Django序列化正反向查询

序列化正反向查询（serializers.Serializer）

models.py

class CourseType(Base):
    title = models.CharField('课程类别', max_length=16)
    sequence = models.IntegerField('展示顺序', default=10)

    class Meta:
        db_table = 'tb_course_type'

    def __str__(self):
        return self.title


class CourseTag(Base):
    title = models.CharField('课程标签', max_length=16)
    sequence = models.IntegerField('展示顺序', default=10)

    class Meta:
        db_table = 'tb_course_tag'

    def __str__(self):
        return self.title

    
class Course(Base):
    STATUS = (
        ('0', '即将上线'),
        ('1', '已上线'),
        ('2', '已下线'),
    )

    title = models.CharField('课程名', max_length=24)
    desc = models.CharField('课程描述', max_length=256)
    img = models.ImageField('课程logo', upload_to='course', null=True)
    course_type = models.ForeignKey(CourseType, verbose_name='课程类型', on_delete=models.SET_NULL, default=None, null=True)
    course_tag = models.ManyToManyField(CourseTag, verbose_name='课程标签')
    status = models.CharField('课程状态', choices=STATUS, max_length=8, default='1')
    attention = models.IntegerField('关注人数', default=0)
    learner = models.IntegerField('学习人数', default=0)

    class Meta:
        db_table = 'tb_course'

    def __str__(self):
        return self.title

1. 正向查找

serializer.py

class CourseSerializer(serializers.ModelSerializer):
    course_type = serializers.CharField(source='course_type.title')
    # 正向查找，显示一对多字段名称

    class Meta:
        model = Course
        fields = '__all__'
        
        
class CourseTypeSerializer(serializers.ModelSerializer):
    class Meta:
        model = CourseType
        fields = '__all__'

1.1 未使用正向显示效果

1.2 使用正向显示效果

2. 反向查找

serializer.py

class CourseSerializer(serializers.ModelSerializer):
    course_type = serializers.CharField(source='course_type.title')

    class Meta:
        model = Course
        fields = '__all__'


class CourseTypeSerializer(serializers.ModelSerializer):
    # 一对多关联对象序列化
    # Course().course_set  必须用.后面的xxx作为字段名,也就是小写类名_set
    # 一个类型对应多个课程，一对多反向查询type包含的哪些course

    course_set = CourseSerializer(many=True)
    # 方法1：使用关联对象的序列化器

    # course_set = serializers.PrimaryKeyRelatedField(read_only=True, many=True)
    # 方法2：此字段将被序列化为关联对象的主键

    # course_set = serializers.StringRelatedField(read_only=True, many=True)
    # 方法3：此字段将被序列化为关联对象的字符串表示方式（即__str__方法的返回值）

    class Meta:
        model = CourseType
        fields = '__all__'