在当前版本的 Mongoose 中，exec() 方法返回一个 Promise，因此您可以执行以下操作:

In the current version of Mongoose, the exec() method returns a Promise, so you can do the following:

exports.process = function(r) {
    return Content.find({route: r}).exec();
}

然后，当你想要获取数据时，你应该让它异步:

Then, when you would like to get the data, you should make it async:

app.use(function(req, res, next) {
     res.local('myStuff', myLib.process(req.path));
     res.local('myStuff')
         .then(function(doc) {  // <- this is the Promise interface.
             console.log(doc);
             next();
         }, function(err) {
             // handle error here.
         });
});

关于 Promise 的更多信息，我最近阅读了一篇精彩的文章:http://spion.github.io/posts/why-i-am-切换到promises.html

For more information about promises, there's a wonderful article that I recently read: http://spion.github.io/posts/why-i-am-switching-to-promises.html