Proposal for getting help_text from model fields

[jter]

It would be great that filters of FilterSet could get help_text from fields of Models. This feature can save some repetitive work when we need help_text for auto-generated docs from model fields without redefining the filters in FilterSet. Could this proposal be a good idea?

[rpkilby]

Hi @jter. I feel like this has been talked about before, but I can't find the relevant discussion. In short, this suggestion works well for FilterSets like...

class UserFilter(FilterSet):
    class Meta:
        model = User
        fields = ['username', 'email', 'name', ...]

Adding the help_text is reasonable in this case, since the filter's data type matches the data type of the underlying model field. eg /api/users?username=jter

However, Meta.fields can also be used like so:

class ArticleFilter(FilterSet):
    class Meta:
        model = Article
        fields = {
            'author': ['exact', 'startswith', 'endswith', ...],
            'title': ['exact', 'startswith', 'endswith', ...],
            'published_at': ['exact', 'isnull'],
        }

In this case, adding in the model's help_texts is a little less useful.

1. There may be several filters for the same model field, making the help_text repetitive/redundant.
2. The data type of the filter doesn't necessarily match the data type of the model field. eg, information on entering a datetime may not be appropriate for an isnull lookup where the input is a boolean.

---

This would be fairly straightforward to achieve with a custom FilterSet base class:

class HelpfulFilterSet(django_filters.FilterSet):
    @classmethod
    def filter_for_field(cls, f, name, lookup_expr):
        filter = super(HelpfulFilterSet, cls).filter_for_field(f, name, lookup_expr)
        filter.extra['help_text'] = f.help_text
        return filter

[jter]

Thank you for your illustrating, clear and useful.
@rpkilby