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Rodrigo Kamada
Rodrigo Kamada

Posted on • Updated on

Adding the log component to an Angular application

Introduction

Angular is a development platform for building WEB, mobile and desktop applications using HTML, CSS and TypeScript (JavaScript). Currently, Angular is at version 12 and Google is the main maintainer of the project.

ngx-logger is a simple log component library and allows messages to be displayed on the console and sent to the server using an HTTP request.

Prerequisites

Before you start, you need to install and configure the tools:

Getting started

Create the Angular application

1. Let's create the application with the Angular base structure using the @angular/cli with the route file and the SCSS style format.

ng new angular-logger
? Would you like to add Angular routing? Yes
? Which stylesheet format would you like to use? SCSS   [ https://sass-lang.com/documentation/syntax#scss                ]
CREATE angular-logger/README.md (1059 bytes)
CREATE angular-logger/.editorconfig (274 bytes)
CREATE angular-logger/.gitignore (604 bytes)
CREATE angular-logger/angular.json (3255 bytes)
CREATE angular-logger/package.json (1076 bytes)
CREATE angular-logger/tsconfig.json (783 bytes)
CREATE angular-logger/.browserslistrc (703 bytes)
CREATE angular-logger/karma.conf.js (1431 bytes)
CREATE angular-logger/tsconfig.app.json (287 bytes)
CREATE angular-logger/tsconfig.spec.json (333 bytes)
CREATE angular-logger/src/favicon.ico (948 bytes)
CREATE angular-logger/src/index.html (299 bytes)
CREATE angular-logger/src/main.ts (372 bytes)
CREATE angular-logger/src/polyfills.ts (2820 bytes)
CREATE angular-logger/src/styles.scss (80 bytes)
CREATE angular-logger/src/test.ts (788 bytes)
CREATE angular-logger/src/assets/.gitkeep (0 bytes)
CREATE angular-logger/src/environments/environment.prod.ts (51 bytes)
CREATE angular-logger/src/environments/environment.ts (658 bytes)
CREATE angular-logger/src/app/app-routing.module.ts (245 bytes)
CREATE angular-logger/src/app/app.module.ts (393 bytes)
CREATE angular-logger/src/app/app.component.scss (0 bytes)
CREATE angular-logger/src/app/app.component.html (24617 bytes)
CREATE angular-logger/src/app/app.component.spec.ts (1097 bytes)
CREATE angular-logger/src/app/app.component.ts (219 bytes)
✔ Packages installed successfully.
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2. Install and configure the Bootstrap CSS framework. Do steps 2 and 3 of the post Adding the Bootstrap CSS framework to an Angular application.

3. Configure the log settings in the src/environments/environment.ts and src/environments/environment.prod.ts files as below.

logger: {
  level: 'TRACE',
},
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4. Install the ngx-logger library.

npm install ngx-logger
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5. Import the HttpClientModule and LoggerModule modules. Configure the log settings. Change the app.module.ts file and add the lines as below.

import { HttpClientModule } from '@angular/common/http';
import { LoggerModule, NgxLoggerLevel } from 'ngx-logger';

import { environment } from '../environments/environment';

const environmentConfig: any = environment.logger;

imports: [
  BrowserModule,
  HttpClientModule,
  LoggerModule.forRoot({
    level: NgxLoggerLevel[environmentConfig.level],
    serverLogLevel: NgxLoggerLevel[environmentConfig.serverLevel],
    serverLoggingUrl: environmentConfig.serverUrl,
  } as any),
  AppRoutingModule,
],
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6. Remove the contents of the AppComponent class from the src/app/app.component.ts file. Import the NGXLogger service and create the log levels methods as below.

import { Component } from '@angular/core';
import { NGXLogger } from 'ngx-logger';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.scss'],
})
export class AppComponent {

  constructor(private logger: NGXLogger) {
  }

  public showTrace(): void {
    this.logger.trace('TRACE level');
  }

  public showDebug(): void {
    this.logger.debug('DEBUG level');
  }

  public showInfo(): void {
    this.logger.info('INFO level');
  }

  public showWarn(): void {
    this.logger.warn('WARN level');
  }

  public showError(): void {
    this.logger.error('ERROR level');
  }

  public showFatal(): void {
    this.logger.fatal('FATAL level');
  }

}
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7. Remove the contents of the src/app/app.component.html file. Add the log levels buttons as below.

<div class="container-fluid py-3">
  <h1>Angular Logger</h1>
  <div class="d-grid gap-2 col-4 mt-4 mx-auto">
    <button type="button" class="btn btn-sm btn-primary" (click)="showTrace()">Trace</button>
    <button type="button" class="btn btn-sm btn-success" (click)="showDebug()">Debug</button>
    <button type="button" class="btn btn-sm btn-info" (click)="showInfo()">Info</button>
    <button type="button" class="btn btn-sm btn-warning" (click)="showWarn()">Warn</button>
    <button type="button" class="btn btn-sm btn-danger" (click)="showError()">Error</button>
    <button type="button" class="btn btn-sm btn-secondary" (click)="showFatal()">Fatal</button>
  </div>
  <p class="mt-4 text-center">
    <span class="fw-bold me-1">Note:</span>
    <span class="fst-italic">See the messages displayed in the browser console.</span>
  </p>
</div>
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8. Run the application with the command below.

npm start

> angular-logger@1.0.0 start
> ng serve

✔ Browser application bundle generation complete.

Initial Chunk Files | Names         |      Size
vendor.js           | vendor        |   2.55 MB
styles.css          | styles        | 266.58 kB
polyfills.js        | polyfills     | 128.51 kB
scripts.js          | scripts       |  76.67 kB
main.js             | main          |  14.41 kB
runtime.js          | runtime       |   6.63 kB

                    | Initial Total |   3.03 MB

Build at: 2021-09-04T19:25:20.982Z - Hash: dcc562d0e20cf029eab3 - Time: 12067ms

** Angular Live Development Server is listening on localhost:4200, open your browser on http://localhost:4200/ **


✔ Compiled successfully.
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9. Ready! Access the URL http://localhost:4200/ and check if the application is working. See the application working on GitHub Pages and Stackblitz.

Angular Logger

The application repository is available at https://github.com/rodrigokamada/angular-logger.

This tutorial was posted on my blog in portuguese.

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