MongoDB:子数组的Update属性仅更新第一个元素 [英] MongoDB: Update property of subarray just updates the first element

问题描述

匹配元素如下所示:

{
    "_id": {
        "$oid": "519ebd1cef1fce06f90e3157"
    },
    "from": "Tester2",
    "to": "Tester",
    "messages": [
        {
            "username": "Tester2",
            "message": "heeey",
            "read": false
        },
        {
            "username": "Tester",
            "message": "hi!",
            "read": false
        },
        {
            "username": "Tester2",
            "message": "test",
            "read": false
        }
    ],
}

现在，我尝试将用户名不等于Tester的子元素的read属性设置为当前日期:

Now I try to set the read property to the current date just of the subelements where the username is not equal to Tester:

var messages = db.collection('messages');
messages.update(
{
    _id: new BSON.ObjectID("519ebd1cef1fce06f90e3157"),
    messages: {
        $elemMatch: { username: { $ne: "Tester" } }
    }
},
{ $set: { 'messages.$.read': new Date() } },
{ multi: true }, function(error, result) {
    console.log(error);
    console.log(result);
});

但是只有第一个消息子元素read属性会更新:

But just the first messages subelement read property updates:

{
    "_id": {
        "$oid": "519ebd1cef1fce06f90e3157"
    },
    "from": "Tester2",
    "to": "Tester",
    "messages": [
        {
            "username": "Tester2",
            "message": "heeey",
            "read":  {
                "$date": "2013-01-01T00:00:00.000Z"
            }
        },
        {
            "username": "Tester",
            "message": "hi!",
            "read": false
        },
        {
            "username": "Tester2",
            "message": "test",
            "read": false
        }
    ],
}

代码有什么问题? 我正在使用node.js v0.10.8和MongoDB v2.4.3以及 node-mongodb-native .

What's wrong with the code? I'm using node.js v0.10.8 and MongoDB v2.4.3 together with node-mongodb-native.

推荐答案

您的代码没有任何问题. $运算符包含第一个匹配数组元素. {multi: true}选项仅使update适用于多个文档，而不适用于数组元素.要在单个update中更新多个数组元素，必须通过数字索引指定它们.

There's nothing wrong with your code; the $ operator contains the index of the first matching array element. The {multi: true} option only makes the update apply to multiple documents, not array elements. To update multiple array elements in a single update you must specify them by numeric index.

因此，您必须执行以下操作:

So you'd have to do something like this:

messages.update(    
    {
        _id: new BSON.ObjectID("519ebd1cef1fce06f90e3157")
    },
    { $set: { 
        'messages.0.read': new Date(),
        'messages.2.read': new Date()
    } },
    function (err, result) { ... }
);

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