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html - 如何在Angular 8中获取多个复选框的值

问题描述

我正在尝试获取所选复选框的值。我有以下代码：

<div style="background-color:lightblue;" >
    <div class="content">
       <label class="label">Province</label>
       <div class="form-check form-check-inline" *ngFor = "let province of utilities.Provinces; let i of index">    
           <label class="form-check-label" for="inlineCheckbox1" >{{province}}</label>
           <input class="form-check-input" [formControl]= "province" (change)="getSelectedProvinces()" type="checkbox" id="inlineCheckbox{{i}}" value="option1"> 
      </div>
 </div>

在 .ts 我有以下

import { Component, OnInit } from '@angular/core';
import { UtilitiesService } from '../_services/utilities.service';
import { Utilities } from '../models/utilities';
import { forEach } from '@angular/router/src/utils/collection';

@Component({
selector: 'app-filtering',
templateUrl: './filtering.component.html',
styleUrls: ['./filtering.component.css']
})
export class FilteringComponent implements OnInit {
   utilities: Utilities;
   provinces:  string[] = [];
   selectedProvinces: string[] = [];
   selectedCategories: string[] = [];

   constructor(private utilityService: UtilitiesService) { }

   ngOnInit() {
     this.loadUtilities();
  }

  loadUtilities() {
    this.utilityService.getJSON().subscribe((utilities: Utilities) => {
    this.utilities = utilities;
    });

    for (const  province of this.utilities.Provinces) {
      this.provinces.push(province);
    }
  }

  getSelectedProvinces() {
      this.selectedProvinces = [];
      this.utilities.Provinces.forEach((_province, i) => {
          if (_province.value) {
          this.selectedProvinces.push(this.provinces[i]);
      }
  });
 console.log(this.selectedProvinces);
}

}

在我的utilities.ts我有以下内容：

export interface Utilities {
  Provinces: Array<string>;
}

我的服务是这样写的：

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { Utilities } from '../models/utilities';
import { Observable } from 'rxjs';

@Injectable({
  providedIn: 'root'
})
export class UtilitiesService {

constructor(private http: HttpClient) {}

public getJSON(): Observable<Utilities> {
   return this.http.get<Utilities>('./assets/utilities.json');
}

}

即具有以下内容的 Json：

{
   "Provinces":["East","North West","North"]
}

当我尝试这样做时，出现以下错误：

TypeError: Cannot read property 'Provinces' of undefined.

问题是，当我删除[formControl]= "province" (change)="getSelectedProvinces()"时，至少我可以在我的页面上显示省份。

我该怎么办？

标签： htmlangulartypescriptcheckbox

解决方案

我终于使用下面的代码解决了我的问题：

<div class="content">
<label class="label">Province</label>
<div class="form-check form-check-inline" *ngFor="let province of utilities.Provinces">    
    <label class="form-check-label" for="{{province}}">{{province}}</label>
    <input class="form-check-input" (change)="onChangeCategory(province, $event.target.checked)"name="{{ province}}" type="checkbox" id="{{province}}"> 
</div>

在我的.ts中，我有以下内容：

onChangeProvince(province: string, isChecked: boolean) {
   if (isChecked) {
         this.selectedProvinces.push(province);
   } else {
       const index = this.selectedProvinces.indexOf(province);
       this.selectedProvinces.splice(index, 1);
   }

 console.log(this.selectedProvinces);

}

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