Node Multer unexpected field

Question

I m working on uploading a file to my app using the multer npm module   The multer function I have defined is to allow a single file uploaded to the file system   Everything works during run time  the issue is after I upload the file I get an error below   Any advice appreciated on where to look   Error   Unexpected field  Error  Unexpected field     at makeError  c  Users Dev WebstormProjects Crunch node modules multer lib make-error js 12 13      at wrappedFileFilter  c  Users Dev WebstormProjects Crunch node modules multer index js 39 19      at Busboy  lt anonymous gt   c  Users Dev WebstormProjects Crunch node modules multer lib make-middleware js 97 7      at Busboy emit  events js 118 17      at Busboy emit  c  Users Dev WebstormProjects Crunch node modules multer node modules busboy lib main js 31 35      at PartStream  lt anonymous gt   c  Users Dev WebstormProjects Crunch node modules multer node modules busboy lib types multipart js 205 13      at PartStream emit  events js 107 17      at HeaderParser  lt anonymous gt   c  Users Dev WebstormProjects Crunch node modules multer node modules busboy node modules dicer lib Dicer js 51 16      at HeaderParser emit  events js 107 17      at HeaderParser  finish  c  Users Dev WebstormProjects Crunch node modules multer node modules busboy node modules dicer lib HeaderParser js 70 8     app js  var multer   require  multer    var app   express    var fs   require  fs               var upload   multer   dest   upload      var type   upload single  file     app post   upload   type  function  req res      var tmp path   req files recfile path    var target path    uploads     req files recfile name  fs readFile tmp path  function err  data      fs writeFile target path  data  function  err          res render  complete               Index hbs   lt form action   upload  method  post  enctype  multipart form-data  gt       lt input type  file  name  recfile  placeholder  Select file   gt       lt br  gt       lt button gt Upload lt  button gt   lt  form gt    Package json    dependencies          body-parser     1 13 2        cookie-parser     1 3 5        debug     2 2 0        easy-zip    0 0 4        express     4 13 1        hbs     3 1 0        less-middleware    1 0 x        morgan     1 6 1        multer     1 0 0        serve-favicon     2 3 0

User · Answer

In my scenario this was happening because I renamed a parameter in swagger.yaml but did not reload the docs page.

Hence I was trying the API with an unexpected input parameter.
Long story short, F5 is my friend.

User · Answer

We have to make sure the type  file with name attribute should be same   as the parameter name passed in upload single  attr     var multer    require  multer    var upload   multer   dest   upload      var fs   require  fs         Permissible loading a single file       the value of the attribute  name  in the form of  recfile       var type   upload single  recfile     app post   upload   type  function  req res           When using the  single        data come in  req file  regardless of the attribute  name         var tmp path   req file path         The original name of the uploaded file       stored in the variable  originalname         var target path    uploads     req file originalname         A better way to copy the uploaded file        var src   fs createReadStream tmp path     var dest   fs createWriteStream target path     src pipe dest     src on  end   function     res render  complete          src on  error   function err    res render  error

User · Answer

Different file name which posted as  quot recfile quot  at  lt input type  quot file quot  name  recfile  placeholder  quot Select file quot   gt  and received as  quot file quot  at  upload single  file   Solution    make sure both sent and received file are similar upload single  recfile

User · Answer

Unfortunately  the error message doesn t provide clear information about what the real problem is   For that  some debugging is required   From the stack trace  here s the origin of the error in the multer package   function wrappedFileFilter  req  file  cb      if   filesLeft file fieldname     0   lt   0        return cb makeError  LIMIT UNEXPECTED FILE   file fieldname          filesLeft file fieldname  -  1   fileFilter req  file  cb      And the strange  possibly mistaken  translation applied here is the source of the message itself      LIMIT UNEXPECTED FILE    Unexpected field    filesLeft is an object that contains the name of the field your server is expecting  and file fieldname contains the name of the field provided by the client   The error is thrown when there is a mismatch between the field name provided by the client and the field name expected by the server   The solution is to change the name on either the client or the server so that the two agree   For example  when using fetch on the client     var theinput   document getElementById  myfileinput   var data   new FormData   data append  myfile  theinput files 0   fetch    upload     method  POST   body data       And the server would have a route such as the following     app post   upload   multer multerConfig  single  myfile   function req  res     res sendStatus 200      Notice that it is myfile which is the common name  in this example

User · Answer

In my case  I had 2 forms in differents views and differents router files  The first router used the name field with view one and its file name was  quot inputGroupFile02 quot   The second view had another name for file input  For some reason Multer not allows  you set differents name in different views  so I dicided to use same name for the file input in both views

User · Answer

The  lt NAME gt  you use in multer s upload single  lt NAME gt   function must be the same as the one you use in  lt input type  file  name   lt NAME gt       gt    So you need to change  var type   upload single  file    to  var type   upload single  recfile    in you app js  Hope this helps

User · Answer

probably you are not giving the same name as you mentioned in the  upload single  file

User · Answer

A follow up to vincent s answer    Not a direct answer to the question since the question is using a form    For me  it wasn t the name of the input tag that was used  but the name when appending the file to the formData    front end file      var formData   new FormData       formData append   lt NAME gt   this new attachments    web service file      app post   upload   upload single   lt NAME gt

User · Answer

since 2 images are getting uploaded  one with file extension and other  file without extension  to delete tmp path  file without extension   after  src pipe dest     add below code   fs unlink tmp path     deleting the tmp path

User · Answer

I solve this issues looking for the name that I passed on my request  I was sending on body     thumbbail   lt myimg gt     and I was expect to   upload single  thumbnail     so  I fix the name that a send on request

User · Answer

This for the Api you could use   const express          require  express     const bodyParser       require  body-parser     const app   express     var multer   require  multer     const port   8000   app use bodyParser json      app use bodyParser urlencoded   extended  true        app listen port      gt    console log  We are live on    port          var upload   multer  dest    upload        app post   post   upload single  file    function req  res      console log req file    res send  file saved on server           This also works fine used on Postman but the file doesn t comes with  jpg extension  any Advice  As commented below   This is the default feature of multer if uploads file with no extension  however  provides you the the file object  using which you can update the extension of the file   var filename   req file filename   var mimetype   req file mimetype   mimetype   mimetype split        var filetype   mimetype 1    var old file   configUploading settings rootPathTmp filename   var new file   configUploading settings rootPathTmp filename     filetype   rname old file new file

[node.js] Node Multer unexpected field

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