CODEWITHSUNDEEP
djangodjango-rest-framework
Rajan Chauhan
Rajan Chauhan

Reputation: 1375

Serializing ManyToManyField in DjangoRestFramework

I have 2 models here Tag and Question. All i want is to serialize the Tag Model without explicitly inside the Question Serializer where Tag model is related by ManyToMany relation with Question model.

class Question(models.Model):
    question = models.TextField(blank=False, null=False)
    question_image = models.ImageField(blank=True, null=True, upload_to='question')
    opt_first = models.CharField(max_length=50, blank=False, null=False)
    opt_second = models.CharField(max_length=50, blank=False, null=False)
    opt_third = models.CharField(max_length=50, blank=False, null=False)
    opt_forth = models.CharField(max_length=50, blank=False, null=False)
    answer = models.CharField(max_length=1, choices=(('1','1'),('2','2'),('3','3'),('4','4')))
    description = models.TextField(blank=True,null=True )
    tag = models.ManyToManyField(Tag)
    created_on  = models.DateTimeField(default= timezone.now)

class Tag(models.Model):
    name = models.CharField(max_length = 50, null=False, unique=True)

And I have serializers classes for these two models

class TagSerializer(serializers.ModelSerializer):
    class Meta:
        model = Tag
        fields = ('name',)

class QuestionSerializer(serializers.ModelSerializer):
     # tag = TagSerializer(many=True)
    def to_representation(self, obj):
        rep = super(QuestionSerializer, self).to_representation(obj)
        rep['tag'] = []
        for i in obj.tag.all():
           # rep['tag'].append({'id':i.id,'name':i.name})
           # Below doesn't give JSON representation produces an error instead
           rep['tag'].append(TagSerializer(i)) 
        return rep

    class Meta:
        model = Question
        fields = ('question', 'question_image', 'opt_first', 'opt_second', 'opt_third', 'opt_forth', 'answer', 'description', 'tag')
        read_only_fields = ('created_on',)

Here on using TagSerializer in the to_repesentation method of QuestionSerializer doesn't serialize the tag object. Instead produces error
ExceptionValue : TagSerializer(<Tag: Geography>): name = CharField(max_length=50, validators=[<UniqueValidator(queryset=Tag.objects.all())>]) is not JSON serializable

Upvotes: 1

Views: 255

Answers (1)

neverwalkaloner
neverwalkaloner

Reputation: 47354

You are trying to serialize TagSerializer class. Try to change code to serialize data:

for i in obj.tag.all():
       # rep['tag'].append({'id':i.id,'name':i.name})
       # Below doesn't give JSON representation produces an error instead
       ser = TagSerializer(i)
       rep['tag'].append(ser.data)

Also I didn't get why you are override to_representation method. Try just to define tag field in QuestionSerializer:

tag = TagSerializer(read_only=True, many=True)

Upvotes: 1

Related Questions