Support for convention-based max length in EF Core

[adampaquette]

• The maximum length is now automatically configured with the use of configurationBuilder.Conventions.AddBaseTypeConventions();.
• I exposed the properties of MaxLengthStringAttribute and MinMaxLengthStringAttribute to be able to grab thoses values from inside the convention builder.
• The doc has been modified

[Andreas-Dorfer]

Hi @adampaquette,
I’m a bit hesitant about the change. I’ll try to give you my reasoning behind that:

Up until now, it’s optional to use the predefined validations in AD.BaseTypes. That means, a library user is free to create his own MaxLengthStringAttribute and everything will continue to work. One possible reason to create your own validations might be to throw custom exceptions with localized error messages.

The implementation of BaseTypeMaxLengthConventions deviates from that principle. The library user has to use the predefined MaxLengthStringAttribute for the convention to work.

I can think of 3 solutions to that problem:

1. Accept that AD.BaseTypes.EFCore works differently and requires the user to use the predefined attributes.
2. Define an interface IMaxLengthStringValidation and change the implementation of BaseTypeMaxLengthConventions to check for the interface.
   I’m not sure where the best place to put IMaxLengthStringValidation would be, but we could put it in an "EFCore" folder in AD.BaseTypes.Core.
3. Don’t provide the BaseTypeMaxLengthConventions in the first place and leave it up to the library user to set up the MaxLength accordingly.

I'm preferring solution 2, but what do you think?