Question

我有db-conn.js我将db connection存储在function中，然后require将其存储在create.js文件中call 。

我想要的是将pass代码的其余部分callback作为connects，以便首先insertion到数据库，然后执行var mongo = {} /**************************************************/ mongo.doConnection = (fcallback) => { mongo = require('mongodb').MongoClient global.db = null sDatabasePath = 'mongodb://localhost:27017/kea' global.mongoId = require('mongodb').ObjectID /**************************************************/ mongo.connect(sDatabasePath, (err, db) => { if (err) { console.log('ERROR 003 -> Cannot connect to the database') return false } global.db = db console.log('OK 002 -> Connected to the database') }) } /**************************************************/ module.exports = mongo 。

由于我不善于回调，我不知道该怎么做。你能帮我吗？

这就是db-conn.js：

var mongo = require(__dirname + '/db-conn.js')
/**************************************************/
mongo.doConnection()// I am not sure what to do here 
createStudent = () => {
    var jStudent =
        {
            "firstName": "Sarah",
            "lastName": "Jepsen",
            "age": 27,
            "courses": [
                {
                    "courseName": "Web-development",
                    "teachers": [
                        {
                            "firstName": "Santiago",
                            "lastName": "Donoso"
                        }
                    ]
                },

                {
                    "courseName": "Databases",
                    "teachers": [
                        {
                            "firstName": "Dany",
                            "lastName": "Kallas"
                        },
                        {
                            "firstName": "Rune",
                            "lastName": "Lyng"
                        }
                    ]
                },
                {
                    "courseName": "Interface-Design",
                    "teachers": [
                        {
                            "firstName": "Roxana",
                            "lastName": "Stolniceanu"
                        }
                    ]
                }
            ]
        }
    global.db.collection('students').insertOne(jStudent, (err, result) => {
        if (err) {
            var jError = { "status": "error", "message": "ERROR -> create.js -> 001" }
            console.log(jError)
        }
        var jOk = { "status": "ok", "message": "create.js -> saved -> 000" }
        console.log(jOk)
        console.log(JSON.stringify(result))
    })
}

这是create.js：

module.exports = {
   function1: functions(parm1, callback){
       if (checkParm1(parm1)) {
           //do something
       }else{
           //do something else
       }
       callback();
   }
};

function checkParm1(parm1){
    return ( parm1 === 'abc' );
}

Answer 1

在db-conn.js中完成连接后，您需要调用fcallback回调。

mongo.connect(sDatabasePath, (err, db) => {
    if (err) {
        console.log('ERROR 003 -> Cannot connect to the database')
        return fcallback(err, null);
    }
    global.db = db
    console.log('OK 002 -> Connected to the database')
    return fcallback(null, db);
})

然后在create js中你需要添加一个回调函数作为mongo.doConnection(...)的参数，当连接完成时调用它（调用fcallback）

使用此回调，您可以确保在连接完成时调用createStudent。

mongo.doConnection( (err, db) => {
    if(err){
      console.error("error connection to db: " + err;
      return;
    }
    createStudent = () => {
        var jStudent =
            { } ...

});

如何将函数作为Node.js中另一个函数的回调传递？

1 个答案: