How to set up a Web API controller for multipart form-data

Question

I am trying to figure this out  I was not getting any useful error messages with my code so I used something else to generate something  I have attached that code after the error message   I have found a tutorial on it but I do not know how to implement it with what I have  This is what I currently have   public async Task lt object gt  PostFile                 if   Request Content IsMimeMultipartContent                throw new Exception              var provider   new MultipartMemoryStreamProvider            var result   new   file   new List lt object gt               var item   new File             item CompanyName   HttpContext Current Request Form  companyName            item FileDate   HttpContext Current Request Form  fileDate            item FileLocation   HttpContext Current Request Form  fileLocation            item FilePlant   HttpContext Current Request Form  filePlant            item FileTerm   HttpContext Current Request Form  fileTerm            item FileType   HttpContext Current Request Form  fileType             var manager   new UserManager lt ApplicationUser gt  new UserStore lt ApplicationUser gt  new ApplicationDbContext              var user   manager FindById User Identity GetUserId              item FileUploadedBy   user Name          item FileUploadDate   DateTime Now           await Request Content ReadAsMultipartAsync provider            ContinueWith async  a    gt                          foreach  var file in provider Contents                                  if  file Headers ContentLength  gt  1000                                          var filename   file Headers ContentDisposition FileName Trim                             var contentType   file Headers ContentType ToString                         await file ReadAsByteArrayAsync   ContinueWith b   gt    item FilePdf   b Result                                                        Unwrap             db Files Add item           db SaveChanges            return result           Error      Object  message   The request entity s media type  multipart form-data  is not supported for this resource    exceptionMessage   No MediaTypeFormatter is available to read an obje   om content with media type  multipart form-data     exceptionType   System Net Http UnsupportedMediaTypeException   stackTrace    at System Net Http HttpContentExtensions ReadAs   atterLogger  CancellationToken cancellationToken   exceptionMessage   No MediaTypeFormatter is available to read an object of type  HttpPostedFileBase  from content with media type  multipart form-data   exceptionType   System Net Http UnsupportedMediaTypeException message   The request entity s media type  multipart form-data  is not supported for this resource  stackTrace    at System Net Http HttpContentExtensions ReadAsAsync T  HttpContent content  Type type  IEnumerable1 formatters  IFormatterLogger formatterLogger  CancellationToken cancellationToken       at System Net Http HttpContentExtensions ReadAsAsync HttpContent content  Type type  IEnumerable1 formatters  IFormatterLogger formatterLogger  CancellationToken cancellationToken     Code used to generate error message        HttpPost      public string UploadFile HttpPostedFileBase file                 if  file ContentLength  gt  0                        var fileName   Path GetFileName file FileName               var path   Path Combine HttpContext Current Server MapPath    uploads    fileName               file SaveAs path                       return   uploads     file FileName          Class   public class File       public int FileId   get  set        public string FileType   get  set        public string FileDate   get  set        public byte   FilePdf   get  set        public string FileLocation   get  set        public string FilePlant   get  set        public string FileTerm   get  set        public DateTime  FileUploadDate   get  set        public string FileUploadedBy   get  set         public string CompanyName   get  set        public virtual ApplicationUser User   get  set

User · Answer

This is what solved my problem Add the following line to WebApiConfig cs  config Formatters XmlFormatter SupportedMediaTypes Add new System Net Http Headers MediaTypeHeaderValue  multipart form-data

User · Answer

5 years later on and  NET Core 3 1 allows you to do specify the media type like this    HttpPost   Consumes  multipart form-data    public IActionResult UploadLogo         return Ok

User · Answer

Here s another answer for the ASP Net Core solution to this problem    On the Angular side  I took this code example    https   stackblitz com edit angular-drag-n-drop-directive     and modified it to call an HTTP Post endpoint    prepareFilesList files  Array lt any gt          const formData   new FormData        for  var i   0  i  lt  files length  i             formData append  quot file   quot   files i               let URL    quot https   localhost 44353 api Users quot       this http post URL  formData  subscribe        data   gt    console log data            error   gt    console log error             With this in place  here s the code I needed in the ASP Net Core WebAPI controller   HttpPost  public ActionResult Post       try         var files   Request Form Files       foreach  IFormFile file in files                if  file Length    0              continue                   string tempFilename   Path Combine Path GetTempPath    file FileName           System Diagnostics Trace WriteLine   quot Saved file to   tempFilename  quot             using  var fileStream   new FileStream tempFilename  FileMode Create                         file CopyTo fileStream                       return new OkObjectResult  quot Yes quot          catch  Exception ex          return new BadRequestObjectResult ex Message          Shockingly simple  but I had to piece together examples from several  almost-correct  sources to get this to work properly

User · Answer

You re  getting HTTP 415  The request entity s media type  multipart form-data  is not supported for this resource   because you haven t mention the correct content type in your request

User · Answer

check ur WebApiConfig and add this      GlobalConfiguration Configuration Formatters XmlFormatter SupportedMediaTypes Clear

User · Answer

You can use something like this   HttpPost  public async Task lt HttpResponseMessage gt  AddFile         if   Request Content IsMimeMultipartContent                  this Request CreateResponse HttpStatusCode UnsupportedMediaType              string root   HttpContext Current Server MapPath    temp uploads        var provider   new MultipartFormDataStreamProvider root       var result   await Request Content ReadAsMultipartAsync provider        foreach  var key in provider FormData AllKeys                foreach  var val in provider FormData GetValues key                         if  key     companyName                                 var companyName   val                                        On upload  files are given a generic name like  BodyPart 26d6abe1-3ae1-416a-9429-b35f15e6e5d5         so this is how you can get the original file name     var originalFileName   GetDeserializedFileName result FileData First          var uploadedFileInfo   new FileInfo result FileData First   LocalFileName       string path   result FileData First   LocalFileName         Do whatever you want to do with your file here      return this Request CreateResponse HttpStatusCode OK  originalFileName       private string GetDeserializedFileName MultipartFileData fileData        var fileName   GetFileName fileData       return JsonConvert DeserializeObject fileName  ToString       public string GetFileName MultipartFileData fileData        return fileData Headers ContentDisposition FileName

User · Answer

I normally use the HttpPostedFileBase parameter only in Mvc Controllers  When dealing with ApiControllers try checking the HttpContext Current Request Files property for incoming files instead    HttpPost  public string UploadFile         var file   HttpContext Current Request Files Count  gt  0           HttpContext Current Request Files 0    null       if  file    null  amp  amp  file ContentLength  gt  0                var fileName   Path GetFileName file FileName            var path   Path Combine              HttpContext Current Server MapPath    uploads                fileName                     file SaveAs path              return file    null     uploads     file FileName   null

User · Answer

Perhaps it is late for the party  But there is an alternative solution for this is to use ApiMultipartFormFormatter plugin   This plugin helps you to receive the multipart formdata content as ASP NET Core does   In the github page  demo is already provided

[c#] How to set up a Web API controller for multipart/form-data

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