model_form Forms return '' instead of None for empty fields. about flask-mongoengine

[anemitz]

Seems like this is due to the StringField implementation in wtforms which EmailField is based.

https://bitbucket.org/simplecodes/wtforms/src/a5f9e30260cc/wtforms/fields/core.py#cl-466

Wouldn't the same check need to be made in your application whether email was '' or None=> if user.email vs if user.email == None?

[lucasvo]

@anemitz I'm not entirely sure what you're referencing to now. The problem is, that the way the mongorest emailfield is implemented is, that it will raise a validation error if it's passed in an empty string.

I don't have an issue with it passing back '' however mongonengine does. The testcase doesn't show the entire problem. The whole point of model_form(SomeDocument) is that I can then do something like: SomeDocument(form.data) and if the form validated, the document should also validate. Which it does not, because email='' is invalid.

[lucasvo]

@anemitz I comitted a fix: e55bf96

[thomasst]

This is correct behavior. email is supposed to be an empty string instead of None. Otherwise things will break, e.g. Optional validation will no longer work properly.

[lucasvo]

@thomasst merged the pull request. Though the same issue might come up for other field types.

[mapio]

Unfortunately the fix seems not to work with flask-admin where "None" appears as the default string value in email fields (when creating new records); moreover, even if you remove the default vaule by hand, the validation fails when model save is attempted.

[mapio]

from flask import Flask

from flask.ext import admin
from flask.ext.admin.contrib.mongoengine import ModelView
from flask.ext.mongoengine import MongoEngine

db = MongoEngine()

class TestDocument( db.Document ):
    email = db.EmailField( required = False )

app = Flask( __name__ )
app.config[ 'SECRET_KEY' ] = '123456790'
app.config['MONGODB_SETTINGS'] = {'DB': 'testing'}

db.init_app( app )
adm = admin.Admin( app, 'TestCase' )
adm.add_view( ModelView( TestDocument ) )

if __name__ == '__main__':
    app.run()

[mapio]

[mapio]

[mapio]

Observe that in the first screenshot is the model validation that fails during save (after I submitted a form with empty email – the "None" you see has been re-added with the flashed message), while in the second example is the form validation that fails (because the field contains a wrong "default" value).

[rozza]

Please open a new ticket @mapio and ill fix for 0.7

[mapio]

Thank you @rozza, I just added issue #44.