Скачать или смотреть How to Display Content of a .txt File in Blazor WebAssembly

Learn how to easily read and display the content of a `.txt` file in your Blazor WebAssembly application with this step-by-step guide.
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This video is based on the question https://stackoverflow.com/q/70033426/ asked by the user 'Szymon Jagaczewski' ( https://stackoverflow.com/u/14985273/ ) and on the answer https://stackoverflow.com/a/70033915/ provided by the user 'MrC aka Shaun Curtis' ( https://stackoverflow.com/u/13065781/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Display Content of a .txt File in Blazor WebAssembly

Are you working on a Blazor WebAssembly app and need to display the contents of a .txt file? Perhaps you’re using the InputFile component to allow users to upload files from their computer, but something isn't working as expected. This guide will guide you through the necessary steps to successfully read a .txt file and display its content in your Blazor application.

Understanding the Problem

When you try to load and display the content of a .txt file using the InputFile component in Blazor, you might face issues like not being able to read the file or having an empty output. This could be due to how the file stream is being read or how you handle the input change event.

Solution: Step-by-Step Guide

Here’s a corrected version of the initial code you shared, along with detailed explanations of what each part does:

1. Set Up the Input File Control

You’ll begin by creating a simple layout with an InputFile control, which lets users select a file from their devices.

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

-page "/": Defines the route for this component.

<InputFile>: This component is crucial as it allows users to choose a file. The OnChange attribute specifies the method to call when a file is selected.

2. Define the Code Behind the Component

In this section, you will process the file selection, read the content, and store it in a variable to display later.

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

private string fileContent = "";: This variable holds the content of the file that will be displayed in the UI.

private async Task OnInputFileChanged(...): This method handles the file change event. It reads the file’s content and converts it into a string format for display.

await file.OpenReadStream(maxsize).ReadAsync(buffer);: Opens a stream to read up to 500KB of the file. Ensure to handle file size properly to prevent issues when users upload large files.

3. Displaying the File Content

The <pre>-fileContent</pre> tag allows the plain text from the file to be displayed in the Blazor app. The <pre> tag maintains formatting such as line breaks and spaces.

Conclusion

With these adjustments, your Blazor WebAssembly app should now correctly handle the uploading and displaying of .txt file contents. This is a great feature that enhances user interactivity in your applications.

Further Enhancements

Consider adding error handling for unsupported file formats or file sizes.

You can also provide a progress indicator while the file is being read, especially for larger files.

By following this guide, you can confidently implement file reading in your Blazor applications. Happy coding!