Angular 2 使用 ngModel 的双向绑定不起作用

Question

Can't bind to 'ngModel' since it isn't a know property of the 'input' element and there are no matching directives with a corresponding property

Note: im using alpha.31

import { Component, View, bootstrap } from 'angular2/angular2'

@Component({
    selector: 'data-bind'
})
@View({
    template:`
        <input id="name" type="text" 
            [ng-model]="name" 
            (ng-model)="name = $event" />
        {{ name }}
    ` 
})
class DataBinding { 
    name: string;

    constructor(){
        this.name = 'Jose';
    }
}

bootstrap(DataBinding);

Answer 1

Angular has released its final version on 15th of September. Unlike Angular 1 you can use ngModel directive in Angular 2 for two way data binding, but you need write it in a bit different way like [(ngModel)] ( Banana in a box syntax ). Almost all angular2 core directives doesn't support kebab-case now instead you should use camelCase .

Now ngModel directive belongs to FormsModule , that's why you should import the FormsModule from @angular/forms module inside imports metadata option of AppModule (NgModule). Thereafter you can use ngModel directive inside on your page.

app/app.component.ts

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

@Component({
  selector: 'my-app',
  template: `<h1>My First Angular 2 App</h1>
    <input type="text" [(ngModel)]="myModel"/>
    {{myModel}}
  `
})
export class AppComponent { 
  myModel: any;
}

app/app.module.ts

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { AppComponent }   from './app.component';

@NgModule({
  imports:      [ BrowserModule, FormsModule ], //< added FormsModule here
  declarations: [ AppComponent ],
  bootstrap:    [ AppComponent ]
})

export class AppModule { }

app/main.ts

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { AppModule } from './app.module';

const platform = platformBrowserDynamic();
platform.bootstrapModule(AppModule);

Demo Plunkr

Answer 2

Key Points:

1. ngModel in angular2 is valid only if the FormsModule is available as a part of your AppModule.

2. ng-model is syntatically wrong.

3. square braces [..] refers to the property binding.
4. circle braces (..) refers to the event binding.
5. when square and circle braces are put together as [(..)] refers two way binding, commonly called banana box.

So, to fix your error.

Step 1: Importing FormsModule

import {FormsModule} from '@angular/forms'

Step 2: Add it to imports array of your AppModule as

imports :[ ... , FormsModule ]

Step 3: Change ng-model as ngModel with banana boxes as

 <input id="name" type="text" [(ngModel)]="name" />

Note: Also, you can handle the two way databinding separately as well as below

<input id="name" type="text" [ngModel]="name" (ngModelChange)="valueChange($event)"/>

valueChange(value){

}

Answer 3

就我而言，我的输入元素上缺少“名称”属性。

Answer 4

As per Angular2 final, you do not even have to import FORM_DIRECTIVES as suggested above by many. However, the syntax has been changed as kebab-case was dropped for the betterment.

Just replace ng-model with ngModel and wrap it in a box of bananas . But you have spilt the code into two files now:

app.ts:

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

@Component({
  selector: 'ng-app',
  template: `
    <input id="name" type="text" [(ngModel)]="name"  />
    {{ name }}
  `
})
export class DataBindingComponent {
  name: string;

  constructor() {
    this.name = 'Jose';
  }
}

app.module.ts:

import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { BrowserModule } from '@angular/platform-browser';
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { DataBindingComponent } from './app'; //app.ts above

@NgModule({
  declarations: [DataBindingComponent],
  imports:      [BrowserModule, FormsModule],
  bootstrap:    [DataBindingComponent]
})
export default class MyAppModule {}

platformBrowserDynamic().bootstrapModule(MyAppModule);

Answer 5

The answer that helped me: The directive [(ngModel)]= not working anymore in rc5

To sum it up: input fields now require property name in the form.

Answer 6

In the app.module.ts

import { FormsModule } from '@angular/forms';

Later in the @NgModule decorator's import:

@NgModule({
imports: [
BrowserModule,
FormsModule
]

})

Answer 7

Angular 2 Beta

This answer is for those who use Javascript for angularJS v.2.0 Beta.

To use ngModel in your view you should tell the angular's compiler that you are using a directive called ngModel .

How?

To use ngModel there are two libraries in angular2 Beta, and they are ng.common.FORM_DIRECTIVES and ng.common.NgModel .

Actually ng.common.FORM_DIRECTIVES is nothing but group of directives which are useful when you are creating a form. It includes NgModel directive also.

app.myApp = ng.core.Component({
    selector: 'my-app',
    templateUrl: 'App/Pages/myApp.html',
    directives: [ng.common.NgModel] // specify all your directives here
}).Class({
    constructor: function () {
        this.myVar = {};
        this.myVar.text = "Testing";
    },

});

Answer 8

Note : To allow the ngModel exists Independently inside reactive form, we have to use ngModelOptions as follows:

 [ngModelOptions]="{ standalone: true }"

For Example :

 <mat-form-field appearance="outline" class="w-100">
            <input
              matInput 
              [(ngModel)]="accountType"
              [ngModelOptions]="{ standalone: true }"
            />
 </mat-form-field>

Answer 9

These things are missing/ Wrong:

• Import FormsModule in imports array of module (ngModel requires FormsModule)
• ngModel is written as: [(ngModel)]="modelName"

This way, It will work fine!

Answer 10

instead of ng-model you can use this code:

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

@Component({
  selector: 'my-app',
  template: `<input #box (keyup)="0">
    <p>{{box.value}}</p>`,
})
export class AppComponent  {}

inside your app.component.ts

Answer 11

Add below code to following files.

app.component.ts

<input type="text" [(ngModel)]="fname" >
{{fname}}
export class appcomponent {
fname:any;
}

app.module.ts

import {FormsModule} from '@angular/forms';
@NgModule({
imports: [ BrowserModule,FormsModule ],
declarations: [ AppComponent],
bootstrap:    [ AppComponent ]
})

Hope this helps

Answer 12

在您的 AppModule 中导入 FormsModule 以使用两种方式绑定 [(ngModel)]

Answer 13

For newer versions of Angular:

1. -write it as [(ngModel)] = yourSearch

2. declare a empty variable(property) named as yourSearch in .ts file

3. add FormsModule in app.module.ts file from - @angular/forms;

4. if your application is running, then restart it as you made changes in its module.ts file

Answer 14

if you are using lazy loading module, you need to import ngModule and formModule in the current module. example:

//shared.module.ts
import { NgModule } from '@angular/core';
import {FormsModule} from '@angular/forms'

imports: [
    FormsModule,]

Answer 15

Adding a name property solved the problem for me