After looking through the ASP.NET MVC 3 source code I have discovered that the reason for this is because the CreateMetadata
method is called prior to the OnMetadataCreated
method of any IMetadataAware
attributes that are applied to the model.
I have found an alternative solution that allows me to do what I wanted.
First of all I updated my AutocompleteAttribute
:
[AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
public class AutocompleteAttribute : Attribute, IMetadataAware
{
public const string Key = "autocomplete-url";
internal static IDictionary<string, string> Urls { get; private set; }
static AutocompleteAttribute()
{
Urls = new Dictionary<string, string>();
}
public void OnMetadataCreated(ModelMetadata metadata)
{
metadata.TemplateHint = "Autocomplete";
string url;
if (Urls.TryGetValue(metadata.PropertyName, out url))
{
metadata.AdditionalValues[Key] = url;
Urls.Remove(metadata.PropertyName);
}
}
}
and my Html helper method for setting the url in my views looks like this:
public static IHtmlString AutocompleteUrlFor<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression, string url)
{
if (string.IsNullOrEmpty(url))
throw new ArgumentException("url");
var property = ModelMetadata.FromLambdaExpression(expression, html.ViewData).PropertyName;
AutocompleteAttribute.Urls[property] = url;
return MvcHtmlString.Empty;
}
And then all I have to do in my editor template is this:
@{
object url;
ViewData.ModelMetadata.AdditionalValues.TryGetValue(AutocompleteAttribute.Key, out url);
var attributes = new RouteValueDictionary
{
{"class", "text-box single-line"},
{"autocomplete", "off"},
{ "data-autocomplete-url", url },
};
}
@Html.TextBox("", ViewContext.ViewData.TemplateInfo.FormattedModelValue, attributes)