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()?
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;
}
UPDATE 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).
new ByteArrayContent(someData) instead of StreamContent (see here). –
Diffractive ByteArrayContent better than response.BinaryWrite? –
Adequacy Response.BinaryWrite. I'm guessing it would be throwing bytes at the stream directly rather than managing content using the Web API pipeline you have in place. If you have other processing steps in that API pipeline that need to run on the content before it heads down the wire, you may want to stick with ByteArrayContent. Best I can offer is to suggest you see what works best for your situation. –
Diffractive fileSize variable used for in the above code? Should/could this be sent in the response headers? –
Crossbred 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");
}
FileContentResult called FileDownloadName to specify the filename –
Backdate 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 => 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);
}
}
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;
var file = GetFile(id);. file.SomeData is a Byte Array (byte[]) and file.FileNameis string. –
Ladanum You Can try , HttpClient for Download file from another side and same time you can pass as File Result
[HttpGet]
[Route("api/getFile")]
public async Task<FileResult> GetFile(string Param1,string Param2)
{
try
{
Stream stream = null;
string strURL = @"File URL";
HttpClient client = new HttpClient();
HttpResponseMessage httpResponse = await client.GetAsync(strURL);
Stream streamToReadFrom = await httpResponse.Content.ReadAsStreamAsync();
return File(streamToReadFrom, "{MIME TYPE}");
}
catch (Exception ex)
{
throw ex;
}
finally
{
}
}
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<HttpResponseMessage> 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);
}
}
Another way to download file is to write the stream content to the response's body directly:
[HttpGet("pdfstream/{id}")]
public async Task GetFile(long id)
{
var stream = GetStream(id);
Response.StatusCode = (int)HttpStatusCode.OK;
Response.Headers.Add( HeaderNames.ContentDisposition, $"attachment; filename=\"{Guid.NewGuid()}.pdf\"" );
Response.Headers.Add( HeaderNames.ContentType, "application/pdf" );
await stream.CopyToAsync(Response.Body);
await Response.Body.FlushAsync();
}
My attempt works as:
public HttpResponseMessage GetFileFromPath2(string guid)
{
var response = new HttpResponseMessage();
MemoryStream memoryStream = new MemoryStream();
var path = "C:\test";
if (_fileHelper.ExtistFileFromPath(path, guid))
{
memoryStream = new MemoryStream(File.ReadAllBytes(Path.Combine(path, guid)));
response.StatusCode = HttpStatusCode.OK;
response.Content = new StreamContent(memoryStream);
response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") { FileName = guid };
response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
response.Headers.AcceptRanges.Add("bytes");
}
else
{
response.StatusCode = HttpStatusCode.NoContent;
response.Content = new StringContent("File not found");
}
return response;
}
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