It's a little old but maybe https://world.optimizely.com/blogs/Anders-Hattestad/Dates/2015/2/extending-the-hyperlink-with-custom-field/ will point you in the right direction

Thanks Scott -- I did see this and gave it a shot, but I ran into the same issues others in the comments did and can't get the modal to render with the supplied code since it's based on earlier version of the CMS. 

Hey Ian, I've just posted a new version of that code on my blog, which works for version 11 of the CMS. It should work for version 12 too but I haven't test it yet. 

https://ynze.hashnode.dev/extending-the-hyperlink-editor-in-version-11

Thanks Ynze, this is great! 

Hi Ian,

Did you start implementing this? I'd imagine itcould get a little tricky for a few reasons (and depending on your precise needs):

1. You'd likely have to do some heavy Dojo customisation, depending on how you wanted editors to be able to enable data attributes
2. The URL property is backed by a string, so you'd have to persist everything as a single string in the database
3. You'd need to split the URL property above when rendering to extract the data attributes out

I also did a blog about customising this, specifically covering adding a telephone link option: https://jakejon.es/blog/adding-a-telephone-link-option-to-the-episerver-link-editor

I'd probably advise against doing this, but if you're already started I'd really like to hear what your approach is 😊

Hi Jake--

I have, but I've found another route that doesn't involve any Dojo customization. Essentially, I wanted to allow editors to select specific types of blocks (any inheriting `IModalContentBlock`) as a link, instead of a page. In order to do so, I needed to create a new class inheriting from `ContentRepositoryDescriptorBase`. From there, I created a custom UrlResolver class to render the links appropriately. Here is the full class below that adds the extra field I was after to the create link dialog window:

[ServiceConfiguration(typeof(IContentRepositoryDescriptor))]
public class ModalContentContentPickerDescriptor : ContentRepositoryDescriptorBase
{
    public IEnumerable<Type> ModelTypes
    {
        get
        {
            return typeof(IModalContentBlock).Assembly.GetTypes()
                .Where(x =>
                    typeof(IModalContentBlock).IsAssignableFrom(x)
                    && !x.IsInterface
                    && !x.IsAbstract).ToArray();
        }
    }

    public static string RepositoryKey => "modalContentRepo";

    public override string Key => RepositoryKey;

    public override string Name => "Modal Content";

    public override IEnumerable<Type> LinkableTypes => ModelTypes;

    public override IEnumerable<Type> ContainedTypes
    {
        get
        {
            var types = ModelTypes.ToList();

            types.AddRange(new[]
            {
                typeof(ContentFolder),
            });

            return types;
        }
    }

    public override IEnumerable<Type> CreatableTypes => ModelTypes;

    public override string SearchArea => "cms/blocks";

    public override IEnumerable<ContentReference> Roots =>
        new List<ContentReference>
        {
            ContentReference.SiteBlockFolder,
            ContentReference.GlobalBlockFolder,
        };

    public override IEnumerable<Type> MainNavigationTypes
    {
        get
        {
            return new[]
            {
                typeof(ContentFolder)
            };
        }
    }
}