Скачать или смотреть How to Create and Download a File in Blazor WASM

Learn how to generate and download JSON files in `Blazor WASM` without extensive JavaScript knowledge. This guide covers everything you need to know about using file streams and JS Interop for seamless file downloads.
---
This video is based on the question https://stackoverflow.com/q/75072133/ asked by the user 'javirs' ( https://stackoverflow.com/u/1862413/ ) and on the answer https://stackoverflow.com/a/75074836/ provided by the user 'Axekan' ( https://stackoverflow.com/u/12519793/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: blazor WASM create and download a file

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Create and Download a File in Blazor WASM

Creating and downloading files in a web application can often pose a challenge, especially for developers new to front-end development. In Blazor WASM, one common requirement is allowing users to download JSON files generated from data in your application. If you're unsure where to start or lack JavaScript expertise, fear not! In this guide, we’ll explore a straightforward way to generate a JSON file in memory and provide it for download using Blazor's features along with a touch of JavaScript Interop.

Understanding the Problem

Imagine you have a C- class that holds data you need to share in a JSON format. The goal is to automate the process of generating a JSON representation of this data and offer it for download when a user clicks a button. While you might be tempted to dive deep into JavaScript, we’ll explore a solution that primarily leverages Blazor functionalities, employing minimal JavaScript.

Solution Overview

To achieve this functionality in Blazor, we will:

Serialize the object to JSON.

Create a memory stream from the serialized data.

Use JavaScript Interop to handle the actual download process in the browser.

Step 1: Set Up the Blazor Component

First, we need to ensure that we can serialize our object to JSON and create a memory stream that will hold this JSON data.

Here’s how you can implement it in your Blazor component:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the Blazor Code

Serialization: This takes the objectToSave and converts it into a JSON string using JsonSerializer.Serialize.

MemoryStream Creation: A MemoryStream is created to hold the byte representation of the JSON string.

JS Interop: We call the JavaScript function downloadFileFromStream, passing it the file name and a reference to our memory stream.

Step 2: Implementing the JavaScript Function

In your JavaScript, you will need to handle the downloading process. Add the following function to your wwwroot/index.html or a separate JavaScript file:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the JavaScript Code

Blob Creation: A Blob is created from the ArrayBuffer received from the stream.

Download Link Setup: An anchor (<a>) element is created programmatically to facilitate the file download.

Cleanup: After triggering the download, the object URL is revoked to free up resources.

Conclusion

With this simple setup, users can now download JSON files generated from your Blazor WASM application without the need for extensive JavaScript knowledge. By using Blazor’s built-in capabilities alongside minimal JavaScript, the process becomes straightforward and efficient.

Whether you’re compiling user data, application configurations, or other information, this method provides a seamless experience for providing downloadable content from your web application. So, take heart in building this functionality and enhance your Blazor applications with ease!