I am exporting excel file using WebApi but it throws an exception and I don't know why. I googled it and haven't found any solution.
Exeption:
<Error>
<Message>An error has occurred.</Message>
<ExceptionMessage>Error while copying content to a stream.</ExceptionMessage>
<ExceptionType>System.Net.Http.HttpRequestException</ExceptionType>
<StackTrace>
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter.GetResult() at Microsoft.AspNet.WebApi.Extensions.Compression.Server.BaseServerCompressionHandler.<HandleCompression>d__17.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.ConfiguredTaskAwaitable`1.ConfiguredTaskAwaiter.GetResult() at Microsoft.AspNet.WebApi.Extensions.Compression.Server.BaseServerCompressionHandler.<SendAsync>d__15.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() at System.Web.Http.HttpServer.<SendAsync>d__0.MoveNext()
</StackTrace>
<InnerException>
<Message>An error has occurred.</Message>
<ExceptionMessage>Cannot access a closed Stream.</ExceptionMessage>
<ExceptionType>System.ObjectDisposedException</ExceptionType>
<StackTrace>
at System.IO.__Error.StreamIsClosed() at System.IO.MemoryStream.get_Position() at System.Net.Http.StreamToStreamCopy.StartAsync()
</StackTrace>
</InnerException>
</Error>
My Code is :
[AllowAnonymous]
[HttpGet]
[Route("api/AddPatient/ExportToExcel")]
public HttpResponseMessage ExportToExcel()
{
try
{
MemoryStream dataStream = Utility.GetFile();
HttpResponseMessage httpResponseMessage = Request.CreateResponse(HttpStatusCode.OK);
httpResponseMessage.Content = new StreamContent(dataStream);
httpResponseMessage.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
httpResponseMessage.Content.Headers.ContentDisposition.FileName = "Test.xlsx";
httpResponseMessage.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
return httpResponseMessage;
}
catch (Exception ex)
{
throw;
}
}
GetFile function as below for getting excel memorystream Note: using NPOI i am createting excel file
public static MemoryStream GetFile()
{
MemoryStream stream =null;
XSSFWorkbook wb = new XSSFWorkbook();
ISheet sheet = wb.CreateSheet("Test");
var row = sheet.CreateRow(0);
var cell = row.CreateCell(0);
cell.SetCellValue("Test");
using ( stream = new MemoryStream())
{
wb.Write(stream);
}
return stream;
}
You need to be careful when dealing with the stream object.
But I think your function to get dataStream
also wrong. More code perhaps?
try
{
using(MemoryStream dataStream = Utility.GetFile())
{
// read from beginning
dataStream.Position = 0;
HttpResponseMessage httpResponseMessage = Request.CreateResponse(HttpStatusCode.OK);
httpResponseMessage.Content = new StreamContent(dataStream);
httpResponseMessage.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
httpResponseMessage.Content.Headers.ContentDisposition.FileName = "Test.xlsx";
httpResponseMessage.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
return httpResponseMessage;
}
}
catch (Exception ex)
{
throw;
}
Your GetFile
cannot wrap using statement, that will close your memory stream object.
// try this
public static MemoryStream GetFile()
{
MemoryStream stream = new MemoryStream();
// do your thing
XSSFWorkbook wb = new XSSFWorkbook();
ISheet sheet = wb.CreateSheet("Test");
var row = sheet.CreateRow(0);
var cell = row.CreateCell(0);
cell.SetCellValue("Test");
wb.Write(stream);
// reset position here
stream.Position = 0;
return stream;
}
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