Return promise after mongoose model saving-CodePudding

I am trying to return a promise after model saving in mongoose.

Here is the schema of the User Document :

const mongoose = require("mongoose");
const Schema = mongoose.Schema;

const UserSchema = new mongoose.Schema({
    first_name:String,
    last_name:String,
    phone_number:String,
    email:{type:String, unique:true, required:true, lowercase:true},
    account_status: Boolean,
    hash:String,
    salt:String,
});

module.exports = UserSchema;

Here is the code of the User Model:


const mongoose = require("mongoose");
const userSchema = require("./UserSchema");
const userModel = new mongoose.model("User", userSchema);
module.exports = userModel;

Here is the code to save a User Object :

const UserModel = require("../models/user/UserModel");

function UserController(){}

UserController.prototype.addUser = function(user_datas){
    var new_user = new UserModel();
    new_user.first_name = user_datas.first_name;
    new_user.last_name = user_datas.last_name;
    new_user.phone_number = user_datas.phone_number;
    new_user.email = user_datas.email;
    new_user.account_status = false;
    new_user.hash = user_datas.hash;
    new_user.save(function(err, user){
        if(err){
            /** 
               Some customs code before returning the promise 
            **/

            return new Promise(function(resolve, reject){
                reject(err);
                resolve(null);
            });
        }
        
        if(user){

            /** 
               Some customs code before returning the promise 
            **/

            return new Promise(function(resolve, reject){
                resolve(user);
                reject(null);
            });
        }
    });
}

The function addUser always return undefined instead of a promise. What i want is a promise that resolve the User Object created and reject an error if it occured.

Any idea ?

Thanks in advance.

CodePudding user response：

What's happening in your code is that when you return the Promise, that is actually the return value of the callback function passed to new_user.save().

If you want your addUser function to return a Promise that resolves to a User object, you wrap the new_user.save() inside of a Promise and return that instead.

UserController.prototype.addUser = function(user_datas){
    var new_user = new UserModel();
    new_user.first_name = user_datas.first_name;
    new_user.last_name = user_datas.last_name;
    new_user.phone_number = user_datas.phone_number;
    new_user.email = user_datas.email;
    new_user.account_status = false;
    new_user.hash = user_datas.hash;

    return new Promise(function(resolve, reject) {
        new_user.save(function(err, user) {
            if (err) {
                reject(err);
            } else {
                resolve(user);
            }
        });
    });
}

CodePudding user response：

Wrap whole addUser function in return new Promise() then inside save callback resolve/reject