FileUpload

in namespace DotVVM.BusinessPack.Controls

Renders a FileUpload control supporting HTML 5 upload features (drag & drop, directory upload, image previews, etc.).

Usage & Scenarios

Allows the user to upload one or multiple files asynchronously.

Upload Configuration

The upload works on the background and starts immediately when the user selects the files. To make file uploading work, you have to specify where the temporary files will be uploaded.

The recommended strategy is to store the uploaded files in your application directory or in the temp directory (if your app have the appropriate permissions). To define this, you have to register the UploadedFileStorage in your Startup.cs file.

// OWIN
app.UseDotVVM<DotvvmStartup>(appPath, options: o => o.AddUploadedFileStorage("App_Data/Temp"));

// ASP.NET Core
services.AddDotVVM(o => o.AddUploadedFileStorage("App_Data/Temp"));

Using the Control

Then, you need to bind the FileUpload control to an UploadData object. It holds references to the files the user has selected and uploaded.

It has a handy property IsBusy of boolean which indicates whether the file upload is still in progress. You can use it e.g. on the button's Enabled property to disallow the user to continue until the upload is finished.

Retrieving the Stored Files

The UploadData object holds only unique IDs of uploaded files. To get the file, you have to retrieve it using the UploadedFileStorage object.

foreach (var file in UploadData.Files)
{
  if (file.Allowed)
  {
    // get the stream of the uploaded file and do whatever you need to do
    var stream = storage.GetFile(file.FileId);

    // OR you can just move the file from the temporary storage somewhere else
    var targetPath = Path.Combine(uploadPath, file.FileId + ".bin");
    storage.SaveAs(file.FileId, targetPath);
    
    // it is a good idea to delete the file from the temporary storage 
    // it is not required, the file would be deleted automatically after the timeout set in the DotvvmStartup.cs
    storage.DeleteFile(file.FileId);
  }
}

A file is not Allowed when it's type does not match the AllowedFileTypes definition or when it's size exceeds the MaxFileSize. See also the FileTypeAllowed and MaxSizeExceeded properties. You can use them to find out why the file is not allowed. But please note that these value are sent from client-side and can't be trusted in security critical scenarios.

Sample 1: Basic Usage

The FileUpload control has the Data property (of type UploadData). Each file will get a unique ID which is stored in this collection.

The AllowMultipleFiles property specifies whether the user can select multiple files in the file browser window. It also enables directory upload in moder browsers.

page.dothtml
ViewModel.cs

<bp:FileUpload Data="{value: Upload}" 
               AllowMultipleFiles="true" />

using System.Collections.Generic;
using DotVVM.BusinessPack.Controls;
using DotVVM.Framework.ViewModel;

namespace DotvvmWeb.Views.Docs.Controls.businesspack.FileUpload.sample1
{
    public class ViewModel : DotvvmViewModelBase
    {
        public UploadData Upload { get; set; } = new UploadData();
    }
}

Sample 2: UploadCompleted Event

The UploadCompleted event is fired automatically when file is uploaded.

page.dothtml
ViewModel.cs

<bp:FileUpload Data="{value: Upload}"
               UploadCompleted="{command: ProcessFile()}" />

{{value: Message}}

using System.Collections.Generic;
using DotVVM.BusinessPack.Controls;
using DotVVM.Framework.ViewModel;

namespace DotvvmWeb.Views.Docs.Controls.businesspack.FileUpload.sample2
{
    public class ViewModel : DotvvmViewModelBase
    {
        public string Message { get; set; }

        public UploadData Upload { get; set; } = new UploadData();

        public void ProcessFile()
        {
            // do what you have to do with the uploaded files
            Message = "ProcessFile() was called.";
        }
    }
}

Sample 3: Processing the Files

You can use the Upload.IsBusy property to determine whether the upload is still in progress or not.

page.dothtml
ViewModel.cs

<bp:FileUpload Data="{value: Upload}" />

<p>
  <bp:Button Text="Save Files" 
              Click="{command: Process()}"
              Enabled="{value: !Files.IsBusy}" />
</p>

using System.IO;
using DotVVM.BusinessPack.Controls;
using DotVVM.Framework.Storage;
using DotVVM.Framework.ViewModel;

namespace DotvvmWeb.Views.Docs.Controls.businesspack.FileUpload.sample3
{
    public class ViewModel : DotvvmViewModelBase
    {
        private readonly IUploadedFileStorage fileStorage;

        public ViewModel(IUploadedFileStorage fileStorage)
        {
            this.fileStorage = fileStorage;
        }

        public UploadData Upload { get; set; } = new UploadData();

        public void Process()
        {
            var folderPath = GetFolderdPath();

            // save all files to disk
            foreach (var file in Upload.Files)
            {
                var filePath = Path.Combine(folderPath, file.FileId + ".bin");
                fileStorage.SaveAs(file.FileId, filePath);
                fileStorage.DeleteFile(file.FileId);
            }

            // clear the data so the user can continue with other files
            Upload.Clear();
        }

        private string GetFolderdPath()
        {
            var folderPath = Path.Combine(Context.Configuration.ApplicationPhysicalPath, "MyFiles");

            if (!Directory.Exists(folderPath))
            {
                Directory.CreateDirectory(folderPath);
            }

            return folderPath;
        }
    }
}

Sample 4: Drag & Drop Upload

The drag & drop upload is supported out-of-the-box. And if you need to customize its look and feel, you can use the DropTemplate property. It allows you to specify contents visible when user drags files over the FileUpload control.

The DropTemplate is by default rendered over all contents of the control. If you want to open an upload dialog after an element is clicked on, mark it with bp-select-files CSS class.

page.dothtml
ViewModel.cs

<bp:FileUpload Data="{value: Upload}">
    <DropTemplate>
        Drop files here!
    </DropTemplate>
    <!-- build a custom UI here -->
    <dot:Repeater DataSource="{value: Upload.Files}">
        <div>
            {{value: FileName}}
        </div>
    </dot:Repeater>
    <bp:Button class="bp-select-files" Text="Upload" /> 
</bp:FileUpload>

using System.Collections.Generic;
using DotVVM.BusinessPack.Controls;
using DotVVM.Framework.ViewModel;


namespace DotvvmWeb.Views.Docs.Controls.businesspack.FileUpload.sample4
{
    public class ViewModel : DotvvmViewModelBase
    {
        public UploadData Upload { get; set; } = new UploadData();
    }
}

Properties

Name	Type	Description	Notes	Default Value
AllowedFileTypes	String	Gets or sets the types of files that the server accepts. It must be a comma-separated list of unique content type specifiers (eg. ".jpg,image/png,audio/*").	attribute inner element static value bindable default	null
AllowMultipleFiles	Boolean	Gets or sets whether the user can select multiple files at once. It is enabled by default.	attribute inner element static value bindable default	True
Attributes	Dictionary<String,Object>		attribute inner element static value bindable default	null
ClientIDMode	ClientIDMode	Gets or sets the client ID generation algorithm.	attribute inner element static value bindable default	Static
Data	UploadData	Gets or sets the file upload data (e.g. list of uploaded files, upload progress).	attribute inner element static value bindable default	null
DataContext	Object	Gets or sets a data context for the control and its children. All value and command bindings are evaluated in context of this value.	attribute inner element static value bindable default	null
DeleteIconCssClass	String	Gets or sets the CSS class for the icon displayed on the button used to delete uploaded files. The default value is FaRemove.	attribute inner element static value bindable default	fa fa-remove
DragFilesHereText	String	Gets or sets the text informing about drag&drop upload; usually display next to the upload button. The default value is "or drag them here.".	attribute inner element static value bindable default	or drag them here.
DropTemplate	ITemplate	Gets or sets the template displayed when files are dragged over the control.	attribute inner element static value bindable default	null
Enabled	Boolean	Gets or sets a value indicating whether the control is enabled and can be modified.	attribute inner element static value bindable default	True
GenericErrorText	String	Gets or sets the text displayed when a generic / unknown error occurs. The default value is "Upload has failed.".	attribute inner element static value bindable default	Upload has failed.
ID	String	Gets or sets the unique control ID.	attribute inner element static value bindable default	null
InnerText	String	Gets or sets the inner text of the HTML element.	attribute inner element static value bindable default	null
MaxFileSize	Int32?	Gets or sets the maximum size of files in megabytes (MB). The size is not limited by default.	attribute inner element static value bindable default	null
UploadButtonText	String	Gets or sets the text on the upload button. The default value is "Select files".	attribute inner element static value bindable default	Select files
Visible	Boolean	Gets or sets whether the control is visible.	attribute inner element static value bindable default	True

Events

	Name	Type	Description
	UploadCompleted	Command	Gets or sets a command that is triggered when the upload is complete.