zoukankan      html  css  js  c++  java
  • [Angular] Configure an Angular App at Runtime

    It always again happens (especially in real world scenarios) that you need to configure your Angular app at runtime. That configuration might be fetched from some backend API, or it might be some simple JSON configuration sitting on your deployment server. The key here is that you want to be able to dynamically modify and adjust that configuration without the need to re-compile and re-deploy your application. Also, you most probably want that configuration to be loaded and ready once your application bootstrapping is done. In this lesson we learn how to make use of the APP_INITIALIZERto hook into Angular's initialization process. That will allow us to inject some configuration into our app just when it is about to start up.

    // app.module.ts
    
    const appInitializerFn = (configService: AppInitConfigService) => {
      return () => {
        return configService.loadAppConfig();
      };
    };
     ...
      providers: [
        AppInitConfigService,
        {
          provide: APP_INITIALIZER,
          useFactory: appInitializerFn,
          deps: [AppInitConfigService],
          multi: true
        }
      ],
    // app.init-config.service.ts
    
    import {Injectable} from '@angular/core';
    import {HttpClient} from '@angular/common/http';
    
    @Injectable()
    export class AppInitConfigService {
    
      private appConfig;
    
      constructor(private http: HttpClient) {
    
      }
    
      getConfig() {
        return this.appConfig;
      }
    
      loadAppConfig() {
        return this.http.get('/assets/data/app.config.json')
          .toPromise()
          .then((config) => this.appConfig = config);
      }
    }

    App will defer to load after the config is loaded.

    We can display the config's content in the component:

    import {ChangeDetectionStrategy, Component, OnInit} from '@angular/core';
    import {Observable} from 'rxjs/Observable';
    import {Store} from '@ngrx/store';
    
    import 'rxjs/add/operator/do';
    import 'rxjs/add/operator/shareReplay';
    import 'rxjs/add/operator/map';
    
    import * as fromRoot from '../../store/reducers/index';
    import * as authActions from '../../../auth/actions/auth';
    import {AuthService} from '../../../auth/services/auth.service';
    import {AppInitConfigService} from '../../../app.init-config.service';
    
    @Component({
      selector: 'ld-app',
      changeDetection: ChangeDetectionStrategy.OnPush,
      templateUrl: './ld-app.component.html',
      styleUrls: ['./ld-app.component.scss']
    })
    export class LdAppComponent implements OnInit {
    
      config: any;
      constructor(
           private configService: AppInitConfigService) {
        this.config = this.configService.getConfig();
      }
    
      ngOnInit() {
      }
    }
  • 相关阅读:
    FreeBSD 里面用 ADSL 来上网的设置
    功能齐全的DataGrid
    jsp中动态生成图像
    配置Struts应用解读Struts应用的两大配置文件
    spring 事务配置
    文件上传原理简单实现
    html中position两属性relative和absolute区别
    html 窗口参数详解
    hibernate联合主键的使用
    自动投票的一个脚本
  • 原文地址:https://www.cnblogs.com/Answer1215/p/8333045.html
Copyright © 2011-2022 走看看