Usage - Making tags on a per user basis

[CarloCogni]

Hi,

in my project there is a user case where I need to make the tags associated with the user. This way every user can create their own set of tags, also when I present a page with all tags I could to something like Tag.objects.filter(user=request.user)

I've asked a question on StackOverflow, but I'm thinking I could be useful to ask you directly.
https://stackoverflow.com/questions/72823187/django-how-to-make-tags-on-a-per-user-basis.

Let me know if I can provide with more informations.

Thank you very much.

Cheers

Carlo

[chambersh1129]

Try using the TaggedItem instead of Tag for your query, it has a class method that returns a queryset of Tags for the object provided. Something like this should do it:

from taggit.models import TaggedItem

tags = TaggedItem.tags_for(request.user)

[rtpg]

@CarloCogni Basically you're most of the way there, just call MyTag.objects.filter(user=request.user) as a default queryset in various places. This does mean that when you set or add tags you'll need to pass in the right tag_kwargs.

from the django-taggit test code:

        apple = OfficialFood.objects.create(name="apple")

        # let's add two official tags
        apple.tags.add("foo", "bar", tag_kwargs={"official": True})

        # and two unofficial ones
        apple.tags.add("baz", "wow", tag_kwargs={"official": False})

here our custom tag model has an extra official boolean, in your case it's user. You'll just need to do stuff like this (or outright create custom models. You don't have to use our helpers!)

[rtpg]

Would be good to add this to the FAQ, as multitenant keys is a super common thing that people need to deal with.

[ethagnawl]

Apologies for potentially hijacking this thread but I'm confused about the example referenced above and how it applies to OP's question. If two users attempted to use the same tags, wouldn't that result in a uniqueness validation error? Is this the sort of situation you were considering when suggesting the end user create their own models, @rtpg?

For example:

user_1_apple.tags.add("foo", tag_kwargs={"user_id": 1})
user_2_apple.tags.add("foo", tag_kwargs={"user_id": 2})

If I modify the taggit test case referenced above in accordance with my example, the test fails with:

django.db.utils.IntegrityError: UNIQUE constraint failed: tests_officialtag.name

If a custom model was used and the uniqueness constraint was a compound one across name and user_id, would that just work with the surrounding taggit machinery?

[rtpg]

@ethagnawl thanks for the question, it does feel like we should document a full flow for this

I think there are multiple ways to do this, here is a way that I handled this a while back:

from taggit.models import TaggableManager, GenericTaggedItemBase


class MyTag(models.Model):
    user = models.ForeignKey(...)
    name = models.CharField(....)

class MyTaggedItem(GenericTaggedItemBase):
    tag = models.ForeignKey(MyTag, ...)


class MyResource(models.Model):
    # this allows me to put tags on the resource
    tags = TaggableManager(blank=True, through=MyTaggedItem)

The core point here is that I set up a tagged item model, but provide my own tag class entirely (thus being able to set my unique constraints myself instead of using the ones set in taggit.models.Tag). Then MyResource can use the tags.

There might be a way to subclass Tag itself for MyTag in this (you could replace name yourself? Or otherwise changeup the uniqueness constraint), but this is all very much a "make sure to write tests" thing.

[ethagnawl]

Thanks for following up, @rtpg!

That's pretty close to what I started sketching out yesterday after asking my question above. So far, so good but you're spot on about needing to lean on tests. I'm happy to potentially help with documentation once I'm satisfied with my solution.