, self.table_name)\r\n     46         return self._heading\r\n     47 \r\n\r\n/opt/conda/lib/python3.6/site-packages/datajoint/heading.py in init_from_database(self, conn, database, table_name)\r\n    132         initialize heading from a database table.  The table must exist already.\r\n    133         \"\"\"\r\n--\u003e 134         info = conn.query('SHOW TABLE STATUS FROM `{database}` WHERE name=\"{table_name}\"'.format(\r\n    135             table_name=table_name, database=database), as_dict=True).fetchone()\r\n    136         if info is None:\r\n\r\nAttributeError: 'NoneType' object has no attribute 'query'\r\n```","author":{"url":"https://github.com/dimitri-yatsenko","@type":"Person","name":"dimitri-yatsenko"},"datePublished":"2018-04-19T17:48:45.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/466/datajoint-python/issues/466"}