如果项目不存在，则更新数组中的条目或添加到数组 [英] Update entry in an array or add to array if item doesn't exist

问题描述

我有一个具有如下结构的集合

I have a collection that has a structure that looks like the following

{ "_id" : "MHBk8q96vpuRYrAdn", 
    "circles" : { 
        "guests" : 3, 
        "properties" : [      
            {       
                "position" : {  "x" : 146, "y" : 70.5207970},  
                "name" : "circle-1" 
            },
            {       
                "position" : {  "x" : 200, "y" : 85},  
                "name" : "circle-2" 
            }  
        ], 
        "tables" : 1 
    } 
}

我需要能够更新 circles.properties.position 的位置(如果它按名称存在)，或者如果它不存在，则添加一个新条目.例如，更新circle-1"的位置，因为它存在，但为circle-3"添加一个具有名称和位置的新数组项.有可能实现这一目标吗?到目前为止，我只能使用 $push 推送到数组上，并且我在使用 $(query) 运算符时没有成功.谢谢.

I need to be able to either update the position of circles.properties.position if it exists by name, or add a new entry if it does not. For example, update the position of "circle-1" since it exists, but add a new array item for "circle-3" with a name and position. Is it possible to achieve this? So far I have only been able to push onto the array using $push, and I have messed around with the $(query) operator with no success. Thanks.

推荐答案

自从 MongoDB 不支持对数组进行更新插入 这可能很棘手.您可以尝试以下操作:

Since MongoDB doesn't support upserts to arrays it can be tricky. You can try something like below:

var query = {};
new_circle = { "position" : {  "x" : -1, "y" : -1}, "name" : "circle-1" };

db.foo.find(query).forEach(
    function(doc) {

        // Find index of 'circle-1'
        i = doc.circles.properties.map(
            function(el) { if (el.name == 'circle-1') return 1; else return -1;}
        ).indexOf(1);

        // Update if circle-1 in circles-properties 
        if (i != -1) {
            doc.circles.properties[i] = new_circle;
        }

        // If not push new
        else {
            doc.circles.properties.push(new_circle);
        }

        db.foo.save(doc);
    }
)

编辑

如果您不能使用 save 和 update 和 upsert 选项替换上面张贴的 if-else 块像这样应该可以解决问题:

If you cannot use save and update with upsert option replacing if-else block posted above with something like this should do the trick:

if (i != -1) {
    db.foo.update(
        {"_id" : doc._id, "circles.properties.name": "circle-1"},
        {$set: {"circles.properties.$.position": new_circle.position}}
}

else {
    db.foo.update(
        {"_id" : doc._id},
        {$push: {"properties": new_circle }}
    )
}

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