Node.js 在中间件承诺完成之前运行的路由

我的代码和一些中间件有问题。我有一个函数，可以为用户获取导航项列表，并将它们存储在res.locals中。然而，出于某种原因，我现在遇到了一个几天前还没有出现的问题。My app.get（“/”函数在中间件承诺完成之前运行

这是我的路线代码：

const isAuthenticated = require("../config/middleware/isAuthenticated"); 
module.exports = function(app) {

    app.get('/', isAuthenticated, function(req, res) {
        res.locals.title = 'Welcome';
        res.render('index.ejs');
    });
}

我的中间件：

// This is middleware for restricting routes a user is not allowed to visit if not logged in
const Utils = require('../../models/Utils/utils');
module.exports = function(req, res, next) {
  // If the user is logged in, continue with the request to the restricted route
  if (req.user) {
    res.locals.user = {first_name: req.user.first_name, last_name: req.user.last_name};
    if(!res.locals.nav) {
        let navPromise = Utils.createNavs(req.user.id);
        navPromise.then(function(navItems) {
            res.locals.nav = navItems;
        });
    }
    return next();
  }
  // If the user isn't' logged in, redirect them to the login page
  return res.redirect("/login");
};

---

你知道为什么这可能不起作用吗？

根据我上面的评论，这应该能更好地发挥作用-即只有在

navPromise

问题解决后才调用下一个中间件/路由

module.exports = function(req, res, next) {
  // If the user is logged in, continue with the request to the restricted route
  if (req.user) {
    res.locals.user = {first_name: req.user.first_name, last_name: req.user.last_name};
    if(!res.locals.nav) {
        let navPromise = Utils.createNavs(req.user.id);
        navPromise.then(function(navItems) {
            res.locals.nav = navItems;
            next()
        });
    }
    return;
  }
  // If the user isn't' logged in, redirect them to the login page
  return res.redirect("/login");
};

---

根据我上面的评论，这应该可以更好地工作-即只有当

navPromise

解决了问题时，才调用队列中的下一个中间件/路由

module.exports = function(req, res, next) {
  // If the user is logged in, continue with the request to the restricted route
  if (req.user) {
    res.locals.user = {first_name: req.user.first_name, last_name: req.user.last_name};
    if(!res.locals.nav) {
        let navPromise = Utils.createNavs(req.user.id);
        navPromise.then(function(navItems) {
            res.locals.nav = navItems;
            next()
        });
    }
    return;
  }
  // If the user isn't' logged in, redirect them to the login page
  return res.redirect("/login");
};

---

您正在中间件中同步调用next（），而promise回调是异步执行的在您的中间件中同步-而promise回调是异步执行的。非常感谢！现在来了解为什么路由会被调用两次。非常感谢！现在来了解为什么路由会被调用两次。