Upload HtmlHelper Overview

The Telerik UI Upload HtmlHelper for ASP.NET MVC is a server-side wrapper for the Kendo UI Upload widget.

The Upload uses progressive enhancement to deliver the best possible uploading experience to users, without requiring extra developer effort.

The Upload is part of Telerik UI for ASP.NET MVC, a professional grade UI library with 100+ components for building modern and feature-rich applications. To try it out sign up for a free 30-day trial.

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• Demo page for the Upload

Initializing the Upload

The following example demonstrates how to define the Upload widget by using the Upload HtmlHelper.

@(Html.Kendo().Upload()
    .Name("files")
    .Async(a => a
        .Save("Save", "Upload")
        .Remove("Remove", "Upload")
        .AutoUpload(true)
    )
)

public IWebHostEnvironment WebHostEnvironment { get; set; }

public UploadController(IWebHostEnvironment webHostEnvironment)
{
    WebHostEnvironment = webHostEnvironment;
}

public async Task<ActionResult> Save(IEnumerable<IFormFile> files)
{
    // The Name of the Upload component is "files".
    if (files != null)
    {
        foreach (var file in files)
        {
            var fileContent = ContentDispositionHeaderValue.Parse(file.ContentDisposition);

            // Some browsers send file names with full path.
            // The sample is interested only in the file name.
            var fileName = Path.GetFileName(fileContent.FileName.ToString().Trim('"'));
            var physicalPath = Path.Combine(WebHostEnvironment.WebRootPath, "App_Data", fileName);

            using (var fileStream = new FileStream(physicalPath, FileMode.Create))
            {
                await file.CopyToAsync(fileStream);
            }
        }
    }

    // Return an empty string to signify success.
    return Content("");
}

public ActionResult Remove(string[] fileNames)
{
    // The parameter of the Remove action must be called "fileNames".

    if (fileNames != null)
    {
        foreach (var fullName in fileNames)
        {
            var fileName = Path.GetFileName(fullName);
            var physicalPath = Path.Combine(WebHostEnvironment.WebRootPath, "App_Data", fileName);

            // TODO: Verify user permissions.

            if (System.IO.File.Exists(physicalPath))
            {
                System.     IO.File.Delete(physicalPath);
            }
        }
    }

    // Return an empty string to signify success.
    return Content("");
}

Basic Configuration

The following example demonstrates the basic configuration of the Upload HtmlHelper and how to get the Upload widget instance.

An Upload widget configured in such way offers support for multiple file selection, asynchronous removal of uploaded files, progress tracking, in-progress cancellation of upload, file drag-and-drop. Progress tracking, file drag-and-drop, and in-progress cancellation of upload are automatically enabled if supported by the browser.

The Upload works in <input type="file" /> elements, so it is only able to upload files selected by the user, which exist in the file system. For uploading files generated with JavaScript on the fly, use another approach, e.g. an Ajax request.

@(Html.Kendo().Upload()
    .Name("files")
    .Multiple(true)
    .Async(a => a
        .Save("ChunkSave", "Upload")
        .Remove("Remove", "Upload")
        .AutoUpload(true)
        .ChunkSize(1100)
    )
)

<script type="text/javascript">
    $(function() {
        // The Name() of the Upload is used to get its client-side instance.
        var files = $("#files").data("kendoUpload");
    });
</script>

Functionality and Features

• Modes of operation
• Dragging and dropping of files
• Chunk upload of files
• Validation of files
• Identification of files
• Sending and receiving metadata
• Accessibility

Events

The following example demonstrates Upload HTML helper exposes several events, which could be handled on the client-side. For a complete example on basic Upload events, refer to the demo on using the events of the Upload.

@(Html.Kendo().Upload()
    .Name("files")
    .Async(a => a
        .Save("Save", "Upload")
        .Remove("Remove", "Upload")
        .AutoUpload(true)
    )
    .Events(events => events
        .Cancel("onCancel")
        .Complete("onComplete")
        .Error("onError")
        .Progress("onProgress")
        .Remove("onRemove")
        .Select("onSelect")
        .Success("onSuccess")
        .Upload("onUpload")
    )
)

<script type="text/javascript">
    function onSelect(e) {
        console.log("Select :: " + getFileInfo(e));
    }

    function onUpload(e) {
        console.log("Upload :: " + getFileInfo(e));
    }

    function onSuccess(e) {
        console.log("Success (" + e.operation + ") :: " + getFileInfo(e));
    }

    function onError(e) {
        console.log("Error (" + e.operation + ") :: " + getFileInfo(e));
    }

    function onComplete(e) {
        console.log("Complete");
    }

    function onCancel(e) {
        console.log("Cancel :: " + getFileInfo(e));
    }

    function onRemove(e) {
        console.log("Remove :: " + getFileInfo(e));
    }

    function onProgress(e) {
        console.log("Upload progress :: " + e.percentComplete + "% :: " + getFileInfo(e));
    }

    function getFileInfo(e) {
        return $.map(e.files, function(file) {
            var info = file.name;

            // File size is not available in all browsers.
            if (file.size > 0) {
                info  += " (" + Math.ceil(file.size / 1024) + " KB)";
            }
            return info;
        }).join(", ");
    }
</script>

See Also

• Basic Usage by the Upload HtmlHelper for ASP.NET MVC (Demo)
• Using the API of the Upload HtmlHelper for ASP.NET MVC (Demo)
• Server-Side API