Flask-admin: 1.0.9 broke uselist=False on backref

[liclac]

In 1.0.8, I could have relationships with uselist=False with no problem (it'd just look strange with how you could actually add multiple entries in the UI…), but in 1.0.9, this instead displays the same symptoms described in #376. And just like in #376, the fix is to move the uselist=False from the backref to the relationship.

[mrjoes]

Flask-Admin never supported uselist=False on a backref and there was another bug #376 which was fixed.

I'll see if it is easy to make flask-admin work with o2o backrefs too.

[nshelly]

Just curious, why was this issue was closed? We're having the same issue. Thanks.

[mrjoes]

You have to specify uselist=False on a relationship side and it'll work.

[nshelly]

Ok, we tried adding it to the relationship and it comes up with the same error, that the inline one-to-one model is not iterable.

in models.py
class User(Base):
    __tablename__ = 'users'

    id = sa.Column(sa.Integer(), primary_key=True)
    profile = relationship('Profile', backref="user", uselist=False)

class Profile(Base):
    __tablename__ = 'profiles'

    id = sa.Column(sa.Integer(), primary_key=True)
    user_id = sa.Column(sa.Integer, sa.ForeignKey("users.id"), nullable=False)


in admin page:
class UserModelView(EditOnlyModelView):
    inline_models = (Profile, )

def initialize_admin(app):
    admin = Admin(app, name='bliss', template_mode='bootstrap3')
    admin.add_view(UserModelView(User, db))

Traceback:
  File '/lib/python2.7/site-packages/flask_admin/model/fields.py", line 44, in process
    res = super(InlineFieldList, self).process(formdata, data)
  File "/lib/python2.7/site-packages/wtforms/fields/core.py", line 888, in process
    for obj_data in data:
TypeError: 'Profile' object is not iterable

[mrjoes]

That's different one - inline models can't work with one-to-one relationships, they always assume it is one-to-many relationship.

[nshelly]

Ok, thanks. Is there another way you would suggest for one-to-one relationships? It's possible to just override the call before process(formdata, data), and check if it's a list, otherwise add it to one, but this seems a bit blunt.

[mrjoes]

Goal is to edit two related models at once? Also, is there a chance that another model might not exist (your foreign keys are nullable)?

In any case, I'd use wtforms machinery to do it: http://wtforms.readthedocs.org/en/latest/fields.html#wtforms.fields.FormField

Only problem with this approach - you will have to override populate_obj in your form and create instance of related model if related model does not exists.

[nshelly]

Great thanks! Yes, that's the idea (good point, that it could be nullable). I'll take a look at using wtforms here.

[bepetersn]

@nshelly, Any update on how/if you got this to work? I'm looking at using 1-to-1 inline model as well, possibly.