序列化 正向查询 和反向查询

#课程标签
class CourseTag(Base):
    title = models.CharField('课程标签', max_length=32)
    sequence = models.IntegerField('展示顺序', default=10)

    class Meta:
        db_table = 'tb_coursetag'

    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('课程名', max_length=256)
    img = models.ImageField('课程logo', upload_to='course', null=True)
    course_type = models.ForeignKey(CourseType, verbose_name='课程类别', on_delete=models.CASCADE, 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

　　

正向查询

class CourseCourseSerializers(serializers.ModelSerializer):
    corse_type = serializers.CharField(source='course_type.title')
    class Meta:
        model=Course
        fields='__all__'

　反向查询

class CourseTypeSerializers(serializers.ModelSerializer):
    course_set= CourseCourseSerializers(many=True) # 表明+set
    class Meta:
        model=CourseType
        fields='__all__'