Python 3.6.8
Django==2.2
djangorestframework 3.11.1

1.Models

1.1 母表

class Case():
    class Meta:
        db_table = "case"
    name = models.CharField("用例名称", null=False, max_length=100)
    ...
    apis = models.ManyToManyField(API, db_table='api_case', related_name='api_case_relate')

1.2 子表

class API(BaseTable):
    """
    API信息表
    """
    class Meta:
        db_table = "api"
   name = models.CharField("接口名称", null=False, max_length=100, db_index=True)
   ...

2.查询和序列化

2.1母表查询

# api_case 是api和case的关系表

# 使用子表的字段在关系表中查询
Case.objects.filter(apis__id=3736).all()
sql等于
SELECT case.*  FROM `case` INNER JOIN `api_case` ON (`case`.`id` = `api_case`.`case_id`) WHERE `api_case`.`api_id` = 'xxx'

# 使用目表的条件在关系表中查询
Case.objects.get(id=169).apis.all()
sql等于
SELECT api.* FROM `api` INNER JOIN `api_case` ON (`api`.`id` = `api_case`.`api_id`) WHERE `api_case`.`case_id` = 'xxx'

2.2主表序列化

class CaseSerializer(serializers.ModelSerializer):
    """
    用例信息序列化
    """
    apis = serializers.PrimaryKeyRelatedField(queryset=models.API.objects.all(), many=True)

    class Meta:
        model = models.Case
        fields = '__all__'

2.3子表查询

# api_case_relate 是 Case Model中的related_name

# 使用母表的字段查询在关系表中查询
API.objects.get(pk='xxx').api_case_relate.all()
sql等于
SELECT api.* FROM `api` INNER JOIN `api_case` ON (`api`.`id` = `api_case`.`api_id`) WHERE `api_case`.`case_id` = 'xxx'

# 在关系表中使用子表的字段查询
API.objects.get(pk=3736).api_case_relate.all()
sql等于
SELECT case.* FROM  `case` INNER JOIN `api_case` ON (`case`.`id` = `api_case`.`case_id`) WHERE `api_case`.`api_id` = 'xxx'

2.4子表序列化

class APISerializer(serializers.ModelSerializer):
    # 使用钩子方法序列化
    cases = serializers.SerializerMethodField()
   # 使用目表的序列化器,很多地方这么说,但我试了不行. 
   # cases = CaseSerializer(many=True, read_only=True)

    class Meta:
        model = models.API
        # fields = '__all__'
        fields = ['id', 'name',..., 'cases']

    def get_cases(self, obj):
        cases = obj.api_case_relate.all()
        case_id = CaseSerializer(many=True, instance=cases)
        return case_id.data