added type extension for int64 format support

[archandha]

Hi,
for a current project I need to be able to explicitly declare an integer value with format int64. As I didn't find a workaround, I did a minimal code extension to drf-spectacular to provide this.

I currently use this with such sample code:

class BigIntegerFieldFix(OpenApiSerializerFieldExtension):
    """fix serializer field BigIntegerField beeing reported as type integer, format int64 by spectacular"""
    target_class = 'restapi.serializers.BigIntegerField'

    def map_serializer_field(self, auto_schema, direction):
        return build_basic_type(OpenApiTypes.INT64)


class BigIntegerField(serializers.IntegerField):
    """dummy serializer field implementation to have spectacular make this type integer, format int64 in schema"""
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

in my drf serializers. Maybe, this is somewhat usefull for others, too.

[tfranzel]

hi @archandha, thank you it makes perfect sense. i noticed there are a few others missing. gonna add then too