MongoDB通过NodeJS中的索引更新文档的数组元素

Question

How can I increment the value of an specific element of an array of a MongoDB document in Meteor or nodeJS?

Say, I've following document:

{
    "_id" : "4tP6ewe4Z5kwYA3Je",
    "name" : "chutia",
    "address" : "shonir akhra",
    "itemCount" : "4",
    "items" : [ 
        "3", 
        "4",
        "13", 
        "24"
    ]
}

I need to increment the n 'th element of items array. Where n is a variable.

Answer 1

The right way to do this is:

{$inc: {[`items.${idx}`]: 1}}

Where idx is the array index. Courtesy MasterAM's comment

Answer 2

As documented here https://docs.mongodb.com/manual/reference/operator/update/inc/ , you can increment an element in an array by dot notation.

The following example increase the first element of items by 1.

db.<collection>.update(
 <query>,
 { $inc: { "items.0": 1 } }
)