Angular 有棱角的。如何有条件地显示标题?
我有一个按公寓编号排序的公寓对象的可观察数组(从firebase查询返回):Angular 有棱角的。如何有条件地显示标题?,angular,Angular,我有一个按公寓编号排序的公寓对象的可观察数组(从firebase查询返回): [ {number: 10, color: white, ...}, {number: 11, color: blue, ....}, {number: 20, color: red, ...} {number: 32, color: red, ...} ] 每个公寓都有一个号码 公寓号码的第一位数字决定了他的flor 例如: Apartment number: 32 = 3th floor Apar
[
{number: 10, color: white, ...},
{number: 11, color: blue, ....},
{number: 20, color: red, ...}
{number: 32, color: red, ...}
]
每个公寓都有一个号码
公寓号码的第一位数字决定了他的flor
例如:
Apartment number: 32 = 3th floor
Apartment number: 53 = 5th floor
每次楼层更改时,我都需要显示带有楼层编号的标题。有些人喜欢这样:
1th Floor:
- 10
- 11
- 12
...
2th Floor:
- 20
- 21
...
3th Floor:
- 30
- 31
....
如何使用ngFor和异步管道实现这一点
要简单地显示所有公寓的列表,我使用下面的代码:
<div *ngFor="let apartment of apartment$ | async">
<h2>{{apartment.number}}</h2>
</div>
{{公寓号码}
如果您只想使用一些模板逻辑(并使用async
)执行此操作,您可以利用*ngFor的index属性:
<div *ngFor="let apartment of apartments | async; let i = index">
<h1 *ngIf="i === 0 || (apartment.number / 10 >> 0) !== (apartments[i-1].number / 10 >> 0)">{{(apartment.number / 10 >> 0)}}th Floor {{apartment.number}}</h1>
<h2>{{apartment.number}}</h2>
</div>
{{(公寓号/10>>0)}四楼{{{公寓号}
{{公寓号码}
其中(plant.number/10>>0)
应给出数字
除以10,不带余数…以下是工作示例
ts代码:
import { Component } from '@angular/core';
@Component({
selector: 'my-app',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
floor: any[] = [];
apartments: Array<any> = [
{ number: 10, color: "white" },
{ number: 11, color: "blue" },
{ number: 20, color: "red" },
{ number: 32, color: "red" },
{ number: 33, color: "red" },
{ number: 34, color: "red" }
];
constructor() {
for (let i = 0; i < this.apartments.length; i++) {
this.calculateFloor(this.apartments[i]);
}
}
calculateFloor(apartment){
if (Math.floor(apartment.number / 10) > 0) {
if (this.floor.indexOf(Math.floor(apartment.number / 10)) == -1) {
this.floor.push(Math.floor(apartment.number / 10));
}
return { num: apartment.number, status: true, floor: Math.floor(apartment.number / 10) };
}
}
calculateApartment(apartment, floor){
if (Math.floor(apartment.number / 10) == floor) {
return true
} else {
return false
}
}
}
从'@angular/core'导入{Component};
@组成部分({
选择器:“我的应用程序”,
templateUrl:“./app.component.html”,
样式URL:['./app.component.css']
})
导出类AppComponent{
楼层:任何[]=[];
公寓:阵列=[
{编号:10,颜色:“白色”},
{编号:11,颜色:“蓝色”},
{编号:20,颜色:“红色”},
{编号:32,颜色:“红色”},
{编号:33,颜色:“红色”},
{编号:34,颜色:“红色”}
];
构造函数(){
for(设i=0;i0){
if(this.floor.indexOf(Math.floor(partment.number/10))=-1){
这个。楼层。推(数学。楼层(公寓号/10));
}
返回{num:partment.number,状态:true,楼层:Math.floor(partment.number/10)};
}
}
计算部门(公寓、楼层){
if(数学楼层(公寓编号/10)=楼层){
返回真值
}否则{
返回错误
}
}
}
HTML:
{{f}}第三层
{{calculateApartment(公寓,f)?公寓。编号:''}}
如果您想计算您可以建造的楼层
//Add to each this.apartments element a property:floor
this.apartments=this.apartments.map(ap=>
{
return {...ap,floor:Math.floor(ap.number/10)}
})
//Create an array with unique values of "floor"
//And add the property "apartments"
const floor=this.apartments.filter((item, pos)=> {
return this.apartments.findIndex(i=>item.floor==i.floor) == pos;
}).map(f=>{
return{
floor:f.floor,
apartments:this.apartments.filter(a=>a.floor==f.floor)
}
}
这是我第一次尝试,一个简单而优雅的解决问题的方法,但是。。。当我们使用异步管道时,
单元[i-1]
会导致错误<代码>类型错误:未定义不是对象(正在评估“\u co.plants[\u v.context.index].number”)谢谢。这就是我想要的解决方案,简单有效。只是做了一些小的调整,并将其组合成一个单独的可观察对象。
//Add to each this.apartments element a property:floor
this.apartments=this.apartments.map(ap=>
{
return {...ap,floor:Math.floor(ap.number/10)}
})
//Create an array with unique values of "floor"
//And add the property "apartments"
const floor=this.apartments.filter((item, pos)=> {
return this.apartments.findIndex(i=>item.floor==i.floor) == pos;
}).map(f=>{
return{
floor:f.floor,
apartments:this.apartments.filter(a=>a.floor==f.floor)
}
}