Meta passed to FlaskForm init may be None

[virlos]

The definition of Form at http://wtforms.readthedocs.io/en/latest/forms.html#wtforms.form.Form.__init__ has meta=None, which should be preserved by subclasses.

Since 0.14, Flask-WTF assumes that meta is a dict if present in kwargs. This breaks wtforms-json, which preserve the WTForms default.

See also kvesteri/wtforms-json#47.

[virlos]

Since I got an email requesting for an example, here is one:

$ cat example.py 
from flask import Flask
from flask_wtf import FlaskForm
from wtforms import StringField
import wtforms_json


class ExampleForm(FlaskForm):

    example = StringField()


wtforms_json.init()
app = Flask('example')

with app.test_request_context('/'):
    myjson = {'example': 'passed'}
    goodform = ExampleForm.from_json(myjson, meta={}, csrf_enabled=False)
    print 'Goodform', goodform.example.data
    badform = ExampleForm.from_json(myjson, csrf_enabled=False)
$ python example.py 
Goodform passed
Traceback (most recent call last):
  File "example.py", line 19, in <module>
    badform = ExampleForm.from_json(myjson, csrf_enabled=False)
  File "/usr/local/lib/python2.7/dist-packages/wtforms_json/__init__.py", line 233, in from_json
    **kwargs
  File "/usr/local/lib/python2.7/dist-packages/wtforms/form.py", line 212, in __call__
    return type.__call__(cls, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/flask_wtf/form.py", line 85, in __init__
    kwargs.setdefault('meta', {}).setdefault('csrf', csrf_enabled)
AttributeError: 'NoneType' object has no attribute 'setdefault'

[davidism]

Thanks, I dug through it in the mean time and figured out what you were referring to.

[davidism]

Fixed in release 0.14.2 on PyPI.