I am using ASP.NET MVC 2 Preview 2 and have written a custom HtmlHelper extension method to create a label using an expression. The TModel is from a simple class with properties and the properties may have attributes to define validation requirements. I am trying to find out if a certain attribute exists on the property the expression represents in my label method.
The code for the class and label is:
public class MyViewModel
{
[Required]
public string MyProperty { get; set; }
}
public static MvcHtmlString Label<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, string label)
{
return MvcHtmlString.Create(string.Concat("<label for="", expression.GetInputName(), "">", label, "</label>"));
}
public static string GetInputName<TModel, TProperty>(this Expression<Func<TModel, TProperty>> expression)
{
return expression.Body.ToString().Substring(expression.Parameters[0].Name.Length + 1);
}
Then I would call the label like this:
Html.Label(x => x.MyProperty, "My Label")
Is there a way to find out if the property in the expression value passed to the Label method has the Required attribute?
I figured out that doing the following does get me the attribute if it exists, but I am hopeful there is a cleaner way to accomplish this.
public static MvcHtmlString Label<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, string label)
{
System.Attribute.GetCustomAttribute(Expression.Property(Expression.Parameter(expression.Parameters[0].Type, expression.GetInputName()), expression.GetInputName()).Member, typeof(RequiredAttribute))
return MvcHtmlString.Create(string.Concat("<label for="", expression.GetInputName(), "">", label, "</label>"));
}
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