Set default for DisplayFormatAttribute.ConvertEmptyStringToNull to false in .NET Core

Question

I want to make [DisplayFormat(ConvertEmptyStringToNull = false)] the default behaviour for my fields in an ASP.NET Core web application.

Related questions are for .NET Framework, and I am unsure on how to proceed with .NET Core

public class EmptyStringAllowedModelMetadataProvider : DefaultModelMetadataProvider
{
    public EmptyStringAllowedModelMetadataProvider(ICompositeMetadataDetailsProvider detailsProvider) : base(detailsProvider)
    {
    }

    public EmptyStringAllowedModelMetadataProvider(ICompositeMetadataDetailsProvider detailsProvider, IOptions<MvcOptions> optionsAccessor) : base(detailsProvider, optionsAccessor)
    {
    }

    public override ModelMetadata GetMetadataForType(Type modelType)
    {
        if (modelType != typeof(string)) return base.GetMetadataForType(modelType);
        var identity = ModelMetadataIdentity.ForType(modelType);
        var details = CreateTypeDetails(identity);
        var context = new DisplayMetadataProviderContext(identity, details.ModelAttributes);
        DetailsProvider.CreateDisplayMetadata(context);
        details.DisplayMetadata = context.DisplayMetadata;
        details.DisplayMetadata.ConvertEmptyStringToNull = false;
        return CreateModelMetadata(details);
    }
}

score 1 · Accepted Answer · answered Jun 08 '22 at 08:23

You can refer to the following way, it works fine:

CustomMetadataProvider:

public class CustomMetadataProvider : IMetadataDetailsProvider, IDisplayMetadataProvider
    {
        public void CreateDisplayMetadata(DisplayMetadataProviderContext context)
        {
            if (context.Key.MetadataKind == ModelMetadataKind.Property)
            {
                context.DisplayMetadata.ConvertEmptyStringToNull = false;
            }
        }
}

registration service：

services.AddMvc()
             .AddMvcOptions(options => options.ModelMetadataDetailsProviders.Add(new CustomMetadataProvider()));

Test Result:

Will validate on Tuesday, blocked by some other tasks right now. Thanks for the response! — TeamDman, Jun 12 '22 at 20:42

Set default for DisplayFormatAttribute.ConvertEmptyStringToNull to false in .NET Core

1 Answers1