Javascript 通过HTML初始化Angular 2中组件的正确方法
我有一个组件,它从外部获取一些参数,然后根据这些参数构建其其余属性:Javascript 通过HTML初始化Angular 2中组件的正确方法,javascript,angular,ionic-framework,ionic2,Javascript,Angular,Ionic Framework,Ionic2,我有一个组件,它从外部获取一些参数,然后根据这些参数构建其其余属性: import { Component, Input } from '@angular/core'; import { NavController } from 'ionic-angular'; /* Info card for displaying information in the homepage or another places */ @Component({ selector: 'info-ca
import { Component, Input } from '@angular/core';
import { NavController } from 'ionic-angular';
/*
Info card for displaying information in the homepage or another places
*/
@Component({
selector: 'info-card',
templateUrl: 'infocard.html'
})
export class InfoCard {
icon;
@Input() card = {
title: '',
description: '',
image: null,
type: 0
}
constructor(public navCtrl: NavController) {
// TODO: Complete type list
switch(this.card.type){
case 0: // Pubs/Entertainment
this.icon = "beer"; break;
case 1: // Restaurants
this.icon = "restaurant"; break;
case 2: // Friends
this.icon = "person"; break;
case 3: // Groups of people (private chats)
this.icon = "people"; break;
case 4: // Objective
this.icon = "checkbox-outline"; break;
default:
this.icon = "alert"; break;
}
// Image path
if(this.card.image){
this.card.image = '../../assets/infocards/'+this.card.image;
}
}
}
在构造器中,您可以看到如何根据卡的类型设置其图标。此外,图像只有在与“null”不同时才会被渲染,但我只想从其名称之外传递,因此我将文件夹的实际路径放入构造函数中,并在末尾连接图像名称
我想没什么奇怪的。然后,我尝试在代码中使用此组件:
<info-card *ngFor="let card of testCards" [card]="card">
</info-card>
卡片显示“正确”。我的意思是,模板呈现正常,但图标和图像(取决于构造函数)都不能正常工作。类型0始终存在,因此我总是看到“啤酒”图标,并且图像被破坏(因为它不是指向正确的目录,而是指向一个名称)
这导致了以下问题:构造函数何时运行?我以为在构造函数初始化之前会添加一个@Input值,但我想我错了
我应该怎么做才能正确地构建从HTML传递数据的组件
我只想在属性“card”传递到组件后执行一些代码您需要使用:
您可能没有使用正确的属性、类和样式bindings@FabioAntunes你能进一步解释一下吗?你必须使用[attr.icon]=“icon”和[src]=“card.image”@FabioAntunes我想你还不明白这个问题。。。不是你的错,也许我解释得不好。信息显示得非常完美,真的!问题是,在我传递“card”参数之后,我需要一些代码来工作。该代码对未显示的数据进行了一些更改,因为我正在将其放入构造函数中,并且它在传递参数之前运行。ahhhh好的,您希望
ngOnChanges
import { Component, Input, OnChanges } from '@angular/core';
import { NavController } from 'ionic-angular';
/*
Info card for displaying information in the homepage or another places
*/
@Component({
selector: 'info-card',
templateUrl: 'infocard.html'
})
export class InfoCard implements OnChanges {
icon;
@Input() card = {
title: '',
description: '',
image: null,
type: 0
}
constructor(public navCtrl: NavController) {
}
ngOnChanges(changes) {
//changes will have your old card value and the new one
switch(this.card.type){
case 0: // Pubs/Entertainment
this.icon = "beer"; break;
case 1: // Restaurants
this.icon = "restaurant"; break;
case 2: // Friends
this.icon = "person"; break;
case 3: // Groups of people (private chats)
this.icon = "people"; break;
case 4: // Objective
this.icon = "checkbox-outline"; break;
default:
this.icon = "alert"; break;
}
// Image path
if(this.card.image){
this.card.image = '../../assets/infocards/'+this.card.image;
}
}
}