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我希望在组件发生更改时触发必需字段验证。该组件上有多个必填字段，需要填写以便用户进入下一页。我的想法是激发我的函数，该函数检查必填字段是否有空或空。如何在角度4中使用更改检测
我的问题是，我无法找到任何关于如何实现这个的例子。以下是我迄今得到的。
import { Component, Injectable, OnInit, Input, ChangeDetectorRef } from '@angular/core'
import { HttpModule } from '@angular/http';
import { CarReqFormService } from './carReqForm.service';
import { DropDownListItem } from './carReq-dropdownItem';
import { IMyOptions, IMyDateModel } from 'ngx-mydatepicker';
import { surgeryReservationModel } from './carReservationModel';
import { Router, ActivatedRoute, Params } from '@angular/router';
import { Location } from '@angular/common';
import 'rxjs/add/operator/switchMap';
import { AutoCompleteBoxRequest } from './autoCompleteBoxRequest';
@Component({
moduleId: module.id,
selector: 'uh-carReservationFormPage3',
templateUrl: './carReservationFormPage3.html',
providers: [carReqFormService]
})
export class carReservationFormPage3Component implements OnInit {
SurgicalPositionItems: DropDownListItem[];
private loading: boolean = true;
carReservationModel = new carReservationModel();
public isBusy: boolean;
constructor(private _carRequestFormService: carReqFormService,
private route: ActivatedRoute ,
private _router: Router,
private ref: ChangeDetectorRef) {
}
ngOnInit(): void {
this.getActivecaricalPositions();
this.isBusy = true;
var test;
this.route.params
.switchMap((params: Params) => this._carRequestFormService.getcarRequestById(+params['id']))
.subscribe(
data => {
this.carReservationModel = data;
this.isBusy = false;
},
error => {
console.log("Error", error);
this.isBusy = false;
},
() => {
console.log("Inside NgOnInit on Page 3" + this.carReservationModel.carRequestId);
this.isBusy = false;
});
}
}
是否有一个函数会触发任何更改，我可以调用我的函数来触发验证规则？
只要Angular为组件执行变更检测，就会触发ngDoCheck，@Input变更时会触发onChanges，但没有其他 –