Question

我在MEAN STACK应用程序中工作，我想改进以下代码。

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 });
                }
            };

        });

我不想在评论中进行查询并逐步发布，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。

任何机构都可以为我提供改进此代码的指南。

感谢。

Answer 1

如果你有少量（2或3）异步操作，那么你可以使用promise chaining os，当第一次调用成功时，另一次启动。

如果您有两个以上的异步操作或更好的做法，您可以使用异步库。如果所有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，请使用async.waterfall

请检查：https://github.com/caolan/async

Answer 2

您需要某种异步控制库。正如@binariedMe所述，您可以使用bluebird这是一个基于承诺的库，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 3

以前执行的结果传递给下一个

时，会对async waterfall进行一些重构

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 4

这是我的代码版本。它使用promise，因此我们可以并行请求以获取帖子和评论。

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);      
    });
  });
}

希望有帮助

如何在nodejs中改进我的代码？

4 个答案: