Mongoengine，只搜索一些MapField [英] Mongoengine, retriving only some of a MapField

问题描述

例如..在Mongodb ..

For Example.. In Mongodb..

> db.test.findOne({}, {'mapField.FREE':1})
{
    "_id" : ObjectId("4fb7b248c450190a2000006a"),
    "mapField" : {
            "BOXFLUX" : {
                    "a" : "f",
            }
    }
}

mapField字段由Mongoengine的MapField制成。
和'mapField'字段有一个密钥和数据的日志..但是我只是检索'BOXFLUX'..

The 'mapField' field is made of MapField of Mongoengine. and 'mapField' field has a log of key and data.. but I just retrieved only 'BOXFLUX'..

这个查询在MongoEngine中不起作用....
例如..

this query is not working in MongoEngine.... for example..

BoxfluxDocument.objects( ~~ querying ~~ ).only('mapField.BOXFLUX')

AS你可以看到..
mapField.BOXFLUX'）或仅限（mapField__BOXFLUX）不起作用。
它检索所有'mapField'数据，包括'BOXFLUX'一个。

AS you can see.. only('mapField.BOXFLUX') or only only('mapField__BOXFLUX') does not work. it retrieves all 'mapField' data, including 'BOXFLUX' one..

如何仅检索MapField的一个字段？ / strong>

How can I retrieve only a field of MapField???

推荐答案

我看到有一张机票： https://github.com/hmarr/mongoengine/issues/508

适用于我是一个示例测试用例：

Works for me heres an example test case:

def test_only_with_mapfields(self):

    class BlogPost(Document):
        content = StringField()
        author = MapField(field=StringField())

    BlogPost.drop_collection()

    post = BlogPost(content='Had a good coffee today...', 
                    author={'name': "Ross", "age": "20"}).save()

    obj = BlogPost.objects.only('author__name',).get()

    self.assertEquals(obj.author['name'], "Ross")
    self.assertEquals(obj.author.get("age", None), None)

这篇关于Mongoengine，只搜索一些MapField的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！