使用 multer 上传多个文件，但来自不同的字段？答案

【问题标题】：Uploading multiple files with multer, but from different fields?使用 multer 上传多个文件，但来自不同的字段？
【发布时间】：2021-04-26 15:34:19
【问题描述】：

如何让 multer 接受来自多个文件类型字段的文件？

我有以下代码上传单个文件，在 node.js 中使用 multer：

var storage =   multer.diskStorage({
  destination: function (req, file, callback) {
    callback(null, './public/uploads');
  },
  filename: function (req, file, callback) {
    callback(null, file.fieldname + '-' + Date.now());
  }
});

var upload = multer({ storage : storage });

app.post('/rest/upload', upload.array('video', 1), function(req, res, next){
    ...
}

从下面的表格中，在只有视频字段有值的情况下（如果我同时指定两者，我会收到“意外字段”错误）：

<form action="/rest/upload" method="post" enctype="multipart/form-data">
   <label>Video file: </label> <input type="file" name="video"/> 
   <label>Subtitles file: </label> <input type="file" name="subtitles"/> 
   <input type="submit"/>
</form>

从文档中不清楚如何处理这个问题？任何建议，将不胜感激。顺便说一句，我尝试了以下参数变化，但没有成功：

app.post('/rest/upload', [upload.array('video', 1), upload.array('subtitles', 1)] ...
app.post('/rest/upload', upload.array('video', 1), upload.array('subtitles', 1), ...
app.post('/rest/upload', upload.array(['video', 'subtitles'], 1),  ...

【问题讨论】：

标签： node.js multer

【解决方案1】：

如果您想从同一个表单上传多个文件/图像，我使用了下面的代码，它工作正常。图像的路径存储在数据库中；我将跳过数据库路径，直接进入上传功能以及字段如何传递给保存功能。

    const path = require('path');
    const multer = require('multer');
    const storage = multer.diskStorage({
        destination: (req, file, cb) => {
           if (file.fieldname === "profile") {
               cb(null, './uploads/profiles/')
           }
           else if (file.fieldname === "natid") {
               cb(null, './uploads/ids/');
           }
           else if (file.fieldname === "certificate") {
               cb(null, './uploads/certificates/')
           }
        },
        filename:(req,file,cb)=>{
            if (file.fieldname === "profile") {
                cb(null, file.fieldname+Date.now()+path.extname(file.originalname));
            }
          else if (file.fieldname === "natid") {
            cb(null, file.fieldname+Date.now()+path.extname(file.originalname));
          }
          else if (file.fieldname === "certificate") {
            cb(null, file.fieldname+Date.now()+path.extname(file.originalname));
          }
        }
    });
    const upload = multer({
        storage: storage,
        limits: {
            fileSize: 1024 * 1024 * 10
        },
        fileFilter: (req, file, cb) => {
            checkFileType(file, cb);
        }
    }).fields(
        [
            {
                name:'profile',
                maxCount:1
            },
            {
                name: 'natid', maxCount:1
            },
            {
                name: 'certificate', maxCount:1
            }
        ]
    );
    
    function checkFileType(file, cb) {
        if (file.fieldname === "certificate") {
            if (
                file.mimetype === 'application/pdf' ||
                file.mimetype === 'application/msword' ||
                file.mimetype === 'application/vnd.openxmlformats-officedocument.wordprocessingml.document'
              ) { // check file type to be pdf, doc, or docx
                  cb(null, true);
              } else {
                  cb(null, false); // else fails
              }
        }
        else if (file.fieldname === "natid" || file.fieldname === "profile") {
            if (
                file.mimetype === 'image/png' ||
                file.mimetype === 'image/jpg' ||
                file.mimetype === 'image/jpeg'||
                fiel.mimetype==='image/gif'
              ) { // check file type to be png, jpeg, or jpg
                cb(null, true);
              } else {
                cb(null, false); // else fails
              }
            }
        }
    //at the save function 

 upload(req, res, (err) => {
        if (err) {
            console.log(err);
        } else {
            if (req.file == "undefined") {
                console.log("No image selected!")
            } else {
                let datecreated = new Date();
                let fullnames = req.body.firstname + ' ' + req.body.lastname;
                let formatedphone = '';
                let phone = req.body.personalphone;
                if (phone.charAt(0) == '0') {
                    formatedphone = '+254' + phone.substring(1);
                } else if ((phone.charAt(0) == '+') && (phone.length > 12 || phone.length <= 15)) {
                    formatedphone = phone
                }
                let teachers = {
                    "teacherid": teacherid,
                    "schoolcode": req.body.schoolcode,
                    "fullnames": fullnames,
                    "email": req.body.email,
                    "dateofbirth": req.body.dateofbirth,
                    "nationalid": req.body.nationalid,
                    "personalphone": formatedphone,
                    "profile": req.files.profile[0].path,
                    "natid": req.files.natid[0].path,
                    "certificate":req.files.certificate[0].path
                }
                connection.query('INSERT INTO teachers SET ?', teachers, (error, results, fields) => {`enter code here`
                    if (error) {
                        res.json({
                            status: false,
                            message: 'there are some error with query'
                        })
                        console.log(error);
                    } else {console.log("Saved successfully");
}

【讨论】：

你能解释一下这个代码块末尾发生了什么吗？至少，缩进似乎已关闭。但是，似乎还有一个与该功能无关的配置块。我想这就是您对将其放在save() 函数中的评论吗？如果是这样，我建议将其分解为单独的代码块。
这里是完整的保存功能：下面
谢谢！您可以（并且在这种情况下应该）编辑您的答案，以将 Save() 函数作为同一答案的一部分。这样，它们就不会随着时间的流逝而分离。你能做到吗？
您的答案应该包括解释，正如 mhmdk 在他们的回答中所做的那样。以目前的形式，它有被否决的风险。

【解决方案2】：

这对我有用。完整的例子

var multer = require('multer')
var storage = multer.diskStorage({


destination: function(req, file, callback) {
    callback(null, './public/audio');
  },
  filename: function(req, file, callback) {
    console.log(file);
    if(file.originalname.length>6)
      callback(null, file.fieldname + '-' + Date.now() + file.originalname.substr(file.originalname.length-6,file.originalname.length));
    else
      callback(null, file.fieldname + '-' + Date.now() + file.originalname);

  }
});

const upload = multer({ storage: storage });


router.post('/save/audio',upload.fields([{
  name: 'audio', maxCount: 1
}, {
  name: 'graphic', maxCount: 1
}]) ,(req, res) => {
  
  const audioFile = req.files.audio[0];
  const audioGraphic = req.files.graphic[0];
  const fileName = req.body.title;


  saveAudio(fileName,audioFile.filename,audioGraphic.filename,req.body.artist,function (error,success) {
    req.flash('success','File Uploaded Successfully')

    res.redirect('/')
  });

})

【讨论】：

【解决方案3】：

upload(req, res, (err) => {
        if (err) {
            console.log(err);
        } else {
            if (req.file == "undefined") {
                console.log("No image selected!")
            } else {
                let datecreated = new Date();
                let fullnames = req.body.firstname + ' ' + req.body.lastname;
                let formatedphone = '';
                let phone = req.body.personalphone;
                if (phone.charAt(0) == '0') {
                    formatedphone = '+254' + phone.substring(1);
                } else if ((phone.charAt(0) == '+') && (phone.length > 12 || phone.length <= 15)) {
                    formatedphone = phone
                }
                let teachers = {
                    "teacherid": teacherid,
                    "schoolcode": req.body.schoolcode,
                    "fullnames": fullnames,
                    "email": req.body.email,
                    "dateofbirth": req.body.dateofbirth,
                    "nationalid": req.body.nationalid,
                    "personalphone": formatedphone,
                    "profile": req.files.profile[0].path,
                    "natid": req.files.natid[0].path,
                    "certificate":req.files.certificate[0].path
                }
                connection.query('INSERT INTO teachers SET ?', teachers, (error, results, fields) => {
                    if (error) {
                        res.json({
                            status: false,
                            message: 'there are some error with query'
                        })
                        console.log(error);
                    } else {

console.log('保存成功');}

【讨论】：

【解决方案4】：

使用 Multer 从不同页面上不同表单的两个字段上传文件在此示例中，我有两个字段 - 简历和图像。以一种形式恢复，以另一种形式恢复图像。两者都在不同的页面上。首先导入依赖

const path = require('path'); // for getting file extension
const multer = require('multer'); // for uploading files
const uuidv4 = require('uuidv4'); // for naming files with random characters

定义fileStorage和fileFilter：

const fileStorage = multer.diskStorage({
  destination: (req, file, cb) => { // setting destination of uploading files        
    if (file.fieldname === "resume") { // if uploading resume
      cb(null, 'resumes');
    } else { // else uploading image
      cb(null, 'images');
    }
  },
  filename: (req, file, cb) => { // naming file
    cb(null, file.fieldname+"-"+uuidv4()+path.extname(file.originalname));
  }
});

const fileFilter = (req, file, cb) => {
  if (file.fieldname === "resume") { // if uploading resume
    if (
      file.mimetype === 'application/pdf' ||
      file.mimetype === 'application/msword' ||
      file.mimetype === 'application/vnd.openxmlformats-officedocument.wordprocessingml.document'
    ) { // check file type to be pdf, doc, or docx
      cb(null, true);
    } else {
      cb(null, false); // else fails
    }
  } else { // else uploading image
    if (
      file.mimetype === 'image/png' ||
      file.mimetype === 'image/jpg' ||
      file.mimetype === 'image/jpeg'
    ) { // check file type to be png, jpeg, or jpg
      cb(null, true);
    } else {
      cb(null, false); // else fails
    }
  }
};

multer的中间件

app.use(
  multer(
    { 
      storage: fileStorage, 
      limits:
        { 
          fileSize:'2mb' 
        }, 
      fileFilter: fileFilter 
    }
  ).fields(
    [
      { 
        name: 'resume', 
        maxCount: 1 
      }, 
      { 
        name: 'image', 
        maxCount: 1 
      }
    ]
  )
);

然后调用你的路线。为了安全起见，您可能需要同时添加 csrf 保护或身份验证。但这应该可以正常工作。

【讨论】：

非常感谢您的澄清，它帮助我更好地理解。如果出现错误（disallow if statements as the only statement in else blocks (no-lonely-if)），您可以通过使用三元运算符来修复它，以及我使用的控制器上的问题resume: req.files.resume, image: req.files.image

【解决方案5】：

你要的是upload.fields():

app.post('/rest/upload',
         upload.fields([{
           name: 'video', maxCount: 1
         }, {
           name: 'subtitles', maxCount: 1
         }]), function(req, res, next){
  // ...
}

【讨论】：

缺少扩展名，请更改。谢谢
@RishavKumar 你能详细说明一下吗？您是指文件扩展名还是说 API 已更改或？

【解决方案6】：

您是否尝试使用multer().any()？

【讨论】：

我没有，尽管我会使用 uploads.fields() 方法，因为文档表明 any() 从处理和安全的角度来看可能不是最好的方法。