What it does
Creates a FormControl
instance from a domain model and binds it to a form control element.
The FormControl
instance will track the value, user interaction, and validation status of the control and keep the view synced with the model. If used within a parent form, the directive will also register itself with the form as a child control.
How to use
This directive can be used by itself or as part of a larger form. All you need is the ngModel
selector to activate it.
It accepts a domain model as an optional @Input. If you have a one-way binding to ngModel
with []
syntax, changing the value of the domain model in the component class will set the value in the view. If you have a two-way binding with [()]
syntax (also known as 'banana-box syntax'), the value in the UI will always be synced back to the domain model in your class as well.
If you wish to inspect the properties of the associated FormControl
(like validity state), you can also export the directive into a local template variable using ngModel
as the key (ex: #myVar="ngModel"
). You can then access the control using the directive's control
property, but most properties you'll need (like valid
and dirty
) will fall through to the control anyway, so you can access them directly. You can see a full list of properties directly available in AbstractControlDirective
.
The following is an example of a simple standalone control using ngModel
:
import {Component} from '@angular/core'; @Component({ selector: 'example-app', template: ` <input [(ngModel)]="name" #ctrl="ngModel" required> <p>Value: {{ name }}</p> <p>Valid: {{ ctrl.valid }}</p> <button (click)="setValue()">Set value</button> `, }) export class SimpleNgModelComp { name: string = ''; setValue() { this.name = 'Nancy'; } }
When using the ngModel
within <form>
tags, you'll also need to supply a name
attribute so that the control can be registered with the parent form under that name.
It's worth noting that in the context of a parent form, you often can skip one-way or two-way binding because the parent form will sync the value for you. You can access its properties by exporting it into a local template variable using ngForm
(ex: #f="ngForm"
). Then you can pass it where it needs to go on submit.
If you do need to populate initial values into your form, using a one-way binding for ngModel
tends to be sufficient as long as you use the exported form's value rather than the domain model's value on submit.
Take a look at an example of using ngModel
within a form:
import {Component} from '@angular/core'; import {NgForm} from '@angular/forms'; @Component({ selector: 'example-app', template: ` <form #f="ngForm" (ngSubmit)="onSubmit(f)" novalidate> <input name="first" ngModel required #first="ngModel"> <input name="last" ngModel> <button>Submit</button> </form> <p>First name value: {{ first.value }}</p> <p>First name valid: {{ first.valid }}</p> <p>Form value: {{ f.value | json }}</p> <p>Form valid: {{ f.valid }}</p> `, }) export class SimpleFormComp { onSubmit(f: NgForm) { console.log(f.value); // { first: '', last: '' } console.log(f.valid); // false } }
npm package: @angular/forms
NgModule: FormsModule
Class Overview
class NgModel { constructor(parent: ControlContainer, validators: Array<Validator|ValidatorFn>, asyncValidators: Array<Validator|AsyncValidatorFn>, valueAccessors: ControlValueAccessor[]) viewModel : any name : string isDisabled : boolean model : any options : {name?: string, standalone?: boolean} update : EventEmitter ngOnChanges(changes: SimpleChanges) ngOnDestroy() : void control : FormControl path : string[] formDirective : any validator : ValidatorFn asyncValidator : AsyncValidatorFn viewToModelUpdate(newValue: any) : void }
Selectors
[ngModel]:not([formControlName]):not([formControl])
Exported as
ngModel
Class Description
Constructor
constructor(parent: ControlContainer, validators: Array<Validator|ValidatorFn>, asyncValidators: Array<Validator|AsyncValidatorFn>, valueAccessors: ControlValueAccessor[])
Class Details
viewModel : any
name : string
isDisabled : boolean
model : any
options : {name?: string, standalone?: boolean}
update : EventEmitter
ngOnChanges(changes: SimpleChanges)
ngOnDestroy() : void
control : FormControl
path : string[]
formDirective : any
validator : ValidatorFn
asyncValidator : AsyncValidatorFn
viewToModelUpdate(newValue: any) : void
exported from @angular/forms/index, defined in @angular/forms/src/directives/ng_model.ts
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