MongoDB:无法规范化查询:BadValue投影不能混合包含和排除 [英] MongoDB: Can't canonicalize query: BadValue Projection cannot have a mix of inclusion and exclusion

问题描述

我在使用CakePHP的MongoDB中较新.

I am newer in MongoDB with CakePHP.

当我编写以下查询时，它将执行得很好.

When I write the following query it will execute very well.

db.testData.find()
{
    "_id" : ObjectId("53d1f79db8173a625961ff3d"),
    "name" : "sadikhasan",
    "created" : ISODate("2014-07-25T06:22:21.701Z")
}

当我运行以下查询以仅获取name时，它返回错误:

When I run the following query to get only name, it returns an error:

db.testData.find({},{name:1, created:0})
error: {
    "$err" : "Can't canonicalize query: BadValue Projection cannot 
              have a mix of inclusion and exclusion.",
    "code" : 17287
}

当我运行以下查询以仅获取name和_id:0时，它执行得很好:

When I run the following query to get only name with _id:0, then it executes well:

db.testData.find({},{name:1, _id:0})
{ "name" : "sadikhasan" }

我的问题是，为什么在投影列表中写created:0时出现错误.谢谢您的帮助.

My question is, why I am getting an error when I write created:0 in the projection list. Thanks for help in advance.

推荐答案

您不能混合使用包含和排除，仅例外是_id字段.

You cannot mix inclusion and exclusion, the only exception is the _id field.

例如，如果您有以下内容:

For example if you have this:

{
   "_id": ObjectId("53d1fd30bdcf7d52c0d217de"),
   "name": "bill",
   "birthdate": ISODate("2014-07-80T00:00:00.000Z"),
   "created": ISODate("2014-07-25T06:44:38.641Z")
}

如果您只想输入姓名"和生日"，则需要这样做:

If all you want is the "name" and "birthdate" you need to do this:

db.collection.find({},{ "_id": 0, "name": 1, "birthdate": 1 })

或者这个:

db.collection.find({},{ "_id": 0, "created": 0 })

但是除"_id"外，不允许混合"其他任何操作

But it is not allowed to "mix" any other operations other than "_id"

db.collection.find({},{ "_id": 0, "name": 1, "created": 0 })

那也会产生一个错误.

手册页.

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