Tracks the value and validation status of an individual form control.

See more...

class FormControl<TValue = any> extends AbstractControl<TValue> {
  new (): FormControl<any>
  defaultValue: TValue
  setValue(value: TValue, options?: { onlySelf?: boolean; emitEvent?: boolean; emitModelToViewChange?: boolean; emitViewToModelChange?: boolean; }): void
  patchValue(value: TValue, options?: { onlySelf?: boolean; emitEvent?: boolean; emitModelToViewChange?: boolean; emitViewToModelChange?: boolean; }): void
  reset(formState?: TValue | FormControlState<TValue>, options?: { onlySelf?: boolean; emitEvent?: boolean; }): void
  getRawValue(): TValue
  registerOnChange(fn: Function): void
  registerOnDisabledChange(fn: (isDisabled: boolean) => void): void

  // inherited from forms/AbstractControl
  constructor(validators: ValidatorFn | ValidatorFn[], asyncValidators: AsyncValidatorFn | AsyncValidatorFn[])
  value: TValue
  validator: ValidatorFn | null
  asyncValidator: AsyncValidatorFn | null
  parent: FormGroup | FormArray | null
  status: FormControlStatus
  valid: boolean
  invalid: boolean
  pending: boolean
  disabled: boolean
  enabled: boolean
  errors: ValidationErrors | null
  pristine: boolean
  dirty: boolean
  touched: boolean
  untouched: boolean
  valueChanges: Observable<TValue>
  statusChanges: Observable<FormControlStatus>
  updateOn: FormHooks
  root: AbstractControl
  setValidators(validators: ValidatorFn | ValidatorFn[]): void
  setAsyncValidators(validators: AsyncValidatorFn | AsyncValidatorFn[]): void
  addValidators(validators: ValidatorFn | ValidatorFn[]): void
  addAsyncValidators(validators: AsyncValidatorFn | AsyncValidatorFn[]): void
  removeValidators(validators: ValidatorFn | ValidatorFn[]): void
  removeAsyncValidators(validators: AsyncValidatorFn | AsyncValidatorFn[]): void
  hasValidator(validator: ValidatorFn): boolean
  hasAsyncValidator(validator: AsyncValidatorFn): boolean
  clearValidators(): void
  clearAsyncValidators(): void
  markAsTouched(opts: { onlySelf?: boolean; } = {}): void
  markAllAsTouched(): void
  markAsUntouched(opts: { onlySelf?: boolean; } = {}): void
  markAsDirty(opts: { onlySelf?: boolean; } = {}): void
  markAsPristine(opts: { onlySelf?: boolean; } = {}): void
  markAsPending(opts: { onlySelf?: boolean; emitEvent?: boolean; } = {}): void
  disable(opts: { onlySelf?: boolean; emitEvent?: boolean; } = {}): void
  enable(opts: { onlySelf?: boolean; emitEvent?: boolean; } = {}): void
  setParent(parent: FormGroup<any> | FormArray<any>): void
  abstract setValue(value: TRawValue, options?: Object): void
  abstract patchValue(value: TValue, options?: Object): void
  abstract reset(value?: TValue, options?: Object): void
  getRawValue(): any
  updateValueAndValidity(opts: { onlySelf?: boolean; emitEvent?: boolean; } = {}): void
  setErrors(errors: ValidationErrors, opts: { emitEvent?: boolean; } = {}): void
  get<P extends string | ((string | number)[])>(path: P): AbstractControl<ɵGetProperty<TRawValue, P>> | null
  getError(errorCode: string, path?: string | (string | number)[]): any
  hasError(errorCode: string, path?: string | (string | number)[]): boolean
}

See also

• AbstractControl

• Reactive Forms Guide

• Usage Notes

Description

This is one of the four fundamental building blocks of Angular forms, along with FormGroup, FormArray and FormRecord. It extends the AbstractControl class that implements most of the base functionality for accessing the value, validation status, user interactions and events.

FormControl takes a single generic argument, which describes the type of its value. This argument always implicitly includes null because the control can be reset. To change this behavior, set nonNullable or see the usage notes below.

See usage examples below.

Further information is available in the Usage Notes...

Constructor

Properties

Methods

// By default, the control will reset to null.
const dog = new FormControl('spot');
dog.reset(); // dog.value is null

// If this flag is set, the control will instead reset to the initial value.
const cat = new FormControl('tabby', {nonNullable: true});
cat.reset(); // cat.value is "tabby"

// A value passed to reset always takes precedence.
const fish = new FormControl('finn', {nonNullable: true});
fish.reset('bubble'); // fish.value is "bubble"

Usage notes

Initializing Form Controls

Instantiate a FormControl, with an initial value.

const control = new FormControl('some value');
console.log(control.value);     // 'some value'

The following example initializes the control with a form state object. The value and disabled keys are required in this case.

const control = new FormControl({ value: 'n/a', disabled: true });
console.log(control.value);     // 'n/a'
console.log(control.status);    // 'DISABLED'

The following example initializes the control with a synchronous validator.

const control = new FormControl('', Validators.required);
console.log(control.value);      // ''
console.log(control.status);     // 'INVALID'

The following example initializes the control using an options object.

const control = new FormControl('', {
   validators: Validators.required,
   asyncValidators: myAsyncValidator
});

The single type argument

FormControl accepts a generic argument, which describes the type of its value. In most cases, this argument will be inferred.

If you are initializing the control to null, or you otherwise wish to provide a wider type, you may specify the argument explicitly:

let fc = new FormControl<string|null>(null);
fc.setValue('foo');

You might notice that null is always added to the type of the control. This is because the control will become null if you call reset. You can change this behavior by setting {nonNullable: true}.

Configure the control to update on a blur event

Set the updateOn option to 'blur' to update on the blur event.

const control = new FormControl('', { updateOn: 'blur' });

Configure the control to update on a submit event

Set the updateOn option to 'submit' to update on a submit event.

const control = new FormControl('', { updateOn: 'submit' });

Reset the control back to a specific value

You reset to a specific form state by passing through a standalone value or a form state object that contains both a value and a disabled state (these are the only two properties that cannot be calculated).

const control = new FormControl('Nancy');

console.log(control.value); // 'Nancy'

control.reset('Drew');

console.log(control.value); // 'Drew'

Reset the control to its initial value

If you wish to always reset the control to its initial value (instead of null), you can pass the nonNullable option:

const control = new FormControl('Nancy', {nonNullable: true});

console.log(control.value); // 'Nancy'

control.reset();

console.log(control.value); // 'Nancy'

Reset the control back to an initial value and disabled

const control = new FormControl('Nancy');

console.log(control.value); // 'Nancy'
console.log(control.status); // 'VALID'

control.reset({ value: 'Drew', disabled: true });

console.log(control.value); // 'Drew'
console.log(control.status); // 'DISABLED'