既然昨天已經說了 http post 這件事，那今天就來說說 http get 這部份吧！

今天的資料依然使用 FakeStoreAPI
樣式套用 Angular Material

情境

從 api 取得列表後，把資料渲染到 html 上

import Module

app.module.ts import HttpClientModule，

import { NgModule } from "@angular/core";
import { BrowserModule } from "@angular/platform-browser";
import { FormsModule } from "@angular/forms";

import { AppComponent } from "./app.component";
import { MaterialModule } from "./material-module";
import { HttpClientModule } from "@angular/common/http";

@NgModule({
  imports: [
    BrowserModule,
    HttpClientModule, // 使用於 http 請求
    FormsModule,
    MaterialModule, // Angular Material
  ],
  declarations: [AppComponent],
  bootstrap: [AppComponent],
})
export class AppModule {}

建立服務

建立一個 service 放置 api
service.ts

import { HttpClient } from '@angular/common/http';
import { Injectable } from '@angular/core';
import { catchError, Observable } from 'rxjs';

@Injectable()
export class AppService {
  constructor(private httpClient: HttpClient) {}

  fetchProd(): Observable<any> {
    const url = `https://fakestoreapi.com/products`;
    return this.httpClient.get<any>(url).pipe(
      catchError((err, caught) => {
        console.error(err);
        throw err;
      })
    );
  }
}

記得 catchError 這裡可以處理 API 錯誤時，決定怎麼樣的動作

取得 API 資料 渲染到頁面上

.ts

import { Component, OnInit } from '@angular/core';
import { Observable, tap } from 'rxjs';
import { AppService } from './app.service';

@Component({
  selector: 'my-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
  providers: [AppService] // 將 AppService 的服務注入
})
export class AppComponent implements OnInit {
  products$ = new Observable<any>();

  constructor(private appService: AppService) {}

  ngOnInit(): void {
    this.products$ = this.appService.fetchProd();
  }
}

.html

<ng-container *ngIf="products$ | async as products">
  <ng-container *ngFor="let item of products">
    <div class="products">
    <mat-card>
      <mat-card-header>
        <mat-card-title>{{ item.title }}</mat-card-title>
        <mat-card-subtitle>{{ item.category }}</mat-card-subtitle>
      </mat-card-header>
      <img mat-card-image src="{{ item.image }}" />
      <mat-card-content>
        <p>{{ item.description }}</p>
      </mat-card-content>
    </mat-card>
    </div>
  </ng-container>
</ng-container>

這裡使用 Async Pipe 將資料渲染出來，直接從 template 訂閱資料

範例：https://stackblitz.com/edit/angular-ivy-6bbh3n