Django ManyToManyField between 2 objects that point to one another

user_9899112 0
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In my project, I have 2 models with a ManyToMany field that point to each other. In this case, I have Elections and Candidates. The idea is that an Election can have multiple Candidates and that a Candidate can also be part of multiple elections (One 'Candidate' is only one person).

I have the following:

project/elections/models.py

from candidates.models import Candidate

class Election(models.Model):
    candidates = models.ManyToManyField(Candidate)
    ...

project/candidates/models.py

from elections.models import Election
    elections = models.ManyToManyField(Election)
    ...

When I try to run any command (makemigrations, runserver, etc.) I get a circular dependency between Election and Candidate which crashes. I have the models in different apps as a coding practice.

Should I:

  1. Move both models to one app and one file

  2. Not have the models pointing to each other (how would I then accomplish my goal?)

  3. Do something different

python-3.x django-models django python
2 Answers

You do not need to do this. A many-to-many field is already bidirectional. Just define it on one side, and use the reverse relation.

user_1043490

To avoid circular dependency don't import the models, use strings instead, and include the applications name as namespace

project/elections/models.py

class Election(models.Model):
    candidates = models.ManyToManyField('candidates.Candidate')

Update

As the django docs points out, you only need to declare the relation on one of the models https://docs.djangoproject.com/es/2.1/topics/db/models/#many-to-many-relationships

It doesn’t matter which model has the ManyToManyField, but you should only put it in one of the models – not both.

user_72643410
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