如何防止MongoDB在查找文档时返回对象ID? [英] How to prevent MongoDB from returning the object ID when finding a document?

问题描述

我在 MongoDB 中有以下文档...

I've the following document in MongoDB...

{
  "_id" : ObjectId("531221cd960100960116b992"),
  "username : "joe",
  "address" : [
    {
      "zip" : "8000",
      "city" : "Zurich"
    },
    {
      "zip" : "6900",
      "city" : "Lugano"
    }
  ]
}

... 并检索第二个地址，我使用以下语句:

... and to retrieve the second address I use the following statement:

db.users.find({ _id: ObjectId("531221cd960100960116b992") }, { addresses: { $slice: [0, 1] } } )

除了返回对象 id 外，这有效:

This works except it also returns the object id:

{ "addresses" : [ { "zip" : "6900", "city" : "Lugano" } ], "_id" : ObjectId("531221cd960100960116b992") }

如何防止 MongoDB 返回对象 ID?我知道我应该提供一个像 _id : 0 这样的投影......但是我应该把它放在上面的表达式中的什么位置?我做了很多尝试……但都没有成功.

How do I prevent MongoDB from returning the object id? I know I should provide a projection like _id : 0... but where should I put it in the expression above? I did a number of tries... but without success.

谢谢.

推荐答案

这与@hanleyhansen 的答案完全相同，但只是为了让您知道您可以将 0 与 false 互换使用，例如:

This is exactly the same as @hanleyhansen's answer, but just to let you know that you can use 0 interchangeably with false like:

db.users.find(
  { _id: ObjectId("531221cd960100960116b992")},
  { addresses: { $slice: [0, 1] } ,'_id': 0}
)

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