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Python

Posted by Amber Diehl
Amber Diehl
15,402 Points

Change in foreign key for SocialNetwork project

Kenneth Love thought you might want to know that there appears to be another change you might want to note for your Flask social network project.

I had this for the Post model, as shown in the video:

    user = ForeignKeyField(
        rel_model=User,
        related_name='posts'
    )

I was getting an error regarding wrong number of parms being passed for init. After doing some research, it appears the syntax has changed. I modified my model to this:

    user = ForeignKeyField(User,
        related_name='posts'
    )

And the error disappeared and all was well.

2 Answers

Jeff Muday
MOD
Jeff Muday
Treehouse Moderator 28,732 Points
Jeff Muday
Jeff Muday
Treehouse Moderator 28,732 Points

Peewee changed versions (currently at 3.0.x) since Kenneth Love recorded the video. I am not sure what version workspaces are tethered to. Workspaces "baked in" the Peewee library, so you can't check it with "pip freeze" like I do on my own development environment.

I dug into the source code--

https://github.com/coleifer/peewee/blob/master/peewee.py

In the source code, you can see what he slipped in there...

deprecated('"rel_model" has been deprecated in favor of ' '"model" for ForeignKeyField objects.')

also note:

deprecated('"related_name" has been deprecated in favor of ' '"backref" for Field objects.')

Note the dunder-init method. The first REQUIRED parameter after self, is model. So Peewee is going to complain if you use rel_model as the first parameter.

I recently corresponded with the author of Peewee, Charles Leifer to call his attention to another issue I discovered with Flask-Admin-- it wasn't a bug, but related to the version change. Some of the changes were to make Peewee naming and API more consistent with other ORMs. Charles is very talented and very helpful.

See below:

class ForeignKeyField(Field):
    accessor_class = ForeignKeyAccessor

    def __init__(self, model, field=None, backref=None, on_delete=None,
                 on_update=None, _deferred=None, rel_model=None, to_field=None,
                 object_id_name=None, related_name=None, *args, **kwargs):
        super(ForeignKeyField, self).__init__(*args, **kwargs)
        if rel_model is not None:
            __deprecated__('"rel_model" has been deprecated in favor of '
                           '"model" for ForeignKeyField objects.')
            model = rel_model
        if to_field is not None:
            __deprecated__('"to_field" has been deprecated in favor of '
                           '"field" for ForeignKeyField objects.')
            field = to_field
        if related_name is not None:
            __deprecated__('"related_name" has been deprecated in favor of '
                           '"backref" for Field objects.')
            backref = related_name

        self.rel_model = model
        self.rel_field = field
        self.declared_backref = backref
        self.backref = None
        self.on_delete = on_delete
        self.on_update = on_update
        self.deferred = _deferred
        self.object_id_name = object_id_name
Amber Diehl
Amber Diehl
15,402 Points
Amber Diehl
Amber Diehl
15,402 Points

Jeff Muday thanks for your detailed reply!

I neglected to say that I was not using workspaces when following this course. But thought it still worth noting since his teacher notes included other changes (e.g. authenticated being changed from method to property).