Question

我希望使快速路线更加模块化。我有兴趣使用承诺读取文件然后返回路线。

以下是代码：

var express = require('express')
var router = express.Router()
var app = express()

var Promise = require("bluebird")
var fs = Promise.promisifyAll(require("fs"))

function promiseRoute(file){
  return fs.readFileAsync(file, "utf8")
  .then(JSON.parse)
  .then(function(file){
    if(!file.url) throw new Error("missing url")
    router.get(file.url, function(req, res, next){
      return res.redirect("/hello")
    })
    return router
  })
}

app.use(promiseRoute("../file.json"))

var server = app.listen(3000, function () {})

也尝试了

promiseRoute(path.join(__dirname, "./file.json")).then(app.use)

我收到了这个错误。

throw new TypeError('app.use() requires middleware functions')

这是有希望的。

Unhandled rejection TypeError: Cannot read property 'lazyrouter' of undefined
    at use (/project/node_modules/express/lib/application.js:213:7)
    at tryCatcher (/project/node_modules/bluebird/js/main/util.js:24:31)
    at Promise._settlePromiseFromHandler (/project/node_modules/bluebird/js/main/promise.js:489:31)
    at Promise._settlePromiseAt (/project/node_modules/bluebird/js/main/promise.js:565:18)
    at Promise._settlePromises (/project/node_modules/bluebird/js/main/promise.js:681:14)
    at Async._drainQueue (/project/node_modules/bluebird/js/main/async.js:123:16)
    at Async._drainQueues (/project/node_modules/bluebird/js/main/async.js:133:10)
    at Immediate.Async.drainQueues [as _onImmediate] (/project/node_modules/bluebird/js/main/async.js:15:14)
    at processImmediate [as _immediateCallback] (timers.js:371:17)

还试过这个：

promiseRoute(path.join(__dirname, "./file.json")).then(function(router){
  app.use(function(req, res, next){
    return router
  })
})

如何将承诺/路线返回app.use？

Answer 1

app.use需要中间件功能。也就是说，一个需要(req, res, next)的函数。

总的来说：

app.use(function(req, res, next){
     promiseRoute(probably_pass_things_in).nodeify(next);
});

nodeify是将保证转换为回调next。请注意，您可以使用第三方承诺中间件。

Answer 2

这就是诀窍：

promiseRoute(path.join(__dirname, "./file.json")).then(function(router){
  app.use(router)
})

将承诺的包裹快递路线返回app.use（）

2 个答案: