Angular tutorial: How to show a file browser to the user and load files into application memory

In this tutorial, we'll explore how to use the BrowserService from the TurboGUI library in an Angular application to load local files using the browseLocalFiles() method. This powerful feature allows users to select files from their local machine and load their contents directly into the browser memory, making them available for further processing in your application.

Prerequisites

Before we begin, make sure you have the following set up:

Node.js and npm installed on your machine
Angular CLI installed globally (npm install -g @angular/cli)
An existing Angular project or create a new one using ng new my-file-loader-app

Step 1: Installing TurboGUI

First, we need to install the TurboGUI library in our Angular application.

Navigate to your project directory in the terminal.
Install the TurboGUI library by running:

npm install turbogui-angular

Step 2: Creating a Component to Use the BrowserService

Let's create a component to demonstrate how to use the BrowserService to load local files.

Generate a new component using Angular CLI:

ng generate component file-loader

Open the generated file-loader.component.ts file and replace its contents with the following code:

import { Component } from '@angular/core';
import { BrowserService } from 'turbogui-angular';

@Component({
  selector: 'app-file-loader',
  templateUrl: './file-loader.component.html',
  styleUrls: ['./file-loader.component.css']
})
export class FileLoaderComponent {
  loadedFiles: { name: string, content: string }[] = [];

  constructor(private browserService: BrowserService) {}

  onFileSelected(event: any) {
    this.browserService.browseLocalFiles(event, 'TEXT', (fileNames, fileContents) => {
      this.loadedFiles = fileNames.map((name, index) => ({
        name,
        content: fileContents[index]
      }));
    });
  }
}

Update the file-loader.component.html file with the following content:

<h2>File Loader</h2>
<input type="file" multiple (change)="onFileSelected($event)" accept=".txt">
<div *ngFor="let file of loadedFiles">
  <h3>{{ file.name }}</h3>
  <pre>{{ file.content }}</pre>
</div>

Step 3: Using the FileLoaderComponent

Now that we have our FileLoaderComponent ready, let's use it in our main app component.

Open app.component.html and add the following line:

<app-file-loader></app-file-loader>

Make sure the FileLoaderComponent is declared in the app.module.ts file:

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import { FileLoaderComponent } from './file-loader/file-loader.component';
import { BrowserService } from 'turbogui-angular';

@NgModule({
  declarations: [AppComponent, FileLoaderComponent],
  imports: [BrowserModule],
  providers: [BrowserService],
  bootstrap: [AppComponent]
})
export class AppModule { }

Step 4: Running the Application

Now that everything is set up, let's run our application and test the file loading functionality.

Start the development server:

ng serve

Open your browser and navigate to http://localhost:4200.
You should see a file input on the page. Click on it and select one or more text files from your local machine.
After selecting the files, you'll see their names and contents displayed on the page.

How It Works

Let's break down the key parts of our implementation:

We're using the BrowserService directly from the TurboGUI library, which includes the browseLocalFiles() method.
In our FileLoaderComponent, we inject the BrowserService and use it in the onFileSelected() method.
The browseLocalFiles() method takes three arguments:
- event: The change event from the file input
- mode: We're using 'TEXT' to load the files as plain text
- callback: A function that receives the file names and contents
Inside the callback, we map the file names and contents to an array of objects, which we then display in the component's template.

Conclusion

In this tutorial, we've learned how to use the BrowserService from the TurboGUI library in an Angular application to load local files using the browseLocalFiles() method. This powerful feature allows you to easily integrate file loading functionality into your Angular applications, enabling users to work with local files directly in the browser.

By leveraging the TurboGUI library, we can take advantage of a well-maintained set of browser-related utilities without having to implement them ourselves. This can save development time and provide a more robust solution for browser interactions in your Angular applications.

Remember to handle errors and edge cases in a production environment, and consider adding file type and size restrictions to ensure a smooth user experience.

Happy coding!

TurboFramework