dart_schema_builder/lib/src/formats.dart has bad email regex

[RandalSchwartz]

Describe the bug
dart_schema_builder/lib/src/formats.dart has an incorrect regex for email.

To Reproduce
View the source:

'email': (value) {
    return RegExp(
      r"^[a-zA-Z0-9.a-zA-Z0-9.!#$%&'*+-/=?^_`{|}~-]+@[a-zA-Z0-9]+\.[a-zA-Z]+",
    ).hasMatch(value);
  },

Expected behavior
No, please don't use this regex to validate email. It's wrong. The shortest regex to validate an RFC822 email address is about 2400 characters, and is given in https://www.ex-parrot.com/pdw/Mail-RFC822-Address.html. Anything shorter is WRONG, unless you're using a grammar, as package:email_validator properly does. Use that for Dart/Flutter please.

Additional context
Common mistake, because most people don't know the facts about email. :)

[yjbanov]

Yeah. Another problem is that formatValidators is a global static mutable map. We probably want a more robust API, with proper scoping and dependency injection capabilities. The default set of validators should probably be limited to things that do not require large external dependencies like email_validator.

[ditman]

There's this related incoming PR, but it doesn't address @RandalSchwartz's request:

#298

[RandalSchwartz]

Yeah. Another problem is that formatValidators is a global static mutable map. We probably want a more robust API, with proper scoping and dependency injection capabilities. The default set of validators should probably be limited to things that do not require large external dependencies like email_validator.

It'd probably be OK to have an "example" that consumes email_validator... would be a good example of providing custom additional validators.

[RandalSchwartz]

There's this related incoming PR, but it doesn't address @RandalSchwartz's request:

#298

Yeah, it's actually heading in the wrong direction, thinking a regex that short can still be called "correct".