Question

我有一个Node js Express应用程序，我从许多不同的地方（服务器，Twitter，另一个数据库等）设置cookie。这些都需要连续发生。为了避免回调噩梦，我试图使用Async.js。但是，在async.series调用完成之前，响应会继续发送。如何确保async.series完成，然后调用res.redirect？

使用ASYNC调用模块

// OTHER CODE
accountCookies(req, res, next);  // THE MODULE WITH ASYNC
res.redirect(302, 'https://' + req.host + '/account');

ASYNC MODULE

module.exports = function (req, res, next) {

req.appVariables.error = null;

// Required modules
var async = require(__dirname + '/utilities-----async.js'); // Utility for controlling node's asynchronous behavior
var userSessionObject = {};
// ...OTHER MODULES

// Cookie values set by the server
var cookieValuesSetByTheServer = function(req, res, next, userSessionObject, callback) {
    userSessionObject.STUFF = STUFF;
    logs.dev('cookieValuesSetByTheServer');
    setTimeout(function(){callback(req.appVariables.error, '1');}, 3000);
};

// Cookie values from Twitter
var cookieValuesFromTwitter = function(req, res, next, userSessionObject, callback) {
    userSessionObject.moreSTUFF = moreSTUFF;
    logs.dev('cookieValuesFromTwitter')
    callback(req.appVariables.error, '2');
};

// Cookie values from User Database
var cookieValuesFromUserDatabase = function(req, res, next, userSessionObject, callback) {
    userSessionObject.otherSTUFF = otherSTUFF;
    logs.dev('cookieValuesFromUserDatabase');
    setTimeout(function(){callback(req.appVariables.temporarilyUnavailableCalled, '3');}, 6000);
};

// Call all functions in Series
async.series([
    function(callback){
        cookieValuesSetByTheServer(req, res, next, userSessionObject, callback);
    },
    function(callback){
        cookieValuesFromTwitter(req, res, next, userSessionObject, callback);
    },
    function(callback){
        cookieValuesFromUserDatabase(req, res, next, userSessionObject, callback);
    }
], function(err, results){
    if ( err == null ) {
        logs.dev(results);
        return true;
    }
    else {
        logs.dev(err);
        return false;
    }
});

};

Answer 1

您需要等待async.series完成才能发送回复。通常的方法是传递一个回调函数：

accountCookies(req, res, next, function theCallbackFunction(success) {
  res.redirect(302, 'https://' + req.host + '/account');
});

// in your async module
module.exports = function (req, res, next, theCallbackFunction) {
  ...
  async.series([ ... ], function(err, results) {
    if ( err == null ) {
      logs.dev(results);
      theCallbackFunction(true);
    } else {
      logs.dev(err);
      theCallbackFunction(false);
    }
  });
};

换句话说：您不能在异步函数中使用return将返回值传递回调用者。

Answer 2

您可以尝试使用只执行next的中间件功能替换res.redirect回调，然后传递请求。

accountCookies(req, res, function(req, res, next) {
    res.redirect(302, 'https://' + req.host + '/account');
    next();
});

节点js async.series无法使用Express应用程序---响应过早发生

2 个答案: