Adding support for FluentValidations and swagger schema.

I wish to register FluentValidation rules, so that they show up in swagger schema. Given the sample code below:

public class Validator : AbstractValidator<ClosureScheduleCommand> 
{
    public Validator()
    {
        RuleFor(x => x.Warehouse).NotEmpty();
    }
}

We should be able to correctly mark the property as required. Example of the wanted schema presentation in Swagger The required field is marked by a red asterix. In this example i relied on the attribute [JsonRequired]

Similar implementations in MVC aspnetcore 3.1:

• https://github.com/micro-elements/MicroElements.Swashbuckle.FluentValidation.WebApi
• https://github.com/zymlabs/nswag-fluentvalidation

[wjax]

After some discussion with @dj-nitehawk we will keep the current support for a single validator against the request type of the endpoint. We will not make complex things injecting base validators automatically that could break the surface api or make things too complex.

Of course the requestDto can use inheritance and it will play nice with both the validator and the swagger support.

So, in case anyone needs to reuse a validator from a base type, he/she can use inheritance in the validator like this:

public class Request : BaseIdentifier
{
    public string? NullableIdentifier { get; set; }
    public string? Message { get; set; }
}

public class BaseIdentifier
{
    public string Identifier { get; set; }
    public string baseMessage { get; set; }
}

public class RequestValidator : BaseIdentifierValidator<Request>
{
    public RequestValidator()
    {
        RuleFor(x => x.Identifier).NotEmpty();
        RuleFor(x => x.NullableIdentifier).NotEmpty();
        RuleFor(x => x.Message).Length(3, 100);
    }
}

public class BaseIdentifierValidator<TDto> : Validator<TDto> where TDto : BaseIdentifier
{
    public BaseIdentifierValidator()
    {
        RuleFor(x => x.baseMessage).Length(10, 100);
    }
}

[andreas-soroko]

I am also highly interested in that feature 👍🏼