浅谈KOA2 Restful方式路由初探

来源：jb51　　时间：2019/3/15 8:33:55　　对本文有异议

前言

最近考虑将服务器资源整合一下，作为多端调用的API

看到Restful标准和ORM眼前一亮,但是找了不少版本路由写的都比较麻烦，于是自己折腾了半天

API库结构

考虑到全部对象置于顶层将会造成对象名越来长，同时不便于维护，故采取部分的分层结构

如workflow模块内的prototypes,instances等等，分层的深度定义为层级

可访问的对象集合(collection)的属性满足Restful设计

 -- workflow(category)
  -- prototypes(collection)
    -- [method] ...
    -- [method] ... 
  -- instances(collection)
 -- users(collection)
   --[method] List     #get :object/
   --[method] Instance   #get :object/:id
 -- ...
 -- ...

RESTFUL API 接口

将Restful API接口进行标准化命名

.get('/', ctx=>{ctx.error('路径匹配失败')})        
.get('/:object', RestfulAPIMethods.List)
.get('/:object/:id', RestfulAPIMethods.Get)
.post('/:object', RestfulAPIMethods.Post)
.put('/:object/:id', RestfulAPIMethods.Replace)
.patch('/:object/:id', RestfulAPIMethods.Patch)
.delete('/:object/:id', RestfulAPIMethods.Delete)
.get('/:object/:id/:related', RestfulAPIMethods.Related)
.post('/:object/:id/:related', RestfulAPIMethods.AddRelated)
.delete('/:object/:id/:related/:relatedId', RestfulAPIMethods.DelRelated)

API对象

这个文件是来自微信小程序demo，觉得很方便就拿来用了，放于需要引用的根目录，引用后直接获得文件目录结构API对象

const _ = require('lodash')
const fs = require('fs')
const path = require('path')
 
/**
 * 映射 d 文件夹下的文件为模块
 */
const mapDir = d => {
  const tree = {}
 
  // 获得当前文件夹下的所有的文件夹和文件
  const [dirs, files] = _(fs.readdirSync(d)).partition(p => fs.statSync(path.join(d, p)).isDirectory())
 
  // 映射文件夹
  dirs.forEach(dir => {
    tree[dir] = mapDir(path.join(d, dir))
  })
 
  // 映射文件
  files.forEach(file => {
    if (path.extname(file) === '.js') {
      tree[path.basename(file, '.js')] = require(path.join(d, file))
      tree[path.basename(file, '.js')].isCollection = true
    }
  })
 
  return tree
}
 
 
 
// 默认导出当前文件夹下的映射
module.exports = mapDir(path.join(__dirname))

koa-router分层路由的实现

创建多层路由及其传递关系

执行顺序为

1 -- 路径匹配
    -- 匹配到‘/'结束
    -- 匹配到对应的RestfulAPI执行并结束
    -- 继续
2 -- 传递中间件 Nest
3 -- 下一级路由
4 -- 循环 to 1

const DefinedRouterDepth = 2
let routers = []
for (let i = 0; i < DefinedRouterDepth; i++) {
  let route = require('koa-router')()
  if (i == DefinedRouterDepth - 1) {
    // 嵌套路由中间件
    route.use(async (ctx, next) => {
      // 根据版本号选择库
      let apiVersion = ctx.headers['api-version']
      ctx.debug(`------- (API版本 [${apiVersion}]) --=-------`)
       if (!apiVersion) {
        ctx.error('版本号未标记')
        return
      }
      let APIRoot = null
      try {
        APIRoot = require(`../restful/${apiVersion}`)
      } catch (e) {
        ctx.error ('API不存在,请检查Header中的版本号')
        return
      }
      ctx.debug(APIRoot)
      ctx.apiRoot = APIRoot
      ctx.debug('---------------------------------------------')
      // for(let i=0;i<)
      await next()
    })
  }
  route
    .get('/', ctx=>{ctx.error('路径匹配失败')})
    .get('/:object', RestfulAPIMethods.List)
    .get('/:object/:id', RestfulAPIMethods.Get)
    .post('/:object', RestfulAPIMethods.Post)
    .put('/:object/:id', RestfulAPIMethods.Replace)
    .patch('/:object/:id', RestfulAPIMethods.Patch)
    .delete('/:object/:id', RestfulAPIMethods.Delete)
    .get('/:object/:id/:related', RestfulAPIMethods.Related)
    .post('/:object/:id/:related', RestfulAPIMethods.AddRelated)
    .delete('/:object/:id/:related/:relatedId', RestfulAPIMethods.DelRelated)
 
 
  if (i != 0) {
    route.use('/:object', Nest, routers[i - 1].routes())
  }
  routers.push(route)
}
let = router = routers[routers.length - 1]

Nest中间件

将ctx.apiObject设置为当前层的API对象

const Nest= async (ctx, next) => {
  let object = ctx.params.object
  let apiObject = ctx.apiObject || ctx.apiRoot
  if(!apiObject){
    ctx.error('API装载异常')
    return
  }
 
  if (apiObject[object]) {
    ctx.debug(`ctx.apiObject=>ctx.apiObject[object]`)
    ctx.debug(apiObject[object])
    ctx.debug(`------------------------------------`)
    ctx.apiObject = apiObject[object]
  } else {
    ctx.error(`API接口${object}不存在`)
    return
  }
 
 
  await next()
}

RestfulAPIMethods

let RestfulAPIMethods = {}
let Methods = ['List', 'Get', 'Post', 'Replace', 'Patch', 'Delete', 'Related', 'AddRelated', 'DelRelated']
for (let i = 0; i < Methods.length; i++) {
  let v = Methods[i]
  RestfulAPIMethods[v] = async function (ctx, next) {
    
    let apiObject = ctx.apiObject || ctx.apiRoot
    if (!apiObject) {
      ctx.error ('API装载异常')
      return
    }
    let object = ctx.params.object
    if (apiObject[object] && apiObject[object].isCollection) {
      ctx.debug(` --- Restful API [${v}] 调用--- `)
      if (typeof apiObject[object][v] == 'function') {
        ctx.state.data = await apiObject[object][v](ctx)
        ctx.debug('路由结束')
        return
        //ctx.debug(ctx.state.data)
      } else {
        ctx.error(`对象${object}不存在操作${v}`)
        return
      }
    }
    ctx.debug(` --- 当前对象${object}并不是可访问对象 --- `)
    await next()
  }
}