在DBRef类型上的mongodb查询 [英] mongodb query on DBRef type

问题描述

如何在mongodb shell中的有效mongodb查询中打开此查询.

How do I turn this query in a valid mongodb Query in mongodb shell.

{ 'cars.owner.$ref' : 'users' } 

cars.owner是此处的DBRef，但$ref无效

cars.owner is a DBRef here, but $ref is invalid

我收到此错误:

"$err" : "Positional operator does not match the query specifier."

我在这里的目的是弄清楚是否有其他收藏家和用户拥有"的汽车.

My objective here is to figure out if there are any cars "owned" by different collections then users.

推荐答案

<parameterName>: DBRef("CollectionName", "_id Value")

放入集合.然后创建一个以实名作为ParameterName的Bean，并放置morphia orm的@Reference批注，然后执行所需的操作

put in collection.Then Create a Bean having feild name as parameterName, and put @Reference annotation of morphia orm then do operations you want

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