Add a way to set new default values to reactive form controls

[DerChris173]

Which @angular/* package(s) are relevant/related to the feature request?

forms

Description

For typical CRUD operations, it's often required to

• reset the dialog to its initial state
• query if a particular FormControl has a value that's different than the original one.

The defaultValue/reset() Feature is quite suitable for this. Unfortunately, there's no way to change the defaultValue, e.g. once the user performs a "Save action".

Proposed solution

I propose to enhance the Reactive FormControl API with the following methods:

• setDefaultValue(newDefaultValue: TValue): Updates the defaultValue of the FormControl to newDefaultValue. Calls to the reset() operation in particular will use this new defaultValue.
• setCurrentValuesAsDefault(): Convenience method for formControl.setDefaultValue(formControl.getRawValue()).

I'd be happy to develop and raise a PR for this feature.

Alternatives considered

Another alternative would be to build entirely new FormControls if new default values are required. However, this might be less convenient and has issues currently with 2-way-data-binding, I believe.

[DerChris173]

Thank you for looking into this issue!
I wasn't very clear when I wrote the this issue, but I'm talking about reactive forms, where ngModel is not used.

[danieljancar]

Hey @DerChris173,
I agree this feature would be quite beneficial. Below is a simplified use case I came across:

import { FormControl } from '@angular/forms';

class ExampleComponent {
  myFormControl: FormControl;

  constructor() {
    this.myFormControl = new FormControl('initialValue'); // Initial default value
  }

  updateDefaultValue() {
    const newDefaultValue = 'updatedValue';
    this.myFormControl.setDefaultValue(newDefaultValue); // Proposed method to update default value
  }

  resetToDefaultValue() {
    this.myFormControl.reset(); // Resets to 'updatedValue', if updateDefaultValue() was called
  }
}

Let's say a user updates their profile name from 'John Doe' (default) to 'Jane Smith'. Currently, reopening the form for more edits would show 'John Doe' again. The suggested setDefaultValue method would allow the form to show 'Jane Smith' as the default, aligning with the latest data and improving UX.

[DerChris173]

Hi @alxhub! Thank you for looking at this ticket! I saw that you adjusted the milestone. Does it mean that such a feature would be accepted? I could work on a PR. I already signed the CLA.

[danieljancar]

@DerChris173, this feature request would either require a community vote or the Angular teams internal agreement on this. 😉 I could assist you with developing this feature, if continued.

[angular-robot]

This feature request is now candidate for our backlog! In the next phase, the community has 60 days to upvote. If the request receives more than 20 upvotes, we'll move it to our consideration list.

You can find more details about the feature request process in our documentation.

[cluxig]

I would prefer an additional option on form.setValue(newValue, true) in case of the form update is used as new default.

[JeanMeche]

Without expanding too much the API surface, we could remove the readonly from FormControl.defaultValue to achieve this feature.

Would there be any unwanted side effects if we do this ?