fix: use built-in Angular email validator for eperson form

[pzlakowski]

References

Fixes Not able to create an account with an email containing uppercase letters from eperson form #4338

Description

I have replaced regex pattern to use built-in one from Angular when we create e-person via form.

I think we should refrain from using our own regex when Angular provides one similar. Unless there is a reason which I do not know about yet.

e.g. issue shows to use pattern from src/app/register-email-form/register-email-form.component.ts

^[a-zA-Z0-9.!#$%&\'*+\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$

where Angular tries to adhere to WHATWG spec too https://github.com/angular/angular/blob/4755bbd94964f27921ec203fc1a9233a01c84792/packages/forms/src/validators.ts#L151

Angular adds 3 different constraints compared to WHATWG:

• Disallow local-part to begin or end with a period (.).
• Disallow local-part length to exceed 64 characters.
• Disallow total address length to exceed 254 characters.

Instructions for Reviewers

List of changes in this PR:

• I have replaced pattern to use built-in email validator provided by Angular
• I have updated test to include uppercased case

Steps test this PR:

1. Visit http://localhost:4000/access-control/epeople/create
2. Fill a form with uppercased e-mail e.g. TEST@example.com
3. Create account and should success

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[alanorth]

Thanks @pzlakowski. I agree that we should not be maintaining our own validation logic for something common like emails when Angular provides one that is likely better tested.

Having said that, I tested this on DSpace 8 and noticed that the email TEST@example is valid with this PR. I'm surprised that Angular's validator would consider that valid. Is the behavior different in DSpace 9/main?

[pzlakowski]

@alanorth this is desired behaviour https://angular.dev/api/forms/Validators#email given WHATWG spec. Angular recommends to use custom regex pattern if business needs are different. There should be no difference.

I think if we wanted to support to require top-level domain we could use regex like this:

^(?=.{1,254}$)(?=.{1,64}@)[-!#$%&'*+/0-9=?A-Z^_`a-z{|}~]+(\.[-!#$%&'*+/0-9=?A-Z^_`a-z{|}~]+)*@[A-Za-z0-9]([A-Za-z0-9-]{0,61}[A-Za-z0-9])?(\.[A-Za-z0-9]([A-Za-z0-9-]{0,61}[A-Za-z0-9])?)+$

This is derived from Angular regex, simply swapped from * to + at the end to enforce it.

[alanorth]

Thanks @pzlakowski. I don't understand the upstream use case of allowing test@example, but perhaps I don't need to! If we can use the Angular email validator to reduce custom code we need to maintain, and in that process gain support for addresses like TEST@example.com then I am in support of this. Also, as this only affects the "create eperson" functionality that is only accessible by admins I think the negative impact is low.

+1 by me by review and testing.

[saschaszott]

Which email address validation is performed by the backend? Both validation rules (of frontend and backend) should be identical. Do we need to adapt the backend validation rule?