[英]Dropdown populated from json data
我希望我的下拉菜單顯示我的數據中的2017年和2018年。 2017和2018在我的json數據文件中重復很多次。 但是我希望在選擇時顯示所有2017年數據,並在選擇時顯示所有2018年數據。 當前,它顯示所有數據,並且下拉列表中的填充過多。
這是下拉菜單的HTML代碼:
<div class="row justify-content-center">
<div class="col-4s">
<p>Financial Year:</p>
</div>
<div class="col-4s">
<select>
<option *ngFor="let volumes of volumes">{{ volumes.month |
date: 'yyyy' }}</option>
</select>
</div>
</div>
Angular4代碼:導出類VehicleVolumeEditComponent實現OnInit {
volumes: Volumes[];
groupedVolumes : any;
constructor(private volumeService: VolumeService, private router: Router) {
this.volumeService.getVolumes().subscribe(volumes => {
this.volumes = volumes;
this.groupedVolumes = this.group(this.volumes);
this.dataOk = true;
}
}
json文件:
[
{
"id": 1,
"month": "2017-03-01"
}
{
"id": 2,
"month": "2017-04-01"
}
{
"id": 3,
"month": "2017-05-01"
}
{
"id": 4,
"month": "2017-06-01"
}
{
"id": 5,
"month": "2017-07-01"
}
{
"id": 6,
"month": "2017-08-01"
}
{
"id": 7,
"month": "2017-09-01"
}
{
"id": 8,
"month": "2017-10-01"
}
{
"id": 9,
"month": "2017-11-01"
}
{
"id": 10,
"month": "2017-12-01"
}
{
"id": 11,
"month": "2018-01-01"
}
{
"id": 12,
"month": "2018-02-01"
}
{
"id": 13,
"month": "2018-03-01"
}
]
我會像這樣過濾掉數組中的唯一值-
this.unique_volumes = this.volumes.slice().map(value => value.month = new Date(value.month).getFullYear()).filter((years, index, array) => array.indexOf(years) === index);
然后在HTML,我會遍歷所有的unique_volumes
而不是volumes
。
<option *ngFor="let volumes of unique_volumes">{{ volumes }}</option>
嘗試這個
import {DatePipe} from '@angular/common';
.
.
volumes: Volumes[];
years: [] = [];
groupedVolumes : any;
constructor(private volumeService: VolumeService, private router: Router, private datePipe: DatePipe) {
}
ngOnInit(){
this.volumeService.getVolumes().subscribe(volumes => {
this.volumes = volumes;
for(let volume of volumes){
if(this.years.indexOf(datePipe.formatDate(volume.month, 'yyyy')) === -1)
this.years.push(datePipe.formatDate(volume.month, 'yyyy'));
}
this.groupedVolumes = this.group(this.volumes);
this.dataOk = true;
}
}
在html中使用它:
<div class="row justify-content-center">
<div class="col-4s">
<p>Financial Year:</p>
</div>
<div class="col-4s">
<select>
<option *ngFor="let year of years">{{ year }}</option>
</select>
</div>
</div>
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.