MongoDB 和 mongoose:如果对象不存在，如何添加它 [英] MongoDB and mongoose: how to add an object if it doesn't already exist

问题描述

我在使用 mongoDB/mongoose 和 node.js 时遇到了一些问题.我习惯了 SQL，而 mongoDB 是......很难！这是我的架构:

I am having some trouble with mongoDB/mongoose and node.js. I am used to SQL, and mongoDB is...hard! Here is my schema:

var mongoose = require('mongoose');

var mongoose = require('mongoose');

mongoose.Promise = global.Promise;

mongoose.Promise = global.Promise;

var itemSchema= mongoose.Schema({

    item_info        : {
        user_id      : Number,
        location     : String,
        item_id      : Number,
        title        : String
    },
    item_hist        : {
        user_id      : Number,
        location     : String,
        item_id      : Number,
        founddate    : String
       }
});
module.exports = mongoose.model('item', itemSchema);

我可以通过这样做添加一个新项目:

And I can add a new item by doing this:

    var item= require('./app/models/item');
    var item= new item();
    item.item_info.user_id      =  12345;
    item.item_info.location     = 'This address';
    item.item_info.item_id      = 4444;
    item.item_info.title        = 'New item';
    item.save(function(err) 
    {
        if (err)    throw err;
    });

我希望能够做的是说:查找 item_info.item_id 5555 的项目.如果它存在，什么都不做.如果它不存在，则将其添加到数据库."我已经阅读了很多 mongodb 和 mongoose 文档，但是在使用点符号和通过 nodejs 而不是命令行 mongodb 访问之间，我仍然无法弄清楚如何做到这一点.SQL 看起来简单多了！

What I want to be able to do is say: "look for an item with item_info.item_id 5555. if it exists, do nothing. if it doesn't exist, then add it to the database." I've read through so much mongodb and mongoose documentation, but between using dot notation and accessing through nodejs instead of command line mongodb, I still can't figure out how to do this. SQL seemed so much easier!

推荐答案

就用这个 -

    var query = { user_id: 12345, location: "This address", item_id: 4444, title: "New item"  },

        options = { upsert: true };

   Model.findOneAndUpdate(query.item_id, query, options, function(error, result) {
    if (error) return;

    // do something with the document
});

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