@angular/forms

FormBuilder

Class

Creates an AbstractControl from a user-specified configuration.

class FormBuilder {
}

Creates an AbstractControl from a user-specified configuration.

The FormBuilder provides syntactic sugar that shortens creating instances of a FormControl, FormGroup, or FormArray. It reduces the amount of boilerplate needed to build complex forms.

nonNullable

NonNullableFormBuilder

Returns a FormBuilder in which automatically constructed FormControl elements have {nonNullable: true} and are non-nullable.

Constructing non-nullable controls

When constructing a control, it will be non-nullable, and will reset to its initial value.

          
            let nnfb = new FormBuilder().nonNullable;let name = nnfb.control('Alex'); // FormControl<string>name.reset();console.log(name); // 'Alex'

Constructing non-nullable groups or arrays

When constructing a group or array, all automatically created inner controls will be non-nullable, and will reset to their initial values.

          
            let nnfb = new FormBuilder().nonNullable;let name = nnfb.group({who: 'Alex'}); // FormGroup<{who: FormControl<string>}>name.reset();console.log(name); // {who: 'Alex'}

Constructing nullable fields on groups or arrays

It is still possible to have a nullable field. In particular, any FormControl which is already constructed will not be altered. For example:

          
            let nnfb = new FormBuilder().nonNullable;// FormGroup<{who: FormControl<string|null>}>let name = nnfb.group({who: new FormControl('Alex')});name.reset(); console.log(name); // {who: null}

Because the inner control is constructed explicitly by the caller, the builder has no control over how it is created, and cannot exclude the null.

group

2 overloads

Constructs a new FormGroup instance. Accepts a single generic argument, which is an object containing all the keys and corresponding inner control types.

@paramcontrolsT

A collection of child controls. The key for each child is the name under which it is registered.

@paramoptionsAbstractControlOptions

Configuration options object for the FormGroup. The object should have the AbstractControlOptions type and might contain the following fields:

validators: A synchronous validator function, or an array of validator functions.
asyncValidators: A single async validator or array of async validator functions.
updateOn: The event upon which the control should be updated (options: 'change' | 'blur' | submit').

@returnsFormGroup<{ [K in keyof T]: ɵElement<T[K], null>; }>

Constructs a new FormGroup instance.

@deprecated

This API is not typesafe and can result in issues with Closure Compiler renaming. Use the FormBuilder#group overload with AbstractControlOptions instead. Note that AbstractControlOptions expects validators and asyncValidators to be valid validators. If you have custom validators, make sure their validation function parameter is AbstractControl and not a sub-class, such as FormGroup. These functions will be called with an object of type AbstractControl and that cannot be automatically downcast to a subclass, so TypeScript sees this as an error. For example, change the (group: FormGroup) => ValidationErrors|null signature to be (group: AbstractControl) => ValidationErrors|null.

@paramcontrols{ [key: string]: any; }

A record of child controls. The key for each child is the name under which the control is registered.

@paramoptions{ [key: string]: any; }

Configuration options object for the FormGroup. The legacy configuration object consists of:

validator: A synchronous validator function, or an array of validator functions.
asyncValidator: A single async validator or array of async validator functions Note: the legacy format is deprecated and might be removed in one of the next major versions of Angular.

@returnsFormGroup<any>

record

FormRecord<ɵElement<T, null>>

Constructs a new FormRecord instance. Accepts a single generic argument, which is an object containing all the keys and corresponding inner control types.

@paramcontrols{ [key: string]: T; }

A collection of child controls. The key for each child is the name under which it is registered.

@paramoptionsAbstractControlOptions

Configuration options object for the FormRecord. The object should have the AbstractControlOptions type and might contain the following fields:

validators: A synchronous validator function, or an array of validator functions.
asyncValidators: A single async validator or array of async validator functions.
updateOn: The event upon which the control should be updated (options: 'change' | 'blur' | submit').

@returnsFormRecord<ɵElement<T, null>>

control

4 overloads

@deprecated

Use nonNullable instead.

@paramformStateT | FormControlState<T>

@paramoptsFormControlOptions & { initialValueIsDefault: true; }

@returnsFormControl<T>

@paramformStateT | FormControlState<T>

@paramoptsFormControlOptions & { nonNullable: true; }

@returnsFormControl<T>

@deprecated

When passing an options argument, the asyncValidator argument has no effect.

@paramformStateT | FormControlState<T>

@paramoptsFormControlOptions

@paramasyncValidatorAsyncValidatorFn | AsyncValidatorFn[]

@returnsFormControl<T>

@paramformStateT | FormControlState<T>

@paramvalidatorOrOptsValidatorFn | FormControlOptions | ValidatorFn[]

@paramasyncValidatorAsyncValidatorFn | AsyncValidatorFn[]

@returnsFormControl<T>

array

FormArray<ɵElement<T, null>>

Constructs a new FormArray from the given array of configurations, validators and options. Accepts a single generic argument, which is the type of each control inside the array.

@paramcontrolsT[]

An array of child controls or control configs. Each child control is given an index when it is registered.

@paramvalidatorOrOptsValidatorFn | AbstractControlOptions | ValidatorFn[]

A synchronous validator function, or an array of such functions, or an AbstractControlOptions object that contains validation functions and a validation trigger.

@paramasyncValidatorAsyncValidatorFn | AsyncValidatorFn[]

A single async validator or array of async validator functions.

@returnsFormArray<ɵElement<T, null>>