CODEWITHSUNDEEP
pythondjangodjango-orm
Xar
Xar

Reputation: 7910

Django ORM: Annotate the Value of matching object

I've been using Django's ORM annotate before with success for a few times, but I'm having trouble with this especific case.

I want to annotate a new field, called tag_to_show, when the value of the field my_tag matches a certain regular expression.

This is what I have for the moment:

queryset.annotate(tag_to_show=Case(When(my_tag__iregex=pattern,
                                         then=Value("I don't know what to put here")),
                                    output_field=CharField(),
                                    default=Value("Not matched")))

I'm just applying a regular expression to the my_tag field. If the regex matches the string contained in the my_tag field of a certain object, I want to annotate its value in a new field called tag_to_show.

Any ideas what to put inside de Value parameter?

Upvotes: 0

Views: 2431

Answers (2)

AKS
AKS

Reputation: 19831

I think what you want is the F() expression:

queryset.annotate(tag_to_show=Case(
                      When(my_tag__iregex=pattern, then=F('my_tag')),
                      output_field=CharField(), 
                      default=Value("Not matched")))

Upvotes: 2

albar
albar

Reputation: 3100

I think the answer is:

queryset.annotate(tag_to_show=Case(When(my_tag__iregex=pattern,
               then='my_tag'),
               output_field=CharField(),
               default=Value("Not matched")))

Upvotes: 0

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