the file uploaded in chuncks is incomplete
Hi..
I have a issue with the fle upload in chuncks..
the file is uploaded incomplete
the code is this
@page "/"
@using Syncfusion.Blazor.DropDowns
@using Syncfusion.Blazor.Inputs
<SfUploader ID="UploadFiles">
<UploaderAsyncSettings SaveUrl="api/SampleData/Save" RemoveUrl="api/SampleData/Remove" ChunkSize="500000"></UploaderAsyncSettings>
<UploaderEvents OnChunkUploadStart="@OnChunkUploadStartHandler" OnChunkSuccess="@OnChunkSuccessHandler" Success="@SuccessHandler" OnChunkFailure="@OnChunkFailureHandler"></UploaderEvents>
</SfUploader>
@code {
private void SelectedHandler(SelectedEventArgs args)
{
args.CustomFormData = new List<object> { new { Name = "Syncfusion" } };
var accessToken = "Authorization_token";
args.CurrentRequest = new List<object> { new { Authorization = accessToken } };
}
private void OnChunkUploadStartHandler(UploadingEventArgs args)
{
args.CustomFormData = new List<object> { new { Name = "Syncfusion" } };
var accessToken = "Authorization_token";
args.CurrentRequest = new List<object> { new { Authorization = accessToken } };
}
private void OnChunkSuccessHandler(SuccessEventArgs args)
{
// Here, you can customize your code.
}
private void SuccessHandler(SuccessEventArgs args)
{
// Here, you can customize your code.
}
private void OnChunkFailureHandler(FailureEventArgs args)
{
// Here, you can customize your code.
}
}
and the controller is
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.FileProviders;
namespace BlazorUploadAndDownload.Data
{
[Route("api/[controller]")]
public class SampleDataController : Controller
{
public string uploads = ".\\Uplo"; // replace with your directory path
[HttpPost("[action]")]
public async Task<IActionResult> Save(IFormFile UploadFiles) // Save the uploaded file here
{
if (UploadFiles.Length > 0)
{
var filePath = Path.Combine(uploads, UploadFiles.FileName);
if (System.IO.File.Exists(filePath))
{
//Return custom-error if file already exists
Response.Headers.Append("custom-error", "File already exists.");
//Return conflict status code
// return new StatusCodeResult(StatusCodes.Status409Conflict);
}
using (var fileStream = new FileStream(filePath, FileMode.Create))
{
//Save the uploaded file to server
await UploadFiles.CopyToAsync(fileStream);
}
}
//Return success response
Response.Headers.Append("success", "File saved successfully.");
return Ok();
}
[HttpPost("[action]")]
public void Remove(string UploadFiles) // Delete the uploaded file here
{
if (UploadFiles != null)
{
var filePath = Path.Combine(uploads, UploadFiles);
if (System.IO.File.Exists(filePath))
{
//Delete the file from server
System.IO.File.Delete(filePath);
}
}
}
[HttpGet("[action]")]
public FileResult Download(string filename)
{
var filePath = Path.Combine(Directory.GetCurrentDirectory() + "\\Uplo");
IFileProvider provider = new PhysicalFileProvider(filePath);
IFileInfo fileInfo = provider.GetFileInfo(filename);
var readStream = fileInfo.CreateReadStream();
var mimeType = "application/pdf";
return File(readStream, mimeType, filename);
}
public IActionResult Index()
{
return View();
}
}
}
Attachment: uploadfile_37eec646.zip
Hi Facuna,
You’re seeing an “incomplete file” because your Save action always writes with FileMode.Create and assumes a full file arrives in a single request. With chunk upload enabled, each request contains only a slice of the file. You must detect chunk Index/total Chunk on the server and append the chunk until the last one arrives, then finalize the file.
You need to:
- Detect chunk metadata (chunk index, total chunks, file name).
- Append chunks to the file instead of recreating it.
- Finalize the file when all chunks are uploaded.
Here’s an example of how to handle chunked uploads:
[HttpPost("[action]")] public async Task<IActionResult> Save(IFormFile UploadFiles) { try { if (UploadFiles.Length > 0) { var fileName = UploadFiles.FileName; // Create upload directory if it doesn't exist if (!Directory.Exists(uploads)) { Directory.CreateDirectory(uploads); } if (UploadFiles.ContentType == "application/octet-stream") //Handle chunk upload { // Fetch chunk-index and total-chunk from form data var chunkIndex = Request.Form["chunk-index"]; var totalChunk = Request.Form["total-chunk"]; // Path to save the chunk files with .part extension var tempFilePath = Path.Combine(uploads, fileName + ".part"); using (var fileStream = new FileStream(tempFilePath, chunkIndex == "0" ? FileMode.Create : FileMode.Append)) { await UploadFiles.CopyToAsync(fileStream); } // If all chunks are uploaded, move the file to the final destination if (Convert.ToInt32(chunkIndex) == Convert.ToInt32(totalChunk) - 1) { var finalFilePath = Path.Combine(uploads, fileName); // Move the .part file to the final destination without the .part extension System.IO.File.Move(tempFilePath, finalFilePath); return Ok(new { status = "File uploaded successfully" }); } return Ok(new { status = "Chunk uploaded successfully" }); } else //Handle normal upload { var filePath = Path.Combine(uploads, fileName); using (var fileStream = new FileStream(filePath, FileMode.Create)) { await UploadFiles.CopyToAsync(fileStream); } return Ok(new { status = "File uploaded successfully" }); } } return BadRequest(new { status = "No file to upload" }); } catch (Exception ex) { return StatusCode(500, new { status = "Error", message = ex.Message }); } } |
This controller will correctly assemble chunked uploads and keep your non-chunked uploads working.
Documentation Link: https://blazor.syncfusion.com/documentation/file-upload/chunk-upload#cancel-upload
Regards,
Suresh
Attachment: BlazorUploaderSample_34907d3a.zip
- 1 Reply
- 2 Participants
-
FM Facuna Mx
- Dec 1, 2025 06:27 PM UTC
- Dec 3, 2025 05:25 AM UTC
