从Angular 4中的选择选项中获取价值

Question

如何从 Angular 4 中的选择选项中获取值？

我想将它分配给 component.ts 文件中的一个新变量。我试过了，但什么也没输出。

你也可以使用 [(ngModel)] 吗？

component.html

<form class="form-inline" (ngSubmit)="HelloCorp(f)" #f="ngForm">
     <div class="select">
         <select class="form-control col-lg-8" #corporation required>
             <option *ngFor="let corporation of corporations" [value]="corporationObj">{{corporation.corp_name}}</option>    
         </select>
             <button type="submit" class="btn btn-primary manage">Submit</button>
     </div>
</form>

组件.ts

HelloCorp() {
const corporationObj = corporation.value;
}

Answer 1

一般情况下（请参阅此处的 Stackblitz：https://stackblitz.com/edit/angular-gh2rjx）：

HTML

<select [(ngModel)]="selectedOption">
   <option *ngFor="let o of options">
      {{o.name}}
   </option>
</select>
<button (click)="print()">Click me</button>

<p>Selected option: {{ selectedOption }}</p>
<p>Button output: {{ printedOption }}</p>

打字稿

export class AppComponent {
  selectedOption: string;
  printedOption: string;

  options = [
    { name: "option1", value: 1 },
    { name: "option2", value: 2 }
  ]
  print() {
    this.printedOption = this.selectedOption;
  }
}

---

在您的具体情况下，您可以像这样使用 ngModel：

<form class="form-inline" (ngSubmit)="HelloCorp()">
     <div class="select">
         <select [(ngModel)]="corporationObj" class="form-control col-lg-8" #corporation required>
             <option *ngFor="let corporation of corporations"></option>    
         </select>
         <button type="submit" class="btn btn-primary manage">Submit</button>
     </div>
</form>

HelloCorp() {
  console.log("My input: ", corporationObj);
}

Answer 2

export class MyComponent implements OnInit {

  items: any[] = [
    { id: 1, name: 'one' },
    { id: 2, name: 'two' },
    { id: 3, name: 'three' },
    { id: 4, name: 'four' },
    { id: 5, name: 'five' },
    { id: 6, name: 'six' }
  ];
  selected: number = 1;

  constructor() {
  }
  
  ngOnInit() {
  }
  
  selectOption(id: number) {
    //getted from event
    console.log(id);
    //getted from binding
    console.log(this.selected)
  }

}

<div>
  <select (change)="selectOption($event.target.value)"
  [(ngModel)]="selected">
  <option [value]="item.id" *ngFor="let item of items">{{item.name}}</option>
   </select>
</div> 

Answer 3

HTML 代码

    <form class="form-inline" (ngSubmit)="HelloCorp(modelName)">
        <div class="select">
            <select class="form-control col-lg-8" [(ngModel)]="modelName" required>
                <option *ngFor="let corporation of corporations" [ngValue]="corporation">
                    {{corporation.corp_name}}
                </option>    
            </select>
            <button type="submit" class="btn btn-primary manage">Submit</button>
        </div> 
    </form>

组件代码

HelloCorp(corporation) {
    var corporationObj = corporation.value;
}

Answer 4

您只需将[(ngModel)] 放在您的选择元素上：

<select class="form-control col-lg-8" #corporation required [(ngModel)]="selectedValue">

Answer 5

这其实很简单。

请注意我是

我。将 name="selectedCorp" 添加到您的 select 开始标签，然后

二。将您的 [value]="corporationObj" 更改为 [value]="corporation"，这与您的 *ngFor= 中的 corporation 一致“让corporation 公司”声明：

 <form class="form-inline" (ngSubmit)="HelloCorp(f)" #f="ngForm">
   <div class="select">
     <select class="form-control col-lg-8" #corporation name="selectedCorp" required>
       <option *ngFor="let corporation of corporations" [value]="corporation">{{corporation.corp_name}}</option>
     </select>
     <button type="submit" class="btn btn-primary manage">Submit</button>
   </div>
 </form>

然后在您的 .ts 文件中，您只需执行以下操作：

HelloCorp(form: NgForm) {
   const corporationObj = form.value.selectedCorp;
}

而 const corporationObj 现在是选定的公司对象，它将包含您定义的公司类的所有属性。

注意：

在 html 代码中，通过语句 [value]="corporation"，corporation（来自 *ngFor="let corporation ofcorporats") 绑定到 [value]，name 属性将获得 value。

由于 name 是 "selectedCorp"，因此您可以通过在 . ts 文件。

顺便说一句，实际上您的 "select" 开始标记中不需要 "#corporation"。

Answer 6

    //in html file
    <div class="row">
                <div class="col-md-6">
                    <div class="form-group">
                        <label for="name">Country</label>
                        <select class="form-control" formControlName="country" (change)="onCountryChange($event.target.value)">
                            <option disabled selected value [ngValue]="null"> -- Select Country  -- </option>
                            <option *ngFor="let country of countries" [value]="country.id">{{country.name}}</option>
                            <div *ngIf="isEdit">
                                <option></option>
                            </div>
                        </select>
                      </div>   
                </div>
            </div>
            <div class="help-block" *ngIf="studentForm.get('country').invalid && studentForm.get('country').touched">
                <div *ngIf="studentForm.get('country').errors.required">*country is required</div>
            </div>
            <div class="row">
                <div class="col-md-6">
                    <div class="form-group">
                        <label for="name">State</label>
                        <select class="form-control" formControlName="state" (change)="onStateChange($event.target.value)">
                            <option disabled selected value [ngValue]="null"> -- Select State -- </option>
                            <option *ngFor="let state of states" [value]="state.id">{{state.state_name}}</option>
                        </select>
                      </div>   
                </div>
            </div>
            <div class="help-block" *ngIf="studentForm.get('state').invalid && studentForm.get('state').touched">
                <div *ngIf="studentForm.get('state').errors.required">*state is enter code hererequired</div>
            </div>
            <div class="row">
                <div class="col-md-6">
                    <div class="form-group">
                        <label for="name">City</label>
                        <select class="form-control" formControlName="city">
                            <option disabled selected value [ngValue]="null"> -- Select City -- </option>
                            <option *ngFor="let city of cities" [value]="city.id" >{{city.city_name}}</option>
                        </select>
                      </div>   
                </div>
            </div>
            <div class="help-block" *ngIf="studentForm.get('city').invalid && studentForm.get('city').touched">
                <div *ngIf="studentForm.get('city').errors.required">*city is required</div>
            </div>
    //then in component
    onCountryChange(countryId:number){
   this.studentServive.getSelectedState(countryId).subscribe(resData=>{
    this.states = resData;
   });
  }
  onStateChange(stateId:number){
    this.studentServive.getSelectedCity(stateId).subscribe(resData=>{
     this.cities = resData;
    });
   }`enter code here`