Mongoose find()，如何访问结果文档? [英] Mongoose find(), how to access the result documents?

问题描述

我刚开始玩猫鼬和猫鼬.我有以下代码:

I just started playing with mongoose and mongo. I have the following code:

var ninjaSchema = mongoose.Schema({
    name: String,
    skill: Number
});

var Ninja = mongoose.model('Ninja',ninjaSchema);

module.exports = {
init : function(){
    console.log('Connecting to database');
    mongoose.connect('mongodb://localhost/mydb');
    var db = mongoose.connection;
    db.on('error', console.error.bind(console, 'connection error:'));
    db.once('open', function callback () {
      console.log('Successfully connected!');
    });
},
createNinja : function(name,skill){
    var n = new Ninja({name:name,skill:skill});
    n.save(function(err,n){
        if (err)
            console.log('saving failed');
        console.log('saved '+ n.name);
    });
},
getNinjas : function(){
    var res = null;
    res = Ninja.findOne({},'name skill',function(err,docs){
        if (err)
            console.log('error occured in the query');
        return 'ninja name: '+docs.name+' ninja skill: '+docs.skill;
    });

    return res;
}

向数据库添加条目没有问题，但检索它们时遇到问题.我对整个事情的运作方式有点困惑.我的理解如下:

There is no problem in adding entries to the database but I have problems retrieving them. I am a bit confused about how the whole thing works. My understanding is the following:

有模式，就像 oop 中的类，所以只是数据库中记录的蓝图.模型是一个记录，好吧，也许多一点，因为我看到你可以在模型中添加一个方法.嗯...我真的不明白如何使用它们.你能告诉我它们到底是什么吗?

There are the schemas, which are like classes in oop, so just a blueprint for a record in the database. The model is a record, OK, maybe a bit more, since I saw that you can add a method to the model. Well... I don't really understand how to use them. Can you give me a clue what really are they?

回到主题:发出find命令时，调用匿名函数，结果应该是docs吧?现在我如何访问它们?从现在开始，如果我记录资源，我会得到以下信息:

Back to the subject: When issuing the find command, it calls the anonymous function and docs should be the result right? Now how do I access them? Since now if I log the res I get the following:

{ options: {},
safe: undefined,
_conditions: {},
_updateArg: {},
_fields: { name: 1, skill: 1 },
_geoComparison: undefined,
op: 'findOne',
model: 
{ [Function: model]
 base: 
  { connections: [Object],
    plugins: [],
    models: [Object],
    modelSchemas: [Object],
    options: {} },
 modelName: 'Ninja',
 model: [Function: model],
 db: 
  { base: [Object],
    collections: [Object],
    models: {},
    replica: false,
    hosts: null,
    host: 'localhost',
    port: 27017,
    user: undefined,
    pass: undefined,
    name: 'mydb',
    options: [Object],
    _readyState: 1,
    _closeCalled: false,
    _hasOpened: true,
    _listening: true,
    _events: [Object],
    db: [Object] },
 schema: 
  { paths: [Object],
    subpaths: {},
    virtuals: [Object],
    nested: {},
    inherits: {},
    callQueue: [],
    _indexes: [],
    methods: {},
    statics: {},
    tree: [Object],
    _requiredpaths: [],
    options: [Object],
    _events: {} },
 options: undefined,
 collection: 
  { collection: [Object],
    opts: [Object],
    name: 'ninjas',
    conn: [Object],
    queue: [],
    buffer: false } } }

另外，如果我使用 Ninja.find(...,function(err,docs){ ... }) 我该如何浏览文档?或者我如何检索我的记录?

Also if I use Ninja.find(...,function(err,docs){ ... }) how do I go trough the docs? Or how do I retrieve my records?

推荐答案

我找到了问题所在.这更像是一个概念上的问题:我正在处理异步调用并试图从另一个函数返回结果，但不知道它何时会执行.所以发生的事情是我请求执行 db 查询并返回结果，结果为空.这段代码:

I've found the fault. It was more of a conceptual one: I am dealing with asynchronous calls and am trying to return the result from another function and don't know when it will execute. So what happens is I make the request that the db query be executed and return the result, which turns out to be null. This code:

getNinjas : function(){
    var res = null;
    Ninja.find({},'name skill',function(err,docs){
        if (err)
            console.log('error occured in the database');
        console.log(docs);
    });     
    return res;
}

返回 null，但是！console.log(docs) 将数据库中的所有值打印到控制台，这是我试图做的.现在我需要进行更改，很可能会传递一个回调，该回调将在接收到结果时执行.

returns null, but! the console.log(docs) prints to the console all the values from the database, what I was trying to do. Now I need to make changes, most likely pass a callback which will be executed upon the receiving of the results.

修改后的代码如下所示:

With the changes the code looks like this:

getNinjas : function(res){
    var twisted = function(res){
        return function(err, data){
            if (err){
                console.log('error occured');
                return;
            }
            res.send('My ninjas are:
');
            console.log(data);
        }
    }

    Ninja.find({},'name skill',twisted(res));
}

这样我就可以传递响应对象，这样我就可以发送我的忍者的名字:)

So like this I am able to pass the response object so I can send the name of my ninjas :)

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