Nested validation in Django Rest Framework

问题

Using django rest framework I want to validate fields.

Correct input request:

{
   test_field_a: {test_field_c: 25}, 
   test_field_b: {}
}

My serializers.py (I don't have any associated models and the models.py itself):

from rest_framework import serializers
class TestSerializer(serializers.Serializer):
  test_field_a = serializers.JSONField(label='test_field_a', allow_null=False, required=True)
  test_field_b = serializers.JSONField(label='test_field_b', required=True)
  test_field_c = serializers.IntegerField(label='test_field_c)

Wrong input request (which should state that int field is required) :

{
   test_field_a: {test_field_c: 'wrong'}, 
   test_field_b: {}
}

Now test_field_a and test_field_b are validated as required. But how to make validation of fields on different levels of the request? (in this case test_field_c)

回答1:

JSONField just checks that a field contains correct JSON structure. You need to do it plus check values from this JSON.

There are several ways to do it:

You can write your own custom field type (it's nice if you are planning to do something similar in other serializers);

You can change field validation (try something like this):

from rest_framework import serializers

class TestSerializer(serializers.Serializer)::
    test_field_a = serializers.JSONField(label='test_field_a', allow_null=False, required=True)
    test_field_b = serializers.JSONField(label='test_field_b', required=True)

    def validate_test_field_a(self, value):
        """
        Check that test_field_a .
        """
        if not isinstance(value.get('test_field_c'), int):
           raise serializers.ValidationError("Some error message")
       return value

You can try nested validation:

from rest_framework import serializers


class Test1Serializer(serializers.Serializer):
    test_field_c = serializers.IntegerField(label='test_field_c')


class TestSerializer(serializers.Serializer):
    test_field_a = Test1Serializer()
    test_field_b = serializers.JSONField(label='test_field_b', required=True)

回答2:

The serializer's JSONField does not have a validation for nested fields because it is not meant to nest explicitly declared fields and as far as I know, there is currently no way to specify a json schema to validate it. What you can do is validate the field yourself by declaring a validate_test_field_a validation method.

For example:

    def validate_test_field_a(self, value):
        if 'test_field_c' not in value:
            raise serializers.ValidationError('`test_field_c` is required')
        return value

Generally, if you find yourself needing to validate the nested type inside the JSONField, then it is a sign of bad architecture and you should consider using nested serializers instead. Same applies to using JSONField in the model

来源：https://stackoverflow.com/questions/53651167/nested-validation-in-django-rest-framework

标签

python

django

validation

django-rest-framework