REST 节点服务器有时会运行两次代码

Question

好吧，这看起来有点奇怪。但我有一个运行我的 REST API 的 Node 服务器。

我从我的 Angular 应用程序中调用 API，但有时如果我只是停留在同一页面上，最后一个已知请求会被执行多次。

我开始认为这只是我所在页面的问题，但现在经过很长时间，我发现无论我在应用程序中的哪个页面上都有问题。

有趣的是，虽然在我的前端控制台 (Chrome) 中调用没有被多次执行。

我的API 包含很多路由文件，但主要结构如下：

Server.js

    // BASE SETUP
// =============================================================================
var express = require('express'),
    bodyParser = require('body-parser');
var app = express();
var router = express.Router();
var es = require('express-sequelize');
var multer = require('multer');
var Excel = require("exceljs");
var ex = require('xlsjs');
var stream = require('stream');
var fs = require('fs');
var XLSX = require('xlsx');
var async = require('async');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
    extended: true
}));

// =============================================================================

//Secure

app.all('/*', function (req, res, next) {
    // CORS headers
    res.header("Access-Control-Allow-Origin", "*"); // restrict it to the required domain
    res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE,OPTIONS');
    // Set custom headers for CORS
    res.header('Access-Control-Allow-Headers', 'Content-type,Accept,X-Access-Token,X-Key');
    if (req.method == 'OPTIONS') {
        res.status(200).end();
    } else {
        next();
    }
});


var env = app.get('local') == 'development' ? 'dev' : app.get('env');
var port = process.env.PORT || 8080;

var Sequelize = require('sequelize');

// db config
var env = "local";
var config = require('./database.json')[env];
var password = config.password ? config.password : null;

// initialize database connection
var sequelize = new Sequelize(
    config.database,
    config.user,
    config.password,
    {
        port: config.port,
        host: config.server,
        logging: console.log,
        define: {
            timestamps: false
        }
    }
);

var user = {};

var done = {is_complete: false};

app.use(multer({
    dest: './uploads/',
    rename: function (fieldname, filename) {
        return filename + Date.now();
    },
    onFileUploadStart: function (file) {
        console.log(file.originalname + ' is starting ...')
    },
    onFileUploadComplete: function (file) {
        //Redirects request to path
    }
}));

var auth = require('./auth.js')(express, sequelize, router);

app.all('/api/*', [require('./middlewares/validateRequest')]);

app.use('/', router);
app.use(auth);


//Init models
var division_model = require('./lb_models/division/division_model')(express, sequelize, router, user, async);
var location_model = require('./lb_models/division/Location')(express, sequelize, router, user, async);
var user_model = require('./lb_models/user/user_model')(express, sequelize, router, user, async);
var title_model = require('./lb_models/title/Title')(express, sequelize, router, user, async);
var login_stat = require('./lb_models/user/Login')(express, sequelize, router, user, async);
var quote_model = require('./lb_models/Quote')(express, sequelize, router, user, async);
var organization_model = require('./lb_models/user/Organization')(express, sequelize, router, user, async);
var competence_model = require('./lb_models/competence/Competence')(express, sequelize, router, user, async, multer, done);
var competenceCategory_model = require('./lb_models/competence/CompetenceCategory')(express, sequelize, router, user, async, multer, done);
var level_model = require('./lb_models/competence/Level')(express, sequelize, router, user, async, multer, done);

/*
 Admin dashboard
 */
var admin_dash = require('./lb_models/dashboard/AdminDashboard')(express, sequelize, router, user, async);

/*
 Modules
 */
var category_model = require('./lb_models/module/Category')(express, sequelize, router, user, async);
var module_type = require('./lb_models/module/Type')(express, sequelize, router, user, async);
var module_model = require('./lb_models/module/Module')(express, sequelize, router, user, async);
var component_model = require('./lb_models/module/Component')(express, sequelize, router, user, async);

/*
 Academy
 */
var academy_model = require('./lb_models/academy/Academy')(express, sequelize, router, user, async);
var academyModule_model = require('./lb_models/academy/AcademyModule')(express, sequelize, router, user, async);
var academy_team = require('./lb_models/academy/Team')(express, sequelize, router, user, async);
var academy_course_model = require('./lb_models/academy/AcademyCourse')(express, sequelize, router, user, async);
var user_academy_model = require('./lb_models/academy/UserAcademy')(express, sequelize, router, user, async);

/*
 Stat
 */
var comp_stat = require('./lb_models/competence/CompetenceStat')(express, sequelize, router, user, async);
var userComp = require('./lb_models/competence/UserCompetence')(express, sequelize, router, user, async);
/*
 Screening
 */
var screening_model = require('./lb_models/screening/Screening')(express, sequelize, router, user, async);

/*
 Testview
 */
var answers = require('./lb_models/testview/Answer')(express, sequelize, router, user, async);
var medals = require('./lb_models/testview/Medal')(express, sequelize, router, user, async);

/*
 Course
 */
var courses = require('./lb_models/course/Course')(express, sequelize, router, user);
var reasons = require('./lb_models/course/Reason')(express, sequelize, router, user);

/*
    Material
 */
var material = require('./lb_models/material/Material')(express, sequelize, router, user);
var profileDocument = require('./lb_models/material/ProfileDocument')(express, sequelize, router, user);
/*
    Activity
 */
var activities = require('./lb_models/activity/Activity')(express, sequelize, router, user);

/*
 Analytics
 */
var activity_model = require('./lb_models/analytics/Activity')(express, sequelize, router, user, async);
var academyStat_model = require('./lb_models/analytics/Academy')(express, sequelize, router, user, async);
var teamStat_model = require('./lb_models/analytics/Team')(express, sequelize, router, user, async);
var academyReport_model = require('./lb_models/analytics/Report')(express, sequelize, router, user, async);
var analytics_user_model = require('./lb_models/analytics/User')(express, sequelize, router, user, async);
var analytics_overview = require('./lb_models/analytics/Overview')(express, sequelize, router, user, async);

var analytics_survey = require('./lb_models/analytics/Survey')(express, sequelize, router, user, async);


/*
 Self development
 */
var selfDevelopment_model = require('./lb_models/analytics/SelfDevelopment')(express, sequelize, router, user, async);

/*
 Benchmark
 */
var academyBenchmark_model = require('./lb_models/analytics/AcademyBenchmark')(express, sequelize, router, user, async);
/*
    Jeopardy
 */

var jeopardy_model = require('./lb_models/jeopardy/jeopardy')(express, sequelize, router, user, async);


app.use(division_model);
app.use(location_model);
app.use(user_model);
app.use(title_model);
app.use(quote_model);
app.use(organization_model);
app.use(login_stat);
app.use(competence_model);
app.use(competenceCategory_model);
app.use(level_model);

/*
 Admin Dashboard
 */
app.use(admin_dash);

/*
 Modules
 */
app.use(category_model);
app.use(module_type);
app.use(module_model);
app.use(component_model);

/*
 Academy
 */
app.use(academy_model);
app.use(academy_team);
app.use(academyModule_model);
app.use(academy_course_model);
app.use(user_academy_model);

/*
 Screening
 */
app.use(screening_model);

/*
 Stat
 */

app.use(comp_stat);
app.use(userComp);

/*
 Testview
 */
app.use(answers);
app.use(medals);

/*
 Course
 */
app.use(courses);
app.use(reasons);

/*
    Material
 */
app.use(material);
app.use(profileDocument);
/*
     Activity
 */
app.use(activities);

/*
 Analytics
 */
app.use(activity_model);
app.use(academyStat_model);
app.use(teamStat_model);
app.use(academyReport_model);
app.use(analytics_user_model);
app.use(analytics_overview);
app.use(analytics_survey);

/*
 Self development
 */
app.use(selfDevelopment_model);

/*
 Benchmark
 */
app.use(academyBenchmark_model);

/*
    Jeopardy
 */

app.use(jeopardy_model);

// If no route is matched by now, it must be a 404
app.use(function (req, res, next) {
    var err = new Error('Not Found');
    err.status = 404;
    next(err);
});

// START THE SERVER
app.listen(port);
console.log('Magic happens on port ' + port);

谁能告诉我为什么会这样？这是一个大问题，因为我的 create 语句会在我的数据库中创建多个项目！

其他信息

好的，我试过了。如果响应未决，请求是否会再次运行（意味着我不返回响应？？）

Answer 1

这是我的猜测，尽管您的问题缺乏足够的细节来确定 - 如果响应超时，许多浏览器会自动重试 XHR 请求。他们将为应该是幂等且可以安全重试的请求（包括 GET）执行此操作。当我延迟响应时，我看到了这一点，因为我有一个交互式调试器在断点处暂停服务器代码。如果您的 express 响应不够快，则 angular 可能会重试请求，这可能是您注意到的。

Answer 2

请检查：

• 您已启用 CORS，因此，如果您执行需要 cors 的请求，则浏览器将首先执行 OPTIONS 请求，然后执行请求（GET、POST、PUT 或 DELETE）。

Answer 3

当我使用app.all('*', ... 并通过 POST 方法请求时，同样的事情发生在我身上。我把app.get()和app.post()分开后，就再也没有了。

var router = function(res, req){
    console.log(req.method);
};

// run twice
app.all('*', router);

// run once
app.get('*', router);
app.post('*', router);

• 版本 express@4.13.4

Answer 4

似乎这是因为浏览器使Preflight OPTION request：

...“预检”请求首先通过 OPTIONS 发送 HTTP 请求 方法到另一个域上的资源，以确定 实际请求是否可以安全发送。

所以，app.all 匹配所有请求方法，这就是为什么你有双重代码执行。

解决方案：

我强烈建议您指定具有适当语义的请求方法。仅将 GET 用于获取数据（它不应更改服务器端的状态，POST - 仅用于更改服务器端的数据。否则您的网站可能会受到CSRF（参见“GET 场景”）攻击的攻击。