python - AttributeError at / 'Product' object has no attribute 'get_category_display'

Question

hi I want in my products api show the name of category instead of showing category id . I wrote a function to do that for me but I have this error:

 AttributeError at /
'Product' object has no attribute 'get_category_display'

how do i can fix it?? there is my serializer and category and product models

serializers:

class ProductSerializer(serializers.ModelSerializer):
    comments = serializers.SerializerMethodField()
    category = serializers.SerializerMethodField()

    class Meta:
        model = Product
        fields = ['id', 'category', 'name', 'slug', 'image_1',
                  'image_2', 'image_3', 'image_4', 'image_5',
                  'description', 'attribute', 'price', 'available', 'created', 'updated',
                  'popular', 'discount', 'comments']
        lookup_field = 'slug'
        extra_kwargs = {
            'url': {'lookup_field': 'slug'}
        }

    def get_comments(self, obj):
        comments_qs = Comment.objects.filter_parents_by_object(obj).order_by('posted')
        return CommentSerializer(comments_qs, many=True).data

    def get_category(self, obj):
        return obj.get_category_display()

models:

class Category(models.Model):
    name = models.CharField(max_length=400)

    def __str__(self):
        return self.name


class Product(models.Model):
    category = models.ManyToManyField(Category, related_name='products')
    name = models.CharField(max_length=500)
    slug = models.SlugField(max_length=500, allow_unicode=True, unique=True)
    image_1 = models.ImageField(upload_to='products_pic/%Y/%m/%d/', null=True, blank=True)
   
    description = models.TextField(null=True, blank=True)
    attribute = models.JSONField(null=True, blank=True,
                                 help_text='in this format: {"key" : "value", "key2" : "value2"}')
    price = models.PositiveIntegerField()
    discount = models.PositiveIntegerField(null=True, blank=True)
    available = models.BooleanField(default=True)
    comments = GenericRelation(Comment)

    class Meta:
        ordering = ('-created',)

    def __str__(self):
        return self.name

Answer 1

Only fields with a list of choices have a get_fieldname_display, you can present the name of the object with:

def get_category(self, obj):
    return [str(c) for c in obj.category.all()]

or if the Category model has for example a .name field, you can use:

def get_category(self, obj):
    return [c.name for c in obj.category.all()]