Expose tree-shakable validator functions via public API

[penfold]

🐞 bug report

Affected Package

@angular/forms

Is this a regression?

No

Description

Following #41189 in NG 11.2.6. I was expecting to be able to use the new validator functions directly.

e.g. use requiredValidator instead of Validators.required.

After a bit of digging it would seem that they are marked for internal use (?).

In the forms.d.ts, I expected ɵangular_packages_forms_forms_bb to be requiredValidator.

/**
 * @description
 * Provider which adds `RequiredValidator` to the `NG_VALIDATORS` multi-provider list.
 */
export declare const ɵangular_packages_forms_forms_bb: StaticProvider;

/**
 * @description
 * Provider which adds `CheckboxRequiredValidator` to the `NG_VALIDATORS` multi-provider list.
 */
export declare const ɵangular_packages_forms_forms_bc: StaticProvider;

/**
 * @description
 * Provider which adds `EmailValidator` to the `NG_VALIDATORS` multi-provider list.
 */
export declare const ɵangular_packages_forms_forms_bd: any;

/**
 * @description
 * Provider which adds `MinLengthValidator` to the `NG_VALIDATORS` multi-provider list.
 */
export declare const ɵangular_packages_forms_forms_be: any;

/**
 * @description
 * Provider which adds `MaxLengthValidator` to the `NG_VALIDATORS` multi-provider list.
 */
export declare const ɵangular_packages_forms_forms_bf: any;

🔬 Minimal Reproduction

N/A

🔥 Exception or Error

N/A

🌍 Your Environment

Angular Version:
11.2.6

[penfold]

This is when using Reactive form validation as documented: https://angular.io/guide/reactive-forms#validating-form-input

[penfold]

Do the method summary comments just need @publicapi to be added?

[JoostK]

The changes in #41189 were to allow internal usages of individual validators to not also pull in all of Validators. It was not about extending the public API to allow external packages to do the same. Extending API could not have been done in a patch release and it would require a strategy for possibly deprecating the static methods on Validators.

[penfold]

@JoostK Thank you for your explanation. This release would only give a bundle size benefit to people using Template forms. It would be great if it can be extended to my use case using Reactive forms.

On a side note, it's good to see forms in general gettings some attention from the NG team. Thank you.

[AndrewKushnir]

@penfold thanks for creating this ticket. As Joost mentioned above, the goal of #41189 was to perform internal refactoring to make validators code tree-shakable without changing the API surface.

We'll consider adding these standalone validator functions to the public API, but that would require additional discussions/decisions like deprecating Validators class (or at least stop recommending it in docs and use tree-shakable functions instead) and potentially creating a new entry-point in @angular/forms for more ergonomic (and similar to what we have now) usage like this:

import * as Validators from '@angular/forms/validators';
...
const control = new FormControl('', Validators.required);

We'll keep this ticket updated once there is any new information available.

[splincode]

@AndrewKushnir great idea (migration with schematics, if needed)

import * as Validators from '@angular/forms/validators';
...
const control = new FormControl('', Validators.required);

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