MongoEngine:EmbeddedDocumentListField()和ListField(EmbeddedDocumentField())之间的区别?

时间:2018-05-02 11:29:30

标签: python mongoengine

标题。这两个陈述是做同样的事情,还是我在这里遗漏了什么?

cars = db.EmbeddedDocumentListField(Car, default= [])

VS

cars = db.ListField(db.EmbeddedDocumentField(Car), default=[])

1 个答案:

答案 0 :(得分:3)

EmbeddedDocumentListField支持在返回的嵌入文档列表中查询count(),filter(),delete(),create()等操作。因此,使用EmbeddedDocumentListField()而不是List(EmbeddedDocumentField())会更有利。

有关详细信息和方法列表,请参阅:

http://docs.mongoengine.org/apireference.html#embedded-document-querying

==编辑:更多详情==

以下是使用EmbeddedDocumentListField方法的示例,其中显示了如何将EmbeddedDocument添加到主文档模型中的EmbeddedDocumentListField 2级别:

model1_obj.model2_list.get(model2_id_field=model2_id).model3_list.create(**model3_data)

model1_obj.model2_list.filter(model2_id_field=model2_id).first().model3_list.create(**model3_data)

以下是与此代码段相关的模型和视图类:

  

models.py:

from mongoengine import *

class Model3(EmbeddedDocument):
    field1 = StringField()
    field2 = StringField()
    field3 = StringField()

class Model2(EmbeddedDocument):
    # other fields
    model2_id_field = # Some field
    model3_list = EmbeddedDocumentListField(Model3)

class Model1(Document):
    # other fields
    model2_list = EmbeddedDocumentListField(Model2)
  

views.py :(使用Django rest框架实现补丁方法)

class Model1AddModel3(APIView):
    def get_object(self, id):
        return Model1.objects.get(pk=id)

    def patch(self, request, id, format=None):
        model1_obj = self.get_object(id)
        #
        # Validate request.data here
        # Extract model2 identifier and model3 data from request.data
        # e.g.:
        # model2_id = request.data['model2id']
        # model3_data = {'field1': 'a', 'field2': 'a', 'field3': 'a', }
        #
        model1_obj.model2_list.get(model2_id_field=model2_id).model3_list.create(**model3_data)
        #
        # You can also use:
        # model1_obj.model2_list.filter(model2_id_field=model2_id).first().model3_list.create(**model3_data)
        #
        model1_obj.save()
        return Response(some_data, status=status.HTTP_201_CREATED)