CODEWITHSUNDEEP
pythondjango
Parry
Parry

Reputation: 187

How to use a model in a Python Django project for multiple applications?

I have a Django project called myoffice. In this project I created an app proposals. Before creating this I had performed makemigrations and migrate creating auth_user table and other tables like auth_user_groups etc.

After creating proposals app, it was working fine.

Now I created a new app called expenses. I have written all models, views, templates and url files. In my models, a couple of models have foreign key reference to users like this:

exch_usr = models.ForeignKey('User', on_delete=models.PROTECT)

I have imported user model as below:

from django.contrib.auth.models import User

Yet, I am getting an error while running makemigrations:

ValueError: Cannot create form field for 'txn_usr' yet, because its related model 'User' has not been loaded yet

Upvotes: 0

Views: 142

Answers (3)

Reidel
Reidel

Reputation: 377

The @danielr 's answer is perfect but I have a recommendation for you @Parry. So if the User model might be swapped out for another(thinking in the future) and to make your application as reusable as possible you should use the settings.AUTH_USER_MODEL as a references in your models . More information on customizing and referencing the User model can be found at https://docs.djangoproject.com/en/1.10/topics/auth/customizing/#referencing-the-user-model. And inside your code you must use the get_user_model Django(to create User references ) utility to create this switch in a clean way.

class SomeClass(models.Model): .... custome_user = models.ForeignKey(settings.AUTH_USER_MODEL)

and to make references to User properties:

from django.contrib.auth import get_user_model User = get_user_model() class AnotherClass(models.Model): .... username = User.USERNAME_FIELD

Upvotes: 0

tell k
tell k

Reputation: 615

If you are already importing User model on that models.py, you can just set it to ForeignKey. be aware that it's not a string.

exch_usr = models.ForeignKey(User, on_delete=models.PROTECT)

Upvotes: 0

Daniel Roseman
Daniel Roseman

Reputation: 599610

If the linked model is in another app, you need to refer to that in the destination string.

exch_usr = models.ForeignKey('auth.User', on_delete=models.PROTECT)

Note, you do not need to import User at all.

Upvotes: 1

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