如何改进我在 nodejs 中的代码？

Question

我正在使用 MEAN STACK 应用程序，我想改进我的以下代码。

app.js

var express = require("express");
var router = express.Router();
var Comments = require('../models/Comments');
var Posts = require('../models/Posts');

//use in strict mode
'use strict';

//get user comments and posts
router
    .route("/api/user/getUserCommentsAndPosts")
    .get(
        function(req, res) {

            /*define variable to run sendResponse() function after completed both comment and post query*/
            var commentProcess = 0; //comment process not completed
            var postProcess = 0;   //post process not completed

            /*for store comments and post data in this variable for use in sendResponse() function*/
            var commentGlobal;
            var postGlobal;


            Comments.find({ user_id: req.payload.id }, function(err, CommentsData) {
                if (err) {
                    res.json({ status: 0, code: 200, type: "error", message: err });
                } else {

                    commentProcess = 1; //comment process is completed
                    commentGlobal = CommentsData; //assign local object to global object
                    sendResponse(); // call this function for send api response
                }
            });


            Posts.find({ user_id: req.payload.id }, function(err, PostsData) {
                if (err) {
                    res.json({ status: 0, code: 200, type: "error", message: err });
                } else {

                    postProcess = 1; //post process not completed
                    postGlobal = PostsData; //assign local object to global object
                    sendResponse(); // call this function for send api response
                }
            });

            //run this function after every process
            var sendResponse = function() {
                // check for all process is completed  if completed then send api response
                if (commentProcess !== 0 && postProcess !== 0) {
                    var data ={comments : commentGlobal, posts : postGlobal};
                    res.json({ status: 1, code: 200, type: "success", data: data });
                }
            };

        });

我不想在评论和帖子中一步一步地进行查询，因此我不能说最后会完成哪个过程。

如上所述，我必须制作这种类型的代码。

任何机构都可以给我一个改进此代码的指南吗？

谢谢。

Answer 1

您需要某种异步控制库。正如@binariedMe 所说，您可以使用bluebird，这是一个基于promise 的库，或者您可以使用async，这是一组具有集中错误处理的不同控制流方法。

Answer 2

当上一次执行的结果被传递到下一次时，这里是使用async waterfall 进行的一些重构

var express = require("express");
var router = express.Router();
var Comments = require('../models/Comments');
var async = require('async');
var Posts = require('../models/Posts');

//use in strict mode
'use strict';

//get user comments and posts
router
    .route("/api/user/getUserCommentsAndPosts")
    .get(function(req, res) {

    async.waterfall([
        function(callback) {

            Comments.find({ user_id: req.payload.id }, function(err, CommentsData) {
                if (err) {
                    callback(err);
                } else {

                    var commentProcess = 1; //comment process is completed
                    var commentGlobal = CommentsData; //assign local object to global object

                    callback(null, commentProcess, commentGlobal);
                }
            });


        },
        function(commentProcess, commentGlobal, callback) {
            Posts.find({ user_id: req.payload.id }, function(err, PostsData) {
                if (err) {
                    callback(err);
                } else {

                    var postProcess = 1; //post process not completed
                    var postGlobal = PostsData; //assign local object to global object

                    callback(null, commentProcess, commentGlobal, postProcess, postGlobal);

                }
            });
        }
    ], function (err, commentProcess, commentGlobal, postProcess, postGlobal) {
        if (err) {
            res.json({ status: 0, code: 200, type: "error", message: err });
        } else {
            var data ={comments : commentGlobal, posts : postGlobal};
            res.json({ status: 1, code: 200, type: "success", data: data });
        }
    });


});

Answer 3

如果您的异步操作很少（2 或 3 个），那么您可以使用 Promise 链接操作系统，当第一次调用成功时，另一个会启动。

如果您有两个以上的异步操作，或者作为更好的做法，您可以使用异步库。 如果您所有的异步操作都是独立的，那么用户 async.parallel。 如果您希望它们按特定顺序执行，则使用 async.waterfall

请查看：https://github.com/caolan/async

Answer 4

这是我的代码版本。它使用 Promise，因此我们可以发出并行请求来获取帖子和 cmets。

const express = require("express");
const router = express.Router();
const Comments = require('../models/Comments');
const Posts = require('../models/Posts');

//use in strict mode
'use strict';

//get user comments and posts
router
  .route("/api/user/getUserCommentsAndPosts")
  .get(
    function (req, res) {
      const userId = req.payload.id; // use const is better than var

      // Do parallel requests using promise.all, it speed up your app indeed
      Promise.all([
        findCommentsByUserId(userId),
        findPostsByUserId(userId)
      ]).then((comments, posts) => {        
        res.json({
          status: 1,
          code: 200,
          type: "success",
          data: { comments, posts }
        });
      })
      .catch(err => {
        res.json({
          status: 0,
          code: 200,
          type: "error",
          message: err
        });
      });      
    });

/**
 * Find comments by user Id
 * - We make this function as promise so we later can do parallel request
 * - We move it to function to make your code in router cleaner and easier to read
 * @param userId 
 */
function findCommentsByUserId(userId) {
  return new Promise((resolve, reject) => {  
    Comments.find({
      user_id: userId
    }, function (err, CommentsData) {
      if (err) {
        reject(err);
      }        

      resolve(CommentsData);      
    });
  });
}

/**
 * Find posts by user Id
 * We make this function as promise so we can later can do parallel request
 * @param userId 
 */
function findPostsByUserId(userId) {
  return new Promise((resolve, reject) => {  
    Posts.find({
      user_id: userId
    }, function (err, PostsData) {
      if (err) {
        reject(err);
      }        

      resolve(PostsData);      
    });
  });
}

希望对你有帮助