如何将 FluentValidation 与 MetadataTypeAttribute 一起使用？

Question

I'm developing ASP.NET MVC appliation. I've found Fluent Validation great validation tool and it works, but with my current architecture it has one drawback. The validator does not care about Metadata. I'm using Metadata on seperate class for clarity.

Model

[MetadataType(typeof(DocumentEditMetadata))]
[Validator(typeof(DocumentValidator))]
public class DocumentEditModel
{
    public string DocumentNumber { get; set; }
    (etc...)
}

Metadata Model

public class DocumentEditMetadata
{
    [Required]
    [StringLength(50)]
    [Display(ResourceType = typeof(Label), Name = "DocumentNumber")]
    public string DocumentNumber { get; set; }
    (etc...)
}

Can anyone point a solution? I need data annotations for localization of labels (hence the DisplayAttribute).

Answer 1

Think you need to write your own Display name resolver for fluent validation (guess this should be placed in your global.asax).

Caution

This solution is only trying to resolve the display name .

Your other "validation" attributes ( Required , StringLength ) should no more be used, as you will manage that with FluentValidation.

ValidatorOptions.DisplayNameResolver = (type, memberInfo, expression) =>
{
      //this will get in this case, "DocumentNumber", the property name. 
      //If we don't find anything in metadata / resource, that what will be displayed in the error message.
      var displayName = memberInfo.Name;
      //we try to find a corresponding Metadata type
      var metadataType = type.GetCustomAttribute<MetadataTypeAttribute>();
      if (metadataType != null)
      {
           var metadata = metadataType.MetadataClassType;
           //we try to find a corresponding property in the metadata type
           var correspondingProperty = metadata.GetProperty(memberInfo.Name);
           if (correspondingProperty != null)
           {
                //we try to find a display attribute for the property in the metadata type
                var displayAttribute = correspondingProperty.GetCustomAttribute<DisplayAttribute>();
                if (displayAttribute != null)
                {
                     //finally we got it, try to resolve the name !
                     displayName = displayAttribute.GetName();
                }
          }
      }
      return displayName ;
};

Personal point of view

By the way, if you just use Metadata classes for clarity , don't use them ! It may be a solution if you have no choice (when entity classes are generated from an edmx and you really want to manage the display names this way), but I would really avoid them if it's not necessary.

Answer 2

public class CreateHireViewModel 
{
    [Display(Name = nameof(CreateHireViewModel.Title), ResourceType = typeof(Resource.HireResource.Hire))]
    public string Title { get; set; }
}

public class CreateHireViewModelValidator : AbstractValidator<CreateHireViewModel>
{
    public CreateHireViewModelValidator(IStringLocalizer<Resource.HireResource.Hire> l)
    {
        RuleFor(x => x.Title).NotEmpty().WithName(l[nameof(CreateHireViewModel.Title)]); 
        
        RuleFor(x => x.Title).Length(3, 50).WithName(l[nameof(CreateHireViewModel.Title)]);

    }
}