Angular - 在多个组件中包含 html 的最佳方法是什么？

Question

I need to put a loading in multiple components of my project. So instead of putting the same HTML over and over again across the components, I need to know what's the best way to not repeat code, but I don't know if this is correct thing to do. I have created a component called loading-graphic , which I bind it in every HTML file of the respective components. I read about ngTemplateOutlet and ngContent , but to be honest it doesn't make sense in my head to use it for this case (and I don't get it too... I'm a beginner on it). So, on what should I bet? Thanks.

Answer 1

Base on your question, I think creating Reusable Components with NgTemplateOutlet would be the best solution to avoid repeating HTML in different component Templates. It allows you to pass parameters base on your host component and makes your Angular app easier to test and develop since it sllows easily modified reusable component for various use cases without having to modify individual components itself.

Since you are a begginer I am going to Illustrate simple way of using NgTemplateOutlet, however dive deep later on Templates and Stamps.

Imaging you have a reusable Search component where you want to hide a check box base on the parent component. Your Template will look like below.

we pass data from the parent component to the child/Search component using @Input and property binding, so we define which checkboxes to hide base on Parent component.

here is the code sample for Search Component

 search.component.ts ====================== import { Component, OnInit, Output, EventEmitter, Input } from '@angular/core'; @Component({ selector: 'app-search', templateUrl: './app-search.component.html', styleUrls: ['./app-search.component.css'] }) export class AppSearchComponent implements OnInit { accountName: string = ''; @Output() accountSearchChange = new EventEmitter<string>(); //1. Event Binding to pass data from Child to Parent Component ->Int @Input() searchMode: 'account' | 'holder' | 'distribution' = 'account'; //Use NgTemplateOutlet for reusable componenet constructor() { } ngOnInit() { } //2. Event Binding to pass data from Child to Parent Component ->Invoke Emit doSearchFilter(searchText: string) { console.log('Search Child: doSearchFilter -> ' + searchText); this.accountSearchChange.emit(searchText); } clearFilters() { console.log('Account Search: Clear Filter is called'); this.accountName = ''; } }

 search.component.html ===================== <ng-container [ngSwitch]="searchMode"> <div class="input-full-width" *ngSwitchCase="'account'"> <mat-checkbox class="example-container check-full-width">Show active and pending only</mat-checkbox> </div> <div class="input-full-width" *ngSwitchCase="'holder'"> <mat-checkbox class="example-container check-full-width">View only holders with missing requirements</mat-checkbox> </div> <div class="input-full-width" *ngSwitchCase="'holder'"> <mat-checkbox class="example-container check-full-width">View only active Holders</mat-checkbox> </div> </ng-container>

I am using Search component inside Account component and below is the code sample. in HTML file i am referring app-search css selector and pass the search Mode defined in ts.

 import { Component, OnInit, ViewChild, AfterViewInit } from '@angular/core'; import { MatSort, MatTableDataSource, MatPaginator } from '@angular/material'; import { Router } from "@angular/router"; import { Observable } from 'rxjs'; import { AccountService } from 'src/app/core/services/account.service'; import { Deal } from 'src/app/core/models/deal'; @Component({ selector: 'app-account', templateUrl: './account.component.html', styleUrls: ['./account.component.css'] }) export class AccountsComponent implements OnInit, AfterViewInit { displayedColumns: string[] = ['accountId', 'accountShortName', 'accountType']; public dealDataSource = new MatTableDataSource<Deal>(); dealsObservable: Observable<Deal[]>; searchMode = 'distribution'; isLoadingResults = true; @ViewChild(MatSort) sort: MatSort; @ViewChild(MatPaginator) paginator: MatPaginator; constructor(private router: Router, private api: AccountService) { } ......................................................

 <app-search (accountSearchChange)='doFilter($event)' [searchMode]="searchMode"></app-search>

Hope this is clear.

Answer 2

i think loading component is not a bad Idee. Use loading component in your app-root component. You can use a loading.service and interceptor to display or hide the component. You will get automatically a Loading Indicator for each API call.

sample: https://medium.com/@zeljkoradic/loader-bar-on-every-http-request-in-angular-6-60d8572a21a9