我有一个Node js Express应用程序,在这里我从许多不同的地方(服务器,Twitter,另一个数据库等)设置cookie。这些都需要串行发生。为了避免回调的噩梦,我尝试使用Async.js。但是,在async.series调用完成之前,响应一直在发送。我如何确保async.series完成并然后调用res.redirect?
调用以异步模式
// OTHER CODE
accountCookies(req, res, next); // THE MODULE WITH ASYNC
res.redirect(302, 'https://' + req.host + '/account');
异步模块
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;
}
});
};
最佳答案
您需要等待async.series
完成后才能发送响应。这样做的通常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方。