//第一步

var express = require('express')
var multer  = require('multer')
var upload = multer({ dest: 'uploads/' })
 var app = express()

//第二步

app.post('/profile', upload.single('avatar'), function (req, res, next) {
  // req.file is the `avatar` file 
  // req.body will hold the text fields, if there were any 
})
 
app.post('/photos/upload', upload.array('photos', 12), function (req, res, next) {
  // req.files is array of `photos` files 
  // req.body will contain the text fields, if there were any 
})

var cpUpload = upload.fields([{ name: 'avatar', maxCount: 1 }, { name: 'gallery', maxCount: 8 }])
app.post('/cool-profile', cpUpload, function (req, res, next) {
  // req.files is an object (String -> Array) where fieldname is the key, and the value is array of files 
  // 
  // e.g. 
  //  req.files['avatar'][0] -> File 
  //  req.files['gallery'] -> Array 
  // 
  // req.body will contain the text fields, if there were any 
})

//注释

1.文件上传有以下方法
muilter.single(‘file’), //适用于单文件上传
muilter.array(‘file’,num), //适用于多文件上传，num为最多上传个数，上传文件的数量可以小于num,
muilter.fields(fields), //适用于混合上传，比如A类文件1个，B类文件2个。官方API有详细说明。
2.file为上传字段名称，当使用form表单submit方式上传时，必须与表单上传的name属性保持一致。
表单记得加上  enctype=‘multipart/form-data’