Cast dict_values To A list

[jamesmcclain]

This resolves the following issue that I observed on Python 3:

[IPKernelApp] ERROR | Exception opening comm with target: geonotebook
Traceback (most recent call last):
  File "/usr/lib/python3.4/site-packages/ipykernel/comm/manager.py", line 90, in comm_open
    f(comm, msg)
  File "/home/hadoop/.local/lib/python3.4/site-packages/geonotebook/kernel.py", line 534, in handle_comm_open
    "data": self.geonotebook.get_protocol()
  File "/usr/lib/python3.4/site-packages/ipykernel/comm/comm.py", line 121, in send
    data=data, metadata=metadata, buffers=buffers,
  File "/usr/lib/python3.4/site-packages/ipykernel/comm/comm.py", line 65, in _publish_msg
    content = json_clean(dict(data=data, comm_id=self.comm_id, **keys))
  File "/usr/lib/python3.4/site-packages/ipykernel/jsonutil.py", line 167, in json_clean
    out[unicode_type(k)] = json_clean(v)
  File "/usr/lib/python3.4/site-packages/ipykernel/jsonutil.py", line 167, in json_clean
    out[unicode_type(k)] = json_clean(v)
  File "/usr/lib/python3.4/site-packages/ipykernel/jsonutil.py", line 173, in json_clean
    raise ValueError("Can't clean for JSON: %r" % obj)
ValueError: Can't clean for JSON: dict_values([{'optional': [], 'required': [{'default': False, 'key': 'ann_type'}, {'default': False, 'key': 'coords'}, {'default': False, 'key': 'meta'}], 'procedure': 'add_annotation_from_client'}, {'optional': [], 'required': [{'default': False, 'key': 'x'}, {'default': False, 'key': 'y'}, {'default': False, 'key': 'z'}], 'procedure': 'set_center'}, {'optional': [], 'required': [], 'procedure': 'get_protocol'}, {'optional': [], 'required': [], 'procedure': 'get_map_state'}])

I am willing to make any changes that might be requested/required.

[minrk]

Thanks! I left a comment about how to test for dict_values.

How did you come across this? It's likely that hitting this means that code elsewhere should change, because dict_values views probably shouldn't be passed to messages at this level.

[minrk]

dict_values can be checked for with:

if PY3:
    from collections.abc import MappingView

...

if PY3 and isinstance(obj, MappingView):
    obj = list(obj)

and this should be at the top level, not inside the dict case.

[jamesmcclain]

How did you come across this? It's likely that hitting this means that code elsewhere should change, because dict_values views probably shouldn't be passed to messages at this level.

I am currently trying to get GeoNotebook running on Python 3; I encountered it there. If there is something that I can do to help detect similar issues I am happy to do so (but as you no-doubt observed, my Python skills are a bit limited).

[jamesmcclain]

I have attempted to update according to your comment, I hope that I interpreted it correctly.

[jamesmcclain]

Should I close this PR?

[Carreau]

Sorry it fell under our radar. Appologies, we'll re-have a look.

[jamesmcclain]

Ah, okay, many thanks.