@d78ng/file-loader

Provides Angular service to simplify file loading (for example configuration) from a local path on the server.

Getting started

Prerequisities

An existing Angular application. Angular CLI can be used to create one.

Installing

npm i -s @d78ng/file-loader

How to use

Loading a single file during application initialization:

app.module.ts:

// Define imports:
import {FileLoaderService} from '@d78ng/file-loader';

// Factory function for APP_INITIALIZER: 
export function init(cfg: FileLoaderService) {
  return () => new Promise(async(resolve) => {
    try {
      await cfg.load('/cfg/config.json', '/assets/config.json');
      resolve(true);
    } catch {
      resolve(false);
    }
  });
}

//...

@NgModule({
  //...
  // Define the required providers:
  providers: [
    HttpClient,
    LocalFileService,
    {provide: APP_INITIALIZER, useFactory: init, deps:[LocalFileService], multi: true}
  ],
  //...
})

(Alternatively) Loading multiple files:

app.tokens.ts:

import {InjectionToken} from '@angular/core';
import {FileLoaderService} from '../../projects/file-loader/src/lib/file-loader.service';

// Define an  injection token for each of the files:
// (First file contains configuration, second file contains version info) 
export const LOCAL_FILE_CFG: InjectionToken<FileLoaderService> = new InjectionToken<FileLoaderService>("local-file.cfg");
export const LOCAL_FILE_VER: InjectionToken<FileLoaderService> = new InjectionToken<FileLoaderService>("local-file.ver");

app.module.ts:

// Define imports
import {FileLoaderService} from '@d78ng/file-loader';

// Factory function for FileLoaderService creation:
export function initFLS(http: HttpClient) {
  return new FileLoaderService(http);
}

// Factory function for APP_INITIALIZER: 
export function init(cfg: FileLoaderService, ver: FileLoaderService) {
  return () => new Promise(async(resolve) => {
    try {
      await Promise.all([
        cfg.load('/cfg/config.json', '/assets/config.json'),
        ver.load('/assets/version.json')
      ]);
      resolve(true);
    } catch {
      resolve(false);
    }
  });
}

//...

@NgModule({
  //...
  // Define the required providers:
  providers: [
    HttpClient,
    {provide: LOCAL_FILE_CFG, useFactory: initFLS, deps: [HttpClient]},
    {provide: LOCAL_FILE_VER, useFactory: initFLS, deps: [HttpClient]},
    {provide: APP_INITIALIZER, useFactory: init, deps:[LOCAL_FILE_CFG, LOCAL_FILE_VER], multi: true}
  ],
  //...
})

Access the data:

app.component.ts:

export class AppComponent {
  
  private backendUrl: string;

  constructor(configService: FileLoaderService) {
    this.backendUrl = configService.data.backendUrl;
  }
}

Versioning

This project uses SemVer for versioning. For the versions available, see the tags on its repository.

License

This project is licensed under the MIT License - see the LICENSE.md file for details.

See also

Project home page
Reference documentation
NPM package