TypeError: string indices must be integers with pandoc 2.10.1

[Matthew Lloyd]

I'm hitting an incompatibility between this library and pandoc 2.10.1 when parsing a simple table with a single row and cell, see the error below.

$ pandoc --version
pandoc 2.10.1
Compiled with pandoc-types 1.21, texmath 0.12.0.2, skylighting 0.8.5
Copyright (C) 2006-2020 John MacFarlane
Web:  https://pandoc.org
This is free software; see the source for copying conditions.
There is no warranty, not even for merchantability or fitness
for a particular purpose.

$ python3
Python 3.8.2 (default, Jul 16 2020, 14:00:26)
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pandoc
>>> pandoc.read('<table><tr><td></td></tr></table>', format='html')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/.local/lib/python3.8/site-packages/pandoc/__init__.py", line 311, in read
    return read_json_v2(json_)
  File "/home/.local/lib/python3.8/site-packages/pandoc/__init__.py", line 634, in read_json_v2
    blocks = read_json_v2(json_["blocks"], ["list", ["Block"]])
  File "/home/.local/lib/python3.8/site-packages/pandoc/__init__.py", line 588, in read_json_v2
    return [read_json_v2(item, item_type) for item in json_]
  File "/home/.local/lib/python3.8/site-packages/pandoc/__init__.py", line 588, in <listcomp>
    return [read_json_v2(item, item_type) for item in json_]
  File "/home/.local/lib/python3.8/site-packages/pandoc/__init__.py", line 663, in read_json_v2
    args = [read_json_v2(jarg, t) for jarg, t in zip(json_args, constructor[1][1])]
  File "/home/.local/lib/python3.8/site-packages/pandoc/__init__.py", line 663, in <listcomp>
    args = [read_json_v2(jarg, t) for jarg, t in zip(json_args, constructor[1][1])]
  File "/home/.local/lib/python3.8/site-packages/pandoc/__init__.py", line 663, in read_json_v2
    args = [read_json_v2(jarg, t) for jarg, t in zip(json_args, constructor[1][1])]
  File "/home/.local/lib/python3.8/site-packages/pandoc/__init__.py", line 663, in <listcomp>
    args = [read_json_v2(jarg, t) for jarg, t in zip(json_args, constructor[1][1])]
  File "/home/.local/lib/python3.8/site-packages/pandoc/__init__.py", line 608, in read_json_v2
    return read_json_v2(json_, value_type)
  File "/home/.local/lib/python3.8/site-packages/pandoc/__init__.py", line 585, in read_json_v2
    return read_json_v2(json_, type_)
  File "/home/.local/lib/python3.8/site-packages/pandoc/__init__.py", line 588, in read_json_v2
    return [read_json_v2(item, item_type) for item in json_]
  File "/home/.local/lib/python3.8/site-packages/pandoc/__init__.py", line 588, in <listcomp>
    return [read_json_v2(item, item_type) for item in json_]
  File "/home/.local/lib/python3.8/site-packages/pandoc/__init__.py", line 619, in read_json_v2
    constructor = getattr(types, json_["t"])._def
TypeError: string indices must be integers

[Sébastien Boisgérault]

Yes, you're right, sorry for this. At this stage I do not properly support the recent versions of pandoc (and pandoc-types).

The why : the json serialization of the recents versions of pandoc (the original Haskell program) are not as consistent at the moment as they used to be. So at this stage I cannot (automatically, from the info available in the pandoc types hierarchy) correctly read or write json data for pandoc.

I have reported this issue upstream jgm/pandoc-types#75 and I hope that it will be sorted out. In the meantime, I should get the unsupported versions out of the supported list, so that at least you have a decent (and early) error message.

Thanks for the issue !

[Sébastien Boisgérault]

@matthewlloyd

I have rollbacked support for pandoc 2.10.x for the moment. If you try again, you should get:

>>> import pandoc
>>> pandoc.read("Hello, world!")
Traceback (most recent call last):
...
ValueError: pandoc 2.10.1 is not registered

[Matthew Lloyd]

Many thanks for the information, and for the great Python package. I'll downgrade my pandoc and carry on as normal until the upstream repo sorts out the type incongruity.

[Sébastien Boisgérault]

The 2.10.x versions of pandoc are still not supported (for the reasons explained in jgm/pandoc-types#75), but the more recent versions (2.11.4 being the latest at the moment) should be fine. Otherwise, it's a bug !