Data Annotation Extensions

[mottaghipour]

Summary

To complete minimal validations(#30666) we should have some data annotations extensions.
I have an idea and I want to know if you agree with it to apply it?

Motivation and goals

The idea is to quickly validate objects

Examples

Validation extensions:

public static class DataAnnotationsExtensions
{
    public static Tuple<bool, ValidationResult> Validate(this object model) { ... }
    public static Tuple<bool, ICollection<ValidationResult>> ValidateAllProperties(this object model) { ... }
}

Minimal Apis:

app.MapPost("/todos", async (Todo todo) =>
{
    var (isValid, result) = todo.Validate();
    
    if (!isValid)
    {
        ...
    }
});

@halter73 @davidfowl
I think this idea is good but I don't know which project or folder for this methods.
If you are agree I implement this extensions and create pull request.

[davidfowl]

These aren't tied to ASP.NET. This is a generic data annotations requests for recursive validation. Also extension methods on object are not great. I would prefer to see a static method here Validator class.

cc @DamianEdwards @ajcvickers

[mottaghipour]

I agree with you, I have thought about this before.
If objects inherits from IValidatable, This is how we implement it:

public interface IValidatable
{
    Tuple<bool, ICollection<ValidationResult>> Validate();
}

We can implement abstarct class Validatable for defualt base validations, users can customize IValidatable for another validation packages, as the same way if user want use defualt validation with validation attrs:

public class TodoCommand : Validatable
{
    // [ValidationAttr]
    // Prop ...
}

I guess maybe the user wanted to use other packages for validation, they can customize them or even package development teams can create a way to customize it.

If we go this way, we can change the whole structure of requests and use IValidatable everywhere, for example ApiController can validate model with Validate method and object changes state IsValid This also avoids over-validation and finds a clear framework.
@davidfowl