Newer constraint declarations and Foreign Keys

[dans...@gmail.com]

Hi guys,

I remember that there is a new way to declare constraints in class Meta on a model, and that this is preferable for unique_together constraints.

I've long wanted a way with Django to have database foreign key constraints cascade in the database rather than via Django.   Is there now a way to do this?

Thanks!

[Adam Johnson]

No, there is not currently a way in Django to declare such constraints. You can always create them in a migration using the RawSQL operation, then rely on them in your code.

This blog post relates to custom relationships which would allow you to model them, I think: https://schinckel.net/2021/07/14/django-implied-relationship/

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[charettes]

If you're interested in following the development of the database level foreign key constraints feature you should CC to #21961 [0]

The latest attempt at implementing them was recently closed due to inactivity [1]

Cheers,

Simon

[0] https://code.djangoproject.com/ticket/21961

[1] https://github.com/django/django/pull/14550

[st...@jigsawtech.co.uk]

I'm part of the way working through a solution for this for MySQL. I just need to finish off the tests and documentation then it will be up on GitHub I just had to put it on hold but it fixes an issue in MySQL 5.7+ for Django that otherwise occurs if the database you are using is used by anything outside of Django that may need to perform deletes