node.js - mongo更新嵌套结构中的内容

Question

一个questions表，存所有的问题，每一个question有一个answers的key，是个数组对象，每个answer有自己_id和一个up属性，现在想通过这个_id来更新up属性。
请问前辈们如何做？试了很多都没办法正确更新，谢谢qaq

Answer 1

db.questions.update({
    "answers._id": ObjectId("58f575ca09c601c45f6c281a")
}, {
    $set: {
        "answers.$.up": 1
    }
});

Note the $ operator, we call it Positional Operator, please see the link for more information.

Answer 2

I think you shouldn’t nest the data table so deeply. I think it’s more reasonable to build a relational table.

Answer 3

Okay, assuming you know the index of the answer you want to modify in the answers array, you can use question.answers.index.up to update it. If you don’t know the index now, you can use $ to place it, and use {answers._id for Filter. :123456} update using {answers.$.up:321}