How to return a file using Web API

Question

I am using ASP NET Web API   I want to download a PDF with C  from the API  that the API generates    Can I just have the API return a byte    and for the C  application can I just do   byte   pdf   client DownloadData  urlToAPI        and   File WriteAllBytes

User · Answer

Example with IHttpActionResult in ApiController    HttpGet   Route  file  id      public IHttpActionResult GetFileForCustomer int id        if  id    0        return BadRequest         var file   GetFile id        IHttpActionResult response      HttpResponseMessage responseMsg   new HttpResponseMessage HttpStatusCode OK       responseMsg Content   new ByteArrayContent file SomeData       responseMsg Content Headers ContentDisposition   new System Net Http Headers ContentDispositionHeaderValue  attachment        responseMsg Content Headers ContentDisposition FileName   file FileName      responseMsg Content Headers ContentType   new MediaTypeHeaderValue  application pdf        response   ResponseMessage responseMsg       return response      If you don t want to download the PDF and use a browsers built in PDF viewer instead remove the following two lines   responseMsg Content Headers ContentDisposition   new System Net Http Headers ContentDispositionHeaderValue  attachment    responseMsg Content Headers ContentDisposition FileName   file FileName

User · Answer

Better to return HttpResponseMessage with StreamContent inside of it   Here is example   public HttpResponseMessage GetFile string id        if  String IsNullOrEmpty id           return Request CreateResponse HttpStatusCode BadRequest        string fileName      string localFilePath      int fileSize       localFilePath   getFileFromID id  out fileName  out fileSize        HttpResponseMessage response   new HttpResponseMessage HttpStatusCode OK       response Content   new StreamContent new FileStream localFilePath  FileMode Open  FileAccess Read        response Content Headers ContentDisposition   new System Net Http Headers ContentDispositionHeaderValue  attachment        response Content Headers ContentDisposition FileName   fileName      response Content Headers ContentType   new MediaTypeHeaderValue  application pdf         return response      UPD from comment by patridge  Should anyone else get here looking to send out a response from a byte array instead of an actual file  you re going to want to use new ByteArrayContent someData  instead of StreamContent  see here

User · Answer

Another way to download file is to write the stream content to the response s body directly   HttpGet  quot pdfstream  id  quot    public async Task  GetFile long id                var stream   GetStream id       Response StatusCode    int HttpStatusCode OK      Response Headers Add  HeaderNames ContentDisposition    quot attachment  filename   quot  Guid NewGuid    pdf  quot  quot         Response Headers Add  HeaderNames ContentType   quot application pdf quot                      await stream CopyToAsync Response Body       await Response Body FlushAsync

User · Answer

Just a note for  Net Core  We can use the FileContentResult and set the contentType to application octet-stream if we want to send the raw bytes  Example    HttpGet   id     public IActionResult GetDocumentBytes int id        byte   byteArray   GetDocumentByteArray id       return new FileContentResult byteArray   application octet-stream

User · Answer

I ve been wondering if there was a simple way to download a file in a more      generic  way  I came up with this   It s a simple ActionResult that will allow you to download a file from a controller call that returns an IHttpActionResult  The file is stored in the byte   Content  You can turn it into a stream if needs be   I used this to return files stored in a database s varbinary column       public class FileHttpActionResult   IHttpActionResult               public HttpRequestMessage Request   get  set             public string FileName   get  set            public string MediaType   get  set            public HttpStatusCode StatusCode   get  set             public byte   Content   get  set             public Task lt HttpResponseMessage gt  ExecuteAsync CancellationToken cancellationToken                        HttpResponseMessage response   new HttpResponseMessage StatusCode                response StatusCode   StatusCode              response Content   new StreamContent new MemoryStream Content                response Content Headers ContentDisposition   new ContentDispositionHeaderValue  attachment                response Content Headers ContentDisposition FileName   FileName              response Content Headers ContentType   new MediaTypeHeaderValue MediaType                return Task FromResult response

User · Answer

I made the follow action    HttpGet   Route  api DownloadPdfFile  id     public HttpResponseMessage DownloadPdfFile long id        HttpResponseMessage result   null      try               SQL File file   db Files Where b   gt  b ID    id  SingleOrDefault             if  file    null                        result   Request CreateResponse HttpStatusCode Gone                     else                          sendo file to client             byte   bytes   Convert FromBase64String file pdfBase64                 result   Request CreateResponse HttpStatusCode OK               result Content   new ByteArrayContent bytes               result Content Headers ContentDisposition   new System Net Http Headers ContentDispositionHeaderValue  attachment                result Content Headers ContentDisposition FileName   file name     pdf                      return result            catch  Exception ex                return Request CreateResponse HttpStatusCode Gone

[c#] How to return a file using Web API?

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