How to give validations for a PrimaryKeyRelatedField serializer

Question

How can I add validations like required=true to the primarykeyrelated serializer?

models.py

class WorkLocation(models.Model):
    city = models.CharField(max_length=255)
    latitude = models.FloatField()
    longtitude = models.FloatField()

serializers.py

class WorkLocationField(serializers.PrimaryKeyRelatedField):

    queryset = WorkLocation.objects.all()

    def to_internal_value(self, data):
        if type(data) == dict:
            location, created = WorkLocation.objects.get_or_create(**data)
            data = location.pk
        return super().to_internal_value(data)

class JobPostSerializer(serializers.ModelSerializer):

    work_location = WorkLocationField()

    class Meta:
        model = JobPost
        fields = "__all__"

A part of my data looks like:

"hourly_pay": 10,
    "yearly_pay": 120,
    "work_location": {
        "city": "kottayam",
        "latitude": 0.00001,
        "longtitude": 0.0012
    },
    "Benefit": [
        1
    ],

I need validations for the nested JSON data.

Answer 1

Judging from your JobPostSerializer , it seems like your JobPost model has a OneToOne relationship with WorkLocation .This means that your models.py looks like this:

class WorkLocation(models.Model):
    city = models.CharField(max_length=255)
    latitude = models.FloatField()
    longtitude = models.FloatField()

class JobPost(models.Model):
    work_location = models.OneToOneField(WorkLocation, on_delete=models.CASCADE)

To provide validation for work_location field on JobPostSerializer , you can create WorkLocationSerializer as follows:

class WorklocationSerializer(serializers.ModelSerializer):
    class Meta:
        model = WorkLocation
        fields = "__all__"

    # field level validation
    def validate_city(self, value):
        # value validation
        return value

    def validate(self, data):
        # data validation
        return data

class JobPostSerializer(serializers.ModelSerializer):
    class Meta:
        model = JobPost
        fields = "__all__"

    work_location = WorkLocationSerializer()

This way you can perform all of your validations inside the WorkLocationSerializer and when added as a field on another serializer the nested validation works.