如何在 django rest 框架中使用外键进行计数

Question

这是我的models.pyclass Language(models.Model):    language_id     = models.BigAutoField(primary_key=True)    language_name   = models.CharField(max_length=255)    created_on      = models.DateTimeField(auto_now=True)    latest_build_on = models.DateTimeField(auto_now_add=True)    latest_version  = models.DecimalField(max_digits=5, decimal_places=2)    company         = models.OneToOneField('Company',on_delete=models.CASCADE,related_name='language')    def __str__(self):        return self.language_nameclass Frameworks(models.Model):    framework_id    = models.BigAutoField(primary_key=True)    framework_name  = models.CharField(max_length=255)    framework_logo  = models.FileField()    created_on      = models.DateTimeField(auto_now=True)    latest_build_on = models.DateTimeField(auto_now_add=True)    latest_version  = models.DecimalField(max_digits=5, decimal_places=2)    language        = models.ForeignKey('Language',on_delete=models.CASCADE,related_name='frameworks')    def __str__(self):        return self.framework_nameclass Technologies(models.Model):    technology_id   = models.BigAutoField(primary_key=True)    technology_name = models.CharField(max_length=255)    description     = models.TextField()    language        = models.ManyToManyField('Language',related_name='technology')    def __str__(self):         return self.technology_name这是 serializers.pyclass GetLanguageSerializer(serializers.ModelSerializer):    technology = serializers.StringRelatedField(many=True)    frameworks = serializers.StringRelatedField(many=True)    class Meta:        model = Language        fields = ('language_name','created_on','latest_build_on','latest_version','company','technology','frameworks')        depth = 1class LanguageSerializer(serializers.ModelSerializer):    class Meta:        model = Language        fields = ('language_name','created_on','latest_build_on','latest_version','company')

Answer 1

SerializerMethodField()在您的序列化程序中使用

class GetLanguageSerializer(serializers.ModelSerializer):

    technology = serializers.StringRelatedField(many=True)

    frameworks = serializers.StringRelatedField(many=True)

    total_technology = serializers.SerializerMethodField(read_only=True)

    toatl_frameworks = serializers.SerializerMethodField(read_only=True)

    def get_toatl_frameworks(self, language):

        return language.frameworks.count()

    def get_total_technology(self, language):

        return language.technology.count() # change 'technology' with corresponding "related_name" value

    class Meta:

        model = Language

        fields = (other_fileds, 'total_technology', 'toatl_frameworks')

        depth = 1