django select related not giving expected result-CodePudding

I am querying select related between two models Requirements and Badge Requirement has a related badge indicated by badge_id Models are,

        
        
        class Badge(models.Model):
            level = models.PositiveIntegerField(blank=False, unique=True)
            name = models.CharField(max_length=255, blank=False , unique=True)
            description = models.TextField(blank=True)
        
            class Meta:
                verbose_name = _("Badge")
                verbose_name_plural = _("Badges")
        
            def __str__(self):
                return self.name
        
            def get_absolute_url(self):
                return reverse("Badge_detail", kwargs={"pk": self.pk})
    
    
    """ Requirement Model for requirements """
    
    
    class Requirement(models.Model):
        number = models.PositiveIntegerField(blank=False)
        badge = models.ForeignKey(Badge, on_delete=models.CASCADE)
        name = models.CharField(max_length=255)
        description = models.TextField(blank=True)
    
        class Meta:
            verbose_name = _("Requirement")
            verbose_name_plural = _("Requirements")
    
        def __str__(self):
            return self.name
    
        def get_absolute_url(self):
            return reverse("Requirement_detail", kwargs={"pk": self.pk})

In My view I try to join both tables and retrieve. It is,

""" ajax requirements in requirements table """


def get_requirements(request):

    requirements = Requirement.objects.all().select_related('badge').values()
    print(requirements)
    return JsonResponse(list(requirements), safe=False)

The result is, to the frontend,

to the backend,

Why does it not give me both tables' values?

CodePudding user response：

Best way to achieve that is using Serializers which are the key component to deal with transforming data from models to JSON and the inverse:

To use this approach you can create the following serializers: yourapp.serializers.py

from rest_framework.serializers import ModelSerializer
from yourapp.models import Requirement, Badge


class BadgeSerializer(ModelSerializer):
    class Meta:
        model = Badge
        fields = '__all__'

class RequirementSerializer(ModelSerializer):
    badge = BadgeSerializer()

    class Meta:
        model = Requirement
        fields = '__all__'

After that you should go to your views.py file and do the following changes:

from yourapp.serializers import RequirementSerializer


def get_requirements(request):
    reqs = Requirement.objects.select_related('badge')
    return JsonResponse(RequirementSerializer(reqs, many=True), safe=False)

In this way you will have a more flexible way to add or remove fields from the serializer, and your application is also going to be more decoupled and easy to maintain.