What it does
Tracks the value and validity state of a group of FormControl
instances.
A FormGroup
aggregates the values of each child FormControl
into one object, with each control name as the key. It calculates its status by reducing the statuses of its children. For example, if one of the controls in a group is invalid, the entire group becomes invalid.
FormGroup
is one of the three fundamental building blocks used to define forms in Angular, along with FormControl
and FormArray
.
How to use
When instantiating a FormGroup
, pass in a collection of child controls as the first argument. The key for each child will be the name under which it is registered.
Example
const form = new FormGroup({ first: new FormControl('Nancy', Validators.minLength(2)), last: new FormControl('Drew'), }); console.log(form.value); // {first: 'Nancy', last; 'Drew'} console.log(form.status); // 'VALID'
You can also include group-level validators as the second arg, or group-level async validators as the third arg. These come in handy when you want to perform validation that considers the value of more than one child control.
Example
const form = new FormGroup({ password: new FormControl('', Validators.minLength(2)), passwordConfirm: new FormControl('', Validators.minLength(2)), }, passwordMatchValidator); function passwordMatchValidator(g: FormGroup) { return g.get('password').value === g.get('passwordConfirm').value ? null : {'mismatch': true}; }
-
npm package:
@angular/forms
Class Overview
class FormGroup { constructor(controls: {[key: string]: AbstractControl}, validator?: ValidatorFn, asyncValidator?: AsyncValidatorFn) controls : {[key: string]: AbstractControl} registerControl(name: string, control: AbstractControl) : AbstractControl addControl(name: string, control: AbstractControl) : void removeControl(name: string) : void setControl(name: string, control: AbstractControl) : void contains(controlName: string) : boolean setValue(value: {[key: string]: any}, {onlySelf}?: {onlySelf?: boolean}) : void patchValue(value: {[key: string]: any}, {onlySelf}?: {onlySelf?: boolean}) : void reset(value?: any, {onlySelf}?: {onlySelf?: boolean}) : void getRawValue() : Object }
Class Description
Constructor
constructor(controls: {[key: string]: AbstractControl}, validator?: ValidatorFn, asyncValidator?: AsyncValidatorFn)
Class Details
controls : {[key: string]: AbstractControl}
registerControl(name: string, control: AbstractControl) : AbstractControl
Registers a control with the group's list of controls.
This method does not update value or validity of the control, so for most cases you'll want to use addControl
instead.
addControl(name: string, control: AbstractControl) : void
Add a control to this group.
removeControl(name: string) : void
Remove a control from this group.
setControl(name: string, control: AbstractControl) : void
Replace an existing control.
contains(controlName: string) : boolean
Check whether there is an enabled control with the given name in the group.
It will return false for disabled controls. If you'd like to check for existence in the group only, use get
instead.
setValue(value: {[key: string]: any}, {onlySelf}?: {onlySelf?: boolean}) : void
Sets the value of the FormGroup
. It accepts an object that matches the structure of the group, with control names as keys.
This method performs strict checks, so it will throw an error if you try to set the value of a control that doesn't exist or if you exclude the value of a control.
const form = new FormGroup({ first: new FormControl(), last: new FormControl() }); console.log(form.value); // {first: null, last: null} form.setValue({first: 'Nancy', last: 'Drew'}); console.log(form.value); // {first: 'Nancy', last: 'Drew'}
patchValue(value: {[key: string]: any}, {onlySelf}?: {onlySelf?: boolean}) : void
Patches the value of the FormGroup
. It accepts an object with control names as keys, and will do its best to match the values to the correct controls in the group.
It accepts both super-sets and sub-sets of the group without throwing an error.
const form = new FormGroup({ first: new FormControl(), last: new FormControl() }); console.log(form.value); // {first: null, last: null} form.patchValue({first: 'Nancy'}); console.log(form.value); // {first: 'Nancy', last: null}
reset(value?: any, {onlySelf}?: {onlySelf?: boolean}) : void
Resets the FormGroup
. This means by default:
- The group and all descendants are marked
pristine
- The group and all descendants are marked
untouched
- The value of all descendants will be null or null maps
You can also reset to a specific form state by passing in a map of states that matches the structure of your form, with control names as keys. The state can be a standalone value or a form state object with both a value and a disabled status.
this.form.reset({first: 'name', last; 'last name'}); console.log(this.form.value); // {first: 'name', last: 'last name'}
- OR -
this.form.reset({ first: {value: 'name', disabled: true}, last: 'last' }); console.log(this.form.value); // {first: 'name', last: 'last name'} console.log(this.form.get('first').status); // 'DISABLED'
getRawValue() : Object
The aggregate value of the FormGroup
, including any disabled controls.
If you'd like to include all values regardless of disabled status, use this method. Otherwise, the value
property is the best way to get the value of the group.
exported from @angular/forms/index, defined in @angular/forms/src/model.ts
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