Angular 4 - “Can't bind to 'ngModel' s

问题:

I'm using Angular 4 and I am getting an error in the console:

Can't bind to 'ngModel' since it isn't a known property of 'input'

How can I resolve this?

回答1:

In order to use two-way data binding for form inputs you need to import the FormsModule package in your Angular module.

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

@NgModule({
    imports: [
         FormsModule      
    ]

---

EDIT

Since there are lot of duplicate questions with the same problem, I am enhancing this answer.

There are two possible reasons

• Missing FormsModule, hence Add this to your Module,

  import { FormsModule } from '@angular/forms';
  
  @NgModule({
      imports: [
          FormsModule      
      ]
  

• Check the syntax/spelling of [(ngModel)] in the input tag

回答2:

This is a right answer. you need to import FormsMoudle

first in app.module.ts

**

import { BrowserModule } from '@angular/platform-browser';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { NgModule  } from '@angular/core';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    FormsModule,
    ReactiveFormsModule ,
    BrowserModule,
    AppRoutingModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

** second in app.component.spec.ts

import { TestBed, async } from '@angular/core/testing';
import { RouterTestingModule } from '@angular/router/testing';
import { AppComponent } from './app.component';
import { FormsModule } from '@angular/forms';
describe('AppComponent', () => {
  beforeEach(async(() => {
    TestBed.configureTestingModule({
      imports: [
        RouterTestingModule,
        FormsModule
      ],
      declarations: [
        AppComponent
      ],
    }).compileComponents();
  }));

Best regards and hope will be helpfull

回答3:

I ran into this error when testing my Angular 6 App with Karma/Jasmine. I had already imported FormsModule in my top-level module. But when I added a new component that used [(ngModel)] my tests began failing. In this case, I needed to import FormsModule in my TestBed TestingModule.

beforeEach(async(() => {
  TestBed.configureTestingModule({
    imports: [
      FormsModule
    ],
    declarations: [
      RegisterComponent
    ]
  })
  .compileComponents();
}));

回答4:

Your ngModel is not working because it's not a part of your NgModule yet.

You have to tell the NgModule that you have authority to use ngModel throughout your app, You can do it by adding FormsModule into your app.module.ts -> imports-> [].

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

@NgModule({

   imports: [ FormsModule ],       // HERE

   declarations: [ AppComponent ],
   bootstrap: [ AppComponent ]
 })

回答5:

Try adding

ngModel in module level

The code is same as the above

回答6:

In app.module.ts add this:

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

@NgModule({
    declarations: [AppComponent],
    imports: [FormsModule],
})

回答7:

    //import form module in app.module.ts.

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


@NgModule({
  declarations: [
    AppComponent,
    ContactsComponent
  ],
  imports: [
    BrowserModule,HttpModule,FormsModule     //Add here form  module
  ],
  providers: [],
  bootstrap: [AppComponent]
})

    //In html
    <input type="text" name="last_name" [(ngModel)]="last_name" [ngModelOptions]="{standalone: true}" class="form-control">

回答8:

import { FormsModule } from '@angular/forms'; //<<<< import it here

BrowserModule, FormsModule //<<<< and here

So simply looks for app.module.ts or another module file and make sure you have FormsModule imported in...