How can I inject ViewDataDictionary or ModelStateDictionary into TagHelper?

Question

In razor views I can access model state object:

@ViewData.ModelState

How can i inject and access ViewData or ModelState objects in razor TagHelper? I tried the following, however the ViewData and ModelState are always null:

public class ModelStateTagHelper : TagHelper
{
    public ViewDataDictionary ViewData { get; set; }
    public ModelStateDictionary ModelState { get; set; }

    public override void Process(TagHelperContext context, TagHelperOutput output)
    {
    }
}

Answer 1

You can inject IActionContextAccessor:

    public void ConfigureServices(IServiceCollection services)
    {
        //...
        services.AddSingleton<IActionContextAccessor, ActionContextAccessor>();
    }

    public class ModelStateTagHelper : TagHelper
    {
        public readonly IActionContextAccessor _accessor;

        public ModelStateTagHelper(IActionContextAccessor accessor)
        {
            _accessor = accessor;
        }
        public override void Process(TagHelperContext context, TagHelperOutput output)
        {
            var modelState = _accessor.ActionContext.ModelState;
        }
    }