Getting Started with Blazor File Upload Component in Web App

16 Feb 20249 minutes to read

This section briefly explains about how to include Blazor File Upload component in your Blazor Web App using Visual Studio.

Prerequisites

System requirements for Blazor components

Create a new Blazor Web App

You can create a Blazor Web App using Visual Studio 2022 via Microsoft Templates or the Syncfusion Blazor Extension.

You need to configure the corresponding Interactive render mode and Interactivity location while creating a Blazor Web Application.

Install Syncfusion Blazor Inputs and Themes NuGet in the Blazor Web App

To add Blazor File Upload component in the app, open the NuGet package manager in Visual Studio (Tools → NuGet Package Manager → Manage NuGet Packages for Solution), search and install Syncfusion.Blazor.Inputs and Syncfusion.Blazor.Themes.

If you utilize WebAssembly or Auto render modes in the Blazor Web App need to be install Syncfusion Blazor components NuGet packages within the client project.

Alternatively, you can utilize the following package manager command to achieve the same.

Package Manager
Install-Package Syncfusion.Blazor.Inputs -Version 25.1.35
Install-Package Syncfusion.Blazor.Themes -Version 25.1.35

NOTE

Syncfusion Blazor components are available in nuget.org. Refer to NuGet packages topic for available NuGet packages list with component details.

Register Syncfusion Blazor Service

Open ~/_Imports.razor file and import the Syncfusion.Blazor and Syncfusion.Blazor.Inputs namespace.

@using Syncfusion.Blazor
@using Syncfusion.Blazor.Inputs

Now, register the Syncfusion Blazor Service in the ~/Program.cs file of your Blazor Web App. For a app with WebAssembly or Auto (Server and WebAssembly) interactive render mode, register the Syncfusion Blazor service in both ~/Program.cs files of your web app.

....
using Syncfusion.Blazor;
....
builder.Services.AddSyncfusionBlazor();
....

Add stylesheet and script resources

The theme stylesheet and script can be accessed from NuGet through Static Web Assets. Include the stylesheet reference in the <head> section and the script reference at the end of the <body> in the ~/Components/App.razor file as shown below:

<head>
    ....
    <link href="_content/Syncfusion.Blazor.Themes/bootstrap5.css" rel="stylesheet" />
</head>
....
<body>
    ....
    <script src="_content/Syncfusion.Blazor.Core/scripts/syncfusion-blazor.min.js" type="text/javascript"></script>
</body>

NOTE

Check out the Blazor Themes topic to discover various methods (Static Web Assets, CDN, and CRG) for referencing themes in your Blazor application. Also, check out the Adding Script Reference topic to learn different approaches for adding script references in your Blazor application.

Add Syncfusion Blazor File Upload component

Add the Syncfusion Blazor File Upload component in .razor file inside the Pages folder. If an interactivity location as Per page/component in the web app, define a render mode at top of the component, as follows:

RAZOR

@* desired render mode define here *@
@rendermode InteractiveAuto

RAZOR

<SfUploader></SfUploader>

Press Ctrl+F5 (Windows) or ⌘+F5 (macOS) to launch the application. This will render the Syncfusion Blazor File Upload component in your default web browser.

Without server-side API endpoint

You can upload the files and files of folders in the Blazor application without specifying the server-side API end point using AsyncSettings.

Save and Remove actions

You can get the uploaded files as file stream in the ValueChange event argument. Now, you can write the save handler inside ValueChange event to save the files to desired location. Find the save action code below.

RAZOR
@using Syncfusion.Blazor.Inputs
<SfUploader AutoUpload="true">
      <UploaderEvents ValueChange="@OnChange"></UploaderEvents>
</SfUploader>
@code {
    private async Task OnChange(UploadChangeEventArgs args)
    {
        try
        {
            foreach (var file in args.Files)
            {
                var path = @"" + file.FileInfo.Name;
                FileStream filestream = new FileStream(path, FileMode.Create, FileAccess.Write);
                await file.File.OpenReadStream(long.MaxValue).CopyToAsync(filestream);
                filestream.Close();
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
        }
    }
}

Blazor FileUpload displays Updated Files

While clicking on the remove icon in the file list, you will get the OnRemove event with removing file name as argument. So, you can write the remove handler inside OnRemove event to remove the particular file from desired location. Find the remove action code below.

CSHTML

Private void onRemove(RemovingEventArgs args)
{
    foreach(var removeFile in args.FilesData)
    {
        if (File.Exists(Path.Combine(@"rootPath", removeFile.Name)))
        {
            File.Delete(Path.Combine(@"rootPath", removeFile.Name))
        }
    }
}

With server-side API endpoint

The upload process requires save and remove action URL to manage the upload process in the server.

NOTE

The save action is necessary to handle the upload operation.

* The remove action is optional, one can handle the removed files from server.

The save action handler upload the files that needs to be specified in the SaveUrl property.

The save handler receives the submitted files and manages the save process in server. After uploading the files to server location, the color of the selected file name changes to green and the remove icon is changed as bin icon.

The remove action is optional. The remove action handler removes the files that needs to be specified in the RemoveUrl property. OnActionComplete event triggers after all the selected files have been processed to upload successfully or failed to server.

CSHTML
[Route("api/[controller]")]

private IHostingEnvironment hostingEnv;

public SampleDataController(IHostingEnvironment env)
{
    this.hostingEnv = env;
}

[HttpPost("[action]")]
public void Save(IList<IFormFile> UploadFiles)
{
    try
    {
        foreach (var file in UploadFiles)
        {
            var filename = hostingEnv.ContentRootPath + $@"\{file.FileName}";
            if (!System.IO.File.Exists(filename))
            {
                using (FileStream fs = System.IO.File.Create(filename))
                {
                    file.CopyTo(fs);
                    fs.Flush();
                }
            }
        }
    }
    catch (Exception e)
    {
        Response.Clear();
        Response.StatusCode = 204;
        Response.HttpContext.Features.Get<IHttpResponseFeature>().ReasonPhrase = "File failed to upload";
        Response.HttpContext.Features.Get<IHttpResponseFeature>().ReasonPhrase = e.Message;
    }
}

[HttpPost("[action]")]
public void Remove(IList<IFormFile> UploadFiles)
{
    try
    {
        var filename = hostingEnv.ContentRootPath + $@"\{UploadFiles[0].FileName}";
        if (System.IO.File.Exists(filename))
        {
            System.IO.File.Delete(filename);
        }
    }
    catch (Exception e)
    {
        Response.Clear();
        Response.StatusCode = 200;
        Response.HttpContext.Features.Get<IHttpResponseFeature>().ReasonPhrase = "File removed successfully";
        Response.HttpContext.Features.Get<IHttpResponseFeature>().ReasonPhrase = e.Message;
    }
}

The OnFailure event is triggered when there is a failure in the AJAX request during the uploading or removing of files. It provides a way to handle and respond to any errors or issues that occur during the file upload or removal process.

RAZOR
<SfUploader ID="UploadFiles">
    <UploaderAsyncSettings SaveUrl="api/SampleData/Save" RemoveUrl="api/SampleData/Remove"></UploaderAsyncSettings>
    <UploaderEvents OnFailure="@OnFailureHandler" OnActionComplete="@OnActionCompleteHandler"></UploaderEvents>
</SfUploader>
@code {
    private void OnFailureHandler(FailureEventArgs args)
    {
        // Here, you can customize your code.
    }
    private void OnActionCompleteHandler(ActionCompleteEventArgs args)
    {
        // Here, you can customize your code.
    }
}

Configure allowed file types

You can allow the specific files alone to upload using the AllowedExtensions property. The extension can be represented as collection by comma separators. The uploader component filters the selected or dropped files to match against the specified file types and processes the upload operation. The validation happens when you specify value to inline attribute to accept the original input element.

RAZOR
<SfUploader AllowedExtensions=".doc, .docx, .xls, .xlsx"></SfUploader>

Allowing Specific Files in Blazor FileUpload

NOTE

View Sample in GitHub.