当函数需要访问外部范围变量时,更好的方法来处理Promise流

Question

我正在创建一个Node.js模块来与我的API进行交互,我使用superagent模块来执行请求.这个怎么运作:

module.exports = data => {
  return getUploadUrl()
    .then(uploadFiles)
    .then(initializeSwam)

  function getUploadUrl() {
    const request = superagent.get(....)
    return request
  }

  function uploadFiles(responseFromGetUploadUrl) {
    const request = superagent.post(responseFromGetUploadUrl.body.url)
    // attach files that are in data.files
    return request
  }

  function initializeSwam(responseFromUploadFilesRequest) {
    // Same thing here. I need access data and repsonseFromUploadFilesRequest.body
  }
}

我觉得我做错了,但我想不出更好的方法来达到同样的效果.

Answer 1

两种简单方法:

1. 编写你的函数来获取它需要的所有参数

   const doStuff = data =>
     getUploadUrl()
     .then(uploadFiles)
     .then(initializeSwam)
   

   可能成为

   const doStuff = data =>
     getUploadUrl()
       .then(parseResponseUrl) // (response) => response.body.url
       .then(url => uploadFiles(data, url))
       .then(parseResponseUrl) // same function as above
       .then(url => initializeSwam(data, url))
   

这应该工作得很好(或者很好,取决于你在那些功能中挥手的东西).

2. 部分应用你的功能

   const uploadFiles = (data) => (url) => {
     return doOtherStuff(url, data);
   };
   
   // same deal with the other
   const doStuff = data =>
     getUploadUrl()
       .then(parseResponseUrl)
       .then(uploadFiles(data)) // returns (url) => { ... }
       .then(parseResponseUrl)
       .then(initializeSwam(data));
   

所有这些技术(合理的时间和地点)的混合应该足以满足您的许多需求.