[django-filter] Filter Data Type / Description Issues

[SorianoMarmol]

Hello, first of all, thank you for your work and effort. It’s an incredible library.

Describe the bug

I’m having two problems with filters:

1. When I define a filter as “integer,” I can’t get it to appear as an integer in the schema (it appears as "number"). Could you guide me on where I should indicate this, please? (type hinting, extend_schema_field...)

class PositiveIntegerFilter(filters.NumberFilter):
    field_class = forms.IntegerField

I’ve tried in many places but haven’t been able to achieve it.
I should note that I am applying the filter in a custom way, meaning it doesn’t apply to a specific field of an object (it's a filter for a list that has nothing to do with objects). Maybe that’s why it can’t identify the integer type through model introspection (that’s my theory).

2. If I specify my filters adding extend_schema_field(OpenApiTypes.XXX), the help_text doesn’t transfer to the description (it gets lost in the schema).
   Is this a bug? Any way to propagate the help_text to the description?

Both problems are related for me because I can’t specify the integer type with extend_schema_field since I lose the description 😆 .

Example:

    asset_currency = extend_schema_field(OpenApiTypes.STR)(filters.ModelChoiceFilter(
        help_text=_('Filter by the currency code of the asset')
    ))

Result (without description) :

                    {
                        "in": "query",
                        "name": "asset_currency",
                        "schema": {
                            "type": "string"
                        }

To Reproduce

Define a filter with help_text like this

    asset_currency = extend_schema_field(OpenApiTypes.STR)(filters.ModelChoiceFilter(
        help_text=_('Filter by the currency code of the asset')
    ))

Expected behavior

expected result (with description=help_text):

                    {
                        "in": "query",
                        "name": "asset_currency",
                        "schema": {
                            "type": "string"
                        },
                        "description": "Filter by the currency code of the asset"
                    },

Thanks in advance

[tfranzel]

Hi and thx.

So regarding point 2: This is by design as you take control of the field schema when using extend_schema_field. Mixing together the detection with the override just creates confusion. Also imagine the case where you try to remove the help_text, which would be very hard when mixing.

Regarding 1: We basically chose to route to ignore the field_class and use the estimated model field instead. If I remember correctly, we did that because the form field_class often did not provide enough information by itself and using both sources seemed quite awkward and opaque.

drf-spectacular/drf_spectacular/contrib/django_filters.py

Line 131 in cc91637

schema = build_basic_type(OpenApiTypes.NUMBER)

I can see that this is not optimal for your use-case, but we had to make some concessions here.

[keikoro]

Re: point 2 as well as e.g. #1257:

Could the reason for people bringing this up be that extend_schema_field's name is misleading? I personally would assume that something which "extends" something else adds to it rather than replace it.