title: Get property name in Tag Helper
body: <p>ASP.NET Core introduced custom tag helpers which can be used in views like this:</p>
  
  <pre><code>&lt;country-select value="CountryCode"  /&gt;
  </code></pre>
  
  <p>However, I don't understand how can I get model property name in my classes:</p>
  
  <pre><code>public class CountrySelectTagHelper : TagHelper
  {
      [HtmlAttributeName("value")]
      public string Value { get; set; }
  
      public override void Process(TagHelperContext context, TagHelperOutput output)
      {
         ...
         // Should return property name, which is "CountryCode" in the above example
         var propertyName = ???();  
         base.Process(context, output);
      }
  }
  </code></pre>
  
  <p>In the previous version I was able to do this by using <code>ModelMetadata</code>:</p>
  
  <pre><code>var metadata = ModelMetadata.FromLambdaExpression(expression, html.ViewData);
  var property = metadata.PropertyName; // return "CountryCode"
  </code></pre>
  
  <p>How can I do the same in the new <code>ASP.NET</code> tag helpers?</p>