Angular2：在选择组件中获取选定选项

Question

I am using angular 2.0.0-rc.4.

I have a form (parent component), and I have in it some drop-down lists from other components, each dropdown has ts and html template else where, each one get its data from its component. When submitting the form I need the selected value of each one. How can I access it from the parent ?

-Parent Form HTML:

<form class="" (submit)="submitNewModel($event, label.value)">
    <div class="form-group">
      <label for="label" class="control-label"> Label </label>
      <input type="text" name="label" #label class="form-control" placeholder="Model's label">
    </div>
    <styles-dropdown></styles-dropdown>
    <colors-dropdown></colors-dropdown>
    <modes-dropdown></modes-dropdown>
    <shapes-dropdown></shapes-dropdown>
    <button type="submit" name="button">Create new model</button>
</form>

-Parent ts :

import { Component } from '@angular/core';

...

@Component({
  selector: 'models',
  templateUrl: 'app/models/models.component.html',
  directives: [
    StylesDropDownComponent,
    ...
  ]
})
export class ModelsComponent {

  constructor(){
  }

  submitNewModel(event, label) {
    event.preventDefault();
    console.log('Value label', label);
    console.log(event);
    //How do I get selected values here ?
  }
}

-Drop down component HTML:

<div class="portlet-body">
  <div class="form-group">
    <label for="styles" class="control-label"> Style </label>
    <select name="style-select" id="styles" class="form-control select2">
      <option value="">Select style</option>
      <option *ngFor="let style of styles" value="{{style.id}}">{{ style.label }}</option>
    </select>
  </div>

-Drop down ts :

import { Component } from '@angular/core';

import { ClientHttp } from '../../common/cigma-http';
import { StylesComponent } from '../styles.component';

@Component({
  selector: 'styles-dropdown',
  templateUrl: 'app/styles/styles-dropdown/styles.dropdown.component.html',
})
export class StylesDropDownComponent extends StylesComponent  {
  constructor(protected cigmaHttp: CigmaHttp) {
    super(cigmaHttp)
  }
}

All other dropdown component have the same structure as the one above.

Answer 1

使用evenEmitter将值从父组件传递给子组件

Answer 2

So after playing around and reading some useful topics:

To passe data from parent to nested component, we need to use @Input decorator:

@Component({
  selector: 'child',
  template: 'child.component.html'
})
export class ChildComponent {  
  @Input() title:string;
}

Now we can pass data to that property from the parent.

@Component({
  selector: 'parent',
  template: 'parent.component.html',
  directives: [ChildComponent]
})
export class ParentComponent {  
  childTitle:string = 'Information passed to child';
}

And of course:

/* parent.component.html */
<div>  
  <h1>Parent component</h1>
  <child[title]='childTitle'></child>
</div> 

Without the @input decorator the child component wont know about the passed data from the parent.

---

And to pass data from Child to Parent we need to use eventEmitter. You can read more here .