问题
In Angular2 (Beta 6) I have a component for a main menu.
<mainmenu></mainmenu>
I want to bind a boolean for wide or narrow. So I made it into this:
<mainmenu [(menuvisible)]="true"></mainmenu>
But what I want (I think) is to bind to a javascript class property (as I may have other things to bind but want to be tidy by using a single class in the component).
I get an error
EXCEPTION: Template parse errors: Invalid property name 'menumodel.visible' ("
][(menumodel.visible)]="menumodel.visible">
If I try the same with a single variable instead of a class I get:
Template parse errors: Parser Error: Unexpected token '='
However this (one way binding?) does seem to work (but I might want to trigger the menu to go wide/narrow from another component so felt this should be a two-way data bound property):
<menu [vis]="true"></menu>
This is a bit of my menu component:
@Component({
selector: 'menu',
templateUrl: './app/menu.html',
providers: [HTTP_PROVIDERS, ApplicationService],
directives: [ROUTER_DIRECTIVES, FORM_DIRECTIVES, NgClass, NgForm]
})
export class MenuComponent implements OnInit {
mainmenu: MainMenuVM;
constructor(private _applicationService: ApplicationService) {
this.mainmenu = new MainMenuVM();
}
// ...ngOnInit, various functions
}
Here is my MainMenu View Model class
export class MainMenuVM {
public visible: boolean;
constructor(
) { this.visible = true; }
}
I'm trying to create a menu which has icons and text, but can go narrow to just show icons. I will emit this event upwards to a parent component to alter the position of the container next to the menu. Triggering a content container to maximised will trigger the menu to go narrow - I am not saying this is the best way, but I would like to resolve this particular question before going deeper.
Please note: I am not databinding to an input control here - just databinding to a component so I can then modify the UI.
This is from the Angular cheatsheet
<my-cmp [(title)]="name">
Sets up two-way data binding. Equivalent to: <my-cmp [title]="name" (titleChange)="name=$event">
Thanks in advance!
UPDATE
Integrating the code from the accepted answer and adapting for my particular use case here the final working code:
app.html
...header html content
// This is what I started with
<!--<menu [menuvisible]="true" (menuvisibleChange)="menuvisible=$event"></menu>-->
// This is two way data binding
// 1. Banana-in-a-box is the input parameter
// 2. Banana-in-a-box is also the output parameter name (Angular appends it's usage with Change in code - to follow shortly)
// 3. Banana-in-a-box is the short hand way to declare the commented out code
// 4. First parameter (BIAB) refers to the child component, the second refers the variable it will store the result into.
// 5. If you just need an input use the remmed out code with just the first attribute / value
<menu [(menuvisible)]="menuvisible"></menu>
.. div content start
<router-outlet></router-outlet>
.. div content end
app.component.ts (root)
export class AppComponent implements OnInit{
menuvisible: Boolean;
}
menu.component.ts (child of root)
export class MenuComponent implements OnInit {
// Parameters - notice the appending of "Change"
@Input() menuvisible: boolean;
@Output() menuvisibleChange: EventEmitter<boolean> = new EventEmitter<boolean>();
// Init
ngOnInit() {
// Populate menu - fetch application list
this.getApplications();
// Initially we want to show/hide the menu depending on the input parameter
(this.menuvisible === true) ? this.showMenu() : this.hideMenu();
}
//...more code
}
menu.html
<div id="menu" [ngClass]="menuStateClass" style="position: absolute; top:0px; left: 0px;z-index: 800; height: 100%; color: #fff; background-color: #282d32">
<div style="margin-top: 35px; padding: 5px 0px 5px 0px;">
<ul class="menuList" style="overflow-x: hidden;">
<li>IsMenuVisible:{{menuvisible}}</li>
<li style="border-bottom: 1px solid #3d4247"><a (click)="toggleMenu()"><i class="fa fa-bars menuIcon" style="color: white; font-size: 16px;"></i></a></li>
<li *ngFor="#app of applications">
<a [routerLink]="[app.routerLink]">
<i class="menuIcon" [ngClass]="app.icon" [style.color]="app.iconColour" style="color: white;"></i>
<span [hidden]="menuStateTextHidden">{{ app.name }}</span>
</a>
</li>
</ul>
</div>
</div>
Remember to import what you need e.g.
import {Component, EventEmitter, OnInit, Input, Output} from 'angular2/core';
Highly recommend this video on You Tube: Angular 2 Tutorial (2016) - Inputs and Outputs
回答1:
For two-way binding you need something like:
@Component({
selector: 'menu',
template: `
<button (click)="menuvisible = !menuvisible; menuvisibleChange.emit(menuvisible)">toggle</button>
<!-- or
<button (click)="toggleVisible()">toggle</button> -->
`,
// HTTP_PROVIDERS should now be imports: [HttpModule] in @NgModule()
providers: [/*HTTP_PROVIDERS*/, ApplicationService],
// This should now be added to declarations and imports in @NgModule()
// imports: [RouterModule, CommonModule, FormsModule]
directives: [/*ROUTER_DIRECTIVES, FORM_DIRECTIVES, NgClass, NgForm*/]
})
export class MenuComponent implements OnInit {
@Input() menuvisible:boolean;
@Output() menuvisibleChange:EventEmitter<boolean> = new EventEmitter<boolean>();
// toggleVisible() {
// this.menuvisible = !this.menuvisible;
// this.menuvisibleChange.emit(this.menuvisible);
// }
}
And use it like
@Component({
selector: 'some-component',
template: `
<menu [(menuvisible)]="menuVisibleInParent"></menu>
<div>visible: {{menuVisibleInParent}}</div>
`
directives: [MenuComponent]
})
class SomeComponent {
menuVisibleInParent: boolean;
}
回答2:
I've created a short plunkr.
ngModel Like Two-Way-Databinding for components
You have at least two possibilities to to create a two way databinding for components
V1: With ngModel Like Syntax, there you have to create a @Output property with the same name line the @Input property + "Change" at the end of the @Output property name
@Input() name : string;
@Output() nameChange = new EventEmitter<string>();
with V1 you can now bind to the Child Component with the ngModel Syntax
[(name)]="firstname"
V2. Just create one @Input and @Output property with the naming you prefer
@Input() age : string;
@Output() ageChanged = new EventEmitter<string>();
with V2 you have to create two attributes to get the two way databinding
[age]="alter" (ageChanged)="alter = $event"
Parent Component
import { Component } from '@angular/core';
@Component({
selector: 'my-app',
template: `<p>V1 Parentvalue Name: "{{firstname}}"<br/><input [(ngModel)]="firstname" > <br/><br/>
V2 Parentvalue Age: "{{alter}}" <br/><input [(ngModel)]="alter"> <br/><br/>
<my-child [(name)]="firstname" [age]="alter" (ageChanged)="alter = $event"></my-child></p>`
})
export class AppComponent {
firstname = 'Angular';
alter = "18";
}
Child Component
import { Component, Input, Output, EventEmitter } from '@angular/core';
@Component({
selector: 'my-child',
template: `<p>V1 Childvalue Name: "{{name}}"<br/><input [(ngModel)]="name" (keyup)="onNameChanged()"> <br/><br/>
<p>V2 Childvalue Age: "{{age}}"<br/><input [(ngModel)]="age" (keyup)="onAgeChanged()"> <br/></p>`
})
export class ChildComponent {
@Input() name : string;
@Output() nameChange = new EventEmitter<string>();
@Input() age : string;
@Output() ageChanged = new EventEmitter<string>();
public onNameChanged() {
this.nameChange.emit(this.name);
}
public onAgeChanged() {
this.ageChanged.emit(this.age);
}
}
来源：https://stackoverflow.com/questions/35639650/angular2-two-way-databinding-on-a-component-variable-component-class-propert