I'm attempting to return an image from a server route, but I'm getting one that is 0 bytes. I suspect it has something to do with how I'm using the MemoryStream. Here's my code:
[HttpGet]
[Route("edit")]
public async Task<HttpResponseMessage> Edit(int pdfFileId)
{
var pdf = await PdfFileModel.PdfDbOps.QueryAsync((p => p.Id == pdfFileId));
IEnumerable<Image> pdfPagesAsImages = PdfOperations.PdfToImages(pdf.Data, 500);
MemoryStream imageMemoryStream = new MemoryStream();
pdfPagesAsImages.First().Save(imageMemoryStream, ImageFormat.Png);
HttpResponseMessage response = new HttpResponseMessage();
response.Content = new StreamContent(imageMemoryStream);
response.Content.Headers.ContentType = new MediaTypeHeaderValue("image/png");
response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
{
FileName = pdf.Filename,
DispositionType = "attachment"
};
return response;
}
Through debugging I have verified that the PdfToImages method is working and that imageMemoryStream gets filled with data from the line
pdfPagesAsImages.First().Save(imageMemoryStream, ImageFormat.Png);
However in running it, I receive an attachment that is properly named but is 0 bytes. What do I need to change in order to receive the whole file? I think it's something simple but I'm not sure what. Thanks in advance.
After writing to the MemoryStream, Flush it then set Position to 0:
imageMemoryStream.Flush();
imageMemoryStream.Position = 0;
You should rewind MemoryStream to beginning before passing it to response. But you'd better use PushStreamContent:
HttpResponseMessage response = new HttpResponseMessage();
response.Content = new PushStreamContent(async (stream, content, context) =>
{
var pdf = await PdfFileModel.PdfDbOps.QueryAsync(p => p.Id == pdfFileId);
content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
{
FileName = pdf.Filename,
DispositionType = "attachment"
};
PdfOperations.PdfToImages(pdf.Data, 500).First().Save(stream, ImageFormat.Png);
}, "image/png");
return response;
Related
I have one memory stream object in my server-side, this object should be accessible in another party, which I call it a client or a consumer for my API.
In server-side I have a method like this (parameters.Save is related to a third-party library)
public MemoryStream GetSerializedParameters()
{
var parameters = GetParameters();
MemoryStream memory = new MemoryStream();
parameters.Save(memory);
return memory;
}
I'm thinking about sending this memory stream to a client with web API, so my action is something like this:
[HttpGet("parameters")]
public HttpResponseMessage GetParameters()
{
var stream = _server.GetSerializedParameters();
HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
result.Content = new StreamContent(stream);
result.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/octet-stream");
result.Content.Headers.ContentLength = stream.Length;
return result;
}
I'm not sure if it is the right way and this implementation is correct because I am in trouble to consume it:
I do not know which method of httpClient I have to use: ReadAsStreamAsync() or anything else, because I could not find anything to work
Sure you can:
[HttpGet]
public async Task Get()
{
var randomString = "thisIsCool";
var randomStringBytes = Encoding.UTF8.GetBytes(randomString);
using (var ms = new MemoryStream(randomStringBytes))
{
await ms.CopyToAsync(this.Response.Body);
}
Based on my under standing below code may help you:
WEB API:
[HttpGet]
public HttpResponseMessage ReadToStream(HttpRequestMessage requestMessage)
{
var streamObj = _server.GetSerializedParameters();
HttpResponseMessage response = new HttpResponseMessage();
response.Content = new StreamContent(streamObj);
requestMessage.RegisterForDispose(streamObj);
response.StatusCode = HttpStatusCode.OK;
return response;
}
Client Side
public async Task<string> DownloadFile(string guid)
{
var fileInfo = new FileInfo($"{guid}.txt");
var response = await _httpClient.GetAsync($"{url}/api/fileDownloadAPI?guid={guid}");
response.EnsureSuccessStatusCode();
await using var ms = await response.Content.ReadAsStreamAsync();
await using var fs = File.Create(fileInfo.FullName);
ms.Seek(0, SeekOrigin.Begin);
ms.CopyTo(fs);
return fileInfo.FullName;
}
I found the solution like this:
here is in server side:
[HttpGet("parameters")]
public IActionResult GetParameters()
{
var stream = _server.GetSerializedParameters();
stream.Seek(0, SeekOrigin.Begin);
return File(stream, MediaTypeNames.Text.Plain, "parameters.txt");
}
and here is in client-side:
public MemoryStream StoreParameters()
{
var request =new HttpRequestMessage
{
RequestUri = new Uri("https://localhost:44316/api/parameters"),
Method = HttpMethod.Get
};
request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
var result = _httpClient.SendAsync(request, HttpCompletionOption.ResponseHeadersRead).Result;
var ms = new MemoryStream();
result.Content.CopyToAsync(ms).Wait();
return result.IsSuccessStatusCode ? ms: null;
}
My ASP.NET Core app uses "out-of-box" external login authentication. What I want to implement - on facebook challenge I want to wrap redirect url and return it as json to consume in jquery frontend. But after request ends I see 500 error in browser and next error in application console:
fail: Microsoft.AspNetCore.Server.Kestrel[13]
Connection id "0HLV651D6KVJC", Request id "0HLV651D6KVJC:00000005": An unhandled exception was thrown by the
application. System.InvalidOperationException: Response Content-Length
mismatch: too few bytes written (0 of 470).
My external login action, nothing special to look at
[HttpPost]
[AllowAnonymous]
[ValidateAntiForgeryToken]
public IActionResult ExternalLogin(string provider, string returnUrl = null)
{
// Request a redirect to the external login provider.
var redirectUrl = Url.Action(nameof(ExternalLoginCallback), "Account", new { returnUrl });
var properties = _signInManager.ConfigureExternalAuthenticationProperties(provider, redirectUrl);
return Challenge(properties, provider);
}
Facebook authentication configuration:
services.AddAuthentication().AddFacebook(facebookOptions =>
{
facebookOptions.AppId = Configuration["Authentication:Facebook:AppId"];
facebookOptions.AppSecret = Configuration["Authentication:Facebook:AppSecret"];
facebookOptions.Events.OnRedirectToAuthorizationEndpoint =
async (x) =>
{
UTF8Encoding encoding = new UTF8Encoding();
var content = JsonConvert.SerializeObject(new { redirect_url = x.RedirectUri });
byte[] bytes = encoding.GetBytes(content);
x.Response.StatusCode = 200;
x.Response.ContentLength = bytes.Length;
x.Response.ContentType = "text/plain";
x.Response.Body = new MemoryStream();
await x.Response.WriteAsync(content);
// at this point I see that x.Response.Body.Length == 470, but message states there are 0 of 470 written
};
});
Is there any way I could make it work?
This can also happen when using new C# using syntax like this:
using var ms = new MemoryStream();
using var writer = new StreamWriter(ms);
writer.WriteLine("my content");
memoryStream.Position = 0;
return File(ms, "text/plain");
in this case, the MemoryStream is accessed before the StreamWriter is flushed. Either use old syntax for the StreamWriter:
using var ms = new MemoryStream();
using (var writer = new StreamWriter(ms, Encoding.UTF8, -1, true))
{
writer.WriteLine("my content");
}
memoryStream.Position = 0;
return File(ms, "text/plain");
or flush the writer:
using var ms = new MemoryStream();
using var writer = new StreamWriter(ms);
writer.WriteLine("my content");
writer.Flush();
memoryStream.Position = 0;
return File(ms, "text/plain");
Changed code to write to original response stream and it works now.
facebookOptions.Events.OnRedirectToAuthorizationEndpoint =
async (x) =>
{
var content = JsonConvert.SerializeObject(new { redirect_url = x.RedirectUri });
x.Response.StatusCode = 200;
x.Response.ContentType = "text/plain";
await x.Response.WriteAsync(content);
};
You can use something like this:
var stream = new MemoryStream();
/// writing to the stream
if (stream.CanSeek)
{
stream.Seek(0, SeekOrigin.Begin);
}
/// then read stream
i am trying to download a file (.docx) from asp.net web api.
Since i already have a document in the server i set the path to existing one and then i follow something sugested on stackoverflow and do this:
docDestination is my path.
HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
var stream = new FileStream(docDestination, FileMode.Open, FileAccess.Read);
result.Content = new StreamContent(stream);
result.Content.Headers.ContentType = new MediaTypeHeaderValue("application/vnd.openxmlformats-officedocument.wordprocessingml.document");
return result;
after that on my client side i try to do this:
.then(response => {
console.log("here lives the response:", response);
var headers = response.headers;
var blob = new Blob([response.body], { type: headers['application/vnd.openxmlformats-officedocument.wordprocessingml.document'] });
var link = document.createElement('a');
link.href = window.URL.createObjectURL(blob);
link.download = "Filename";
link.click();
}
this is what i get on my response
what i get:
any help?
Just add ContentDisposition to your response header with value of attachment and the browser will interpret it as a file that needs to be download
HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
var stream = new FileStream(docDestination, FileMode.Open,FileAccess.Read);
result.Content = new StreamContent(stream);
result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
{
FileName = "document.docx"
};
result.Content.Headers.ContentType = new MediaTypeHeaderValue("application/vnd.openxmlformats-officedocument.wordprocessingml.document");
return result;
Take a look in this link for more information in ContentDisposition header
Change return type of your method. You can write method something like this.
public FileResult TestDownload()
{
FileContentResult result = new FileContentResult(System.IO.File.ReadAllBytes("YOUR PATH TO DOC"), "application/msword")
{
FileDownloadName = "myFile.docx"
};
return result;
}
In client side, you just need to have a link button. Once you click on the button, file will be downloaded. Just write this line in cshtml file. replace controller name with your controller name.
#Html.ActionLink("Button 1", "TestDownload", "YourCOntroller")
When you have a stream open, you want to return it's content as a file
[HttpGet]
public async Task<FileStreamResult> Stream()
{
var stream = new MemoryStream(System.IO.File.ReadAllBytes("physical path of file"));
var response = File(stream, "Mime Type of file");
return response;
}
You use it when you have a byte array you would like to return as a file
[HttpGet]
public async Task<FileContentResult> Content()
{
var result = new FileContentResult(System.IO.File.ReadAllBytes("physical path of file"), "Mime Type of file")
{
FileDownloadName = "Your FileName"
};
return result;
}
when you have a file on disk and would like to return it's content (you give a path)-------------only in asp.net core
[HttpGet]
public async Task<IActionResult> PhysicalPath()
{
var result = new PhysicalFileResult("physical path of file", "Mime Type of file")
{
FileDownloadName = "Your FileName",
FileName = "physical path of file"
};
return result;
}
I just want to return a .csv file.
It works with the HttpResponseMessage but not with IHttpActionResult
Why?
WORKS
public async Task<HttpResponseMessage> ExportLeads()
{
byte[] bytes = new byte[2];
var result = new HttpResponseMessage(HttpStatusCode.OK) { Content = new ByteArrayContent(bytes) };
result.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") { FileName = "test.csv" };
return result;
}
DOES NOT WORK
public async Task<IHttpActionResult> ExportLeads()
{
byte[] bytes = new byte[2];
var result = new HttpResponseMessage(HttpStatusCode.OK) { Content = new ByteArrayContent(bytes) };
result.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") { FileName = "test.csv" };
return Content(HttpStatusCode.OK, result);
}
Error =>
The type "System.Net.Http.ByteArrayContent" can not be serialized.
Annotate it with the Attribut "DataContractAttribute"...
Content(HttpStatusCode.OK, result) will return a NegotiatedContentResult. As such you will need to set up a ContentNegotiator and Formatters to format the file contents. As you just want to return the raw CSV as a binary array in the content (as per your code returning HttpResponseMessage) then you should use the following:
return this.ResponseMessage(result)
I am using WebAPI for downloading a .pdf file like this:
[HttpGet]
public async Task<HttpResponseMessage> DownloadFile(string id, bool attachment = true)
{
HttpResponseMessage result = null;
try
{
MyService service = new MyService();
var bytes = await service.DownloadFileAsync(id);
if (bytes != null)
{
result = GetBinaryFile(personalDocument, string.Format("{0}.pdf", id), attachment);
}
else
{
result = new HttpResponseMessage(HttpStatusCode.NotFound);
}
}
catch (Exception ex)
{
throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.BadRequest) { ReasonPhrase = "ServerError" });
}
return result;
}
private HttpResponseMessage GetBinaryFile(byte[] bytes, string fileName, bool attachment)
{
HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
// result.Content = new ByteArrayContent(bytes);
result.Content = new StreamContent(new System.IO.MemoryStream(bytes));
//result.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
result.Content.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("inline");
if (attachment)
{
result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
}
result.Content.Headers.ContentDisposition.FileName = fileName;
result.Content.Headers.ContentLength = bytes.Length;
return result;
}
The issue is: when I download file for the first time it freezes the browser, and cannot perform anything. But after a refresh of the page, every time the file download is successful.
I tried to use ByteArrayContent or StreamContent but same thing happens. I also tried to use MediaTypeHeaderValue("application/octet-stream") or MediaTypeHeaderValue("application/pdf"), but again - the same issue occurred.
So I find that the problem is
if (attachment)
{
result.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");
}
If I set attachment to be true it set ContentDisposition to be ContentDispositionHeaderValue("attachment") (it is for download only)
If I set attachment to be false it open the file immediately and doesn't freeze the browser..
Any idea? Thanks!