Mongodb 错误:位置运算符未从查询中找到所需的匹配项 [英] Mongodb error: The positional operator did not find the match needed from the query

问题描述

我有一个像这样的对象的集合

I have a collection with objects like this

{
    "_id" : ObjectId("5742be02289512cf98bf63e3"),
    "name" : "test1",
    "attributes" : [ 
        {
            "name" : "x",
            "color" : "0xd79c9c",
            "_id" : ObjectId("5742be02289512cf98bf63e8")
        }, 
        {
            "name" : "y",
            "color" : "0xd79c9c",
            "_id" : ObjectId("5742be02289512cf98bf63e7")
        }, 
        {
            "name" : "z",
            "color" : "0xd79c9c",
            "_id" : ObjectId("5742be02289512cf98bf63e6")
        }
    ],
    "__v" : 6
}

而且我想更新所有文档，并为每个属性设置新字段.所以我想运行一个查询来一次更新所有文档.我想，这个查询会做

And I want to update all documents, and set for each attribute new field. So I want to run a single query to update all documents at once. I think, this query will do

db.spaces.update({}, { $set: { "attributes.0.weight": 2 } }, {multi: true})

但是当我运行这个查询时，我得到一个错误:

But when I run this query, I get an error:

代码":16837，
错误消息": "位置运算符没有找到查询所需的匹配.未扩展更新:attributes.$.weight"

"code" : 16837,
"errmsg" : "The positional operator did not find the match needed from the query. Unexpanded update: attributes.$.weight"

我不明白为什么.请帮忙

I can't understand why. Please help

推荐答案

为了使用 位置运算符.

例如，如果您想更新第一个数组元素，即使用 { "attributes.name": "x" } 那么您可以遵循以下模式:

For example, if you want to update the first array element i.e. with { "attributes.name": "x" } then you could follow the pattern:

db.spaces.update(
   { "attributes.name": "x" }, // <-- the array field must appear as part of the query document.
   { "$set": { "attributes.$.weight": 2 } },
   { "multi": true }
)

对于较新的 MongoDB 版本 3.2.X，您可以使用 updateMany() 方法根据上面的过滤器更新集合中的多个文档.

For the newer MongoDB versions 3.2.X, you could use the updateMany() method to update multiple documents within the collection based on the filter above.

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