FileUploadStartEventArgs.Cancel Property

Specifies whether the file upload operation should be canceled.

Namespace: DevExpress.Blazor

Assembly: DevExpress.Blazor.v23.2.dll

NuGet Package: DevExpress.Blazor

Declaration

public bool Cancel { get; set; }

Property Value

Type	Description
Boolean	true to cancel file upload; otherwise, false.

Remarks

Handle the FileUploadStart event to control file upload before it is started. Use the event argument’s FileInfo property to get information about the file (its name, type, size, and so on). Set the event argument’s Cancel property to true to cancel file upload.

The following snippet prohibits upload of files whose size exceeds 1MB.

Razor

<DxUpload Name="myFile" UploadUrl="https://localhost:10000/api/Upload/Upload/" 
          FileUploadStart="@OnFileUploadStart">
</DxUpload>

@code {
    void OnFileUploadStart(FileUploadStartEventArgs e) {
        if (e.FileInfo.Size > 1048576)
            e.Cancel = true;
    }
}

UploadController

using System.IO;
using System.Linq;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;

[Route("api/[controller]")]
public class UploadController : ControllerBase {
    private readonly IWebHostEnvironment _hostingEnvironment;

    public UploadController(IWebHostEnvironment hostingEnvironment) {
        _hostingEnvironment = hostingEnvironment;
    }

    [HttpPost]
    [Route("UploadFile")]
    public ActionResult UploadFile(IFormFile myFile) {
        try {
            var path = Path.Combine(_hostingEnvironment.WebRootPath, "uploads");
            if (!Directory.Exists(path))
                Directory.CreateDirectory(path);
            using (var fileStream = System.IO.File.Create(Path.Combine(path, myFile.FileName))) {
                myFile.CopyTo(fileStream);
            }
        } catch {
            Response.StatusCode = 400;
        }

        return new EmptyResult();
    }
}