Unique over the three values

[chrko]

In my current project I have the problem that I want the unique index over the three columns (from_, to, field.sort_value_field_name) in generated through model which is currently specified fix: 53322c4a[…]/sortedm2m/fields.py#L74

What should I do in this case?

Should be there an option three_column_unique?

[gregmuellegger]

I pushed something in the branch feature/customizable-intermediate-model. It
pulls the creation of the through model into the Field class and provides a
hook in the form of get_intermediate_model_attributes. I think it should
be possible with this hook to implement your custom unique_together with
something like this:

class MySortedM2M(SortedManyToManyField):
    def get_intermediate_model_attributes(self, attrs):
        attrs['Meta'].unique_together = (
            (attrs['_sort_field_name'], attrs['_to_field_name'], attrs['_from_field_name'],),
        )
        return attrs

Then use your custom field their and it should work well then.
Please give that a try and report back if that works for you. I'm happy to
merge these changes into master once you confirm that it solves your usecase.

[chrko]

Currently feature/customizable-intermediate-model is even with master?

[gregmuellegger]

Oops, I didn't push. Sorry! Should be there now.

[chrko]

Yes, this works. Thanks!

[gregmuellegger]

I did a new refactor of the model creation. So the example from above won't work any more as it had with the branch. However you can now hook into the get_intermediate_model_meta_class() method to accomplish your usecase.

I'm curious what you think of the refactor in a66b9ac

[chrko]

I like the way to intercept the creation of the through model with hooks as of overiding some small methods.
And if you have now forgotten any corner case, the first step is done. 👍