How to concating two field with in django queryset?

Hy there, Concating two field raise TypeError: select_format() missing 1 required positional argument: 'params'

Here is my model

from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation

class Report(models.Model):
     content_type = models.ForeignKey(ContentType, verbose_name=_('content_type'),
                                     related_name="content_type_set_for_%(class)s",
                                     on_delete=models.CASCADE)
    object_id = models.PositiveIntegerField()
    content_object = GenericForeignKey(ct_field="content_type", fk_field="object_id") 

and here is my query in views.py

from django.db.models import CharField,F,ExpressionWrapper
from .models import Report

queryset=Report.objects.annotate(combined_field=ExpressionWrapper(F('content_type')+F('object_id),
         output_field=CharField)
queryset.values(combined_field)

when i call queryset.values(combined_field) it raise "TypeError: select_format() missing 1 required positional argument: 'params' "

Can you guys help me to overcome this problem. Thanks

Back to Top