Initializer syntax: new ViewDataDictionary { { "Name", "Value" } }

Question

I was searching for a way to pass ViewDataDictionary to a partial view in ASP.NET MVC that I came to this syntax:

new ViewDataDictionary { { "Name", "Value" } }

I'm a bit confused about the initializer syntax here. can anyone explain it to me?

Answer 1

I solved this using an extension method:

/// <summary>
/// Use this extension method to create a dictionary or objects
///     keyed by their property name from a given container object
/// </summary>
/// <param name="o">Anonymous name value pair object</param>
/// <returns></returns>
public static Dictionary<string, object> ToDictionary(this object o)
{
    var dictionary = new Dictionary<string, object>();

    foreach (var propertyInfo in o.GetType().GetProperties())
    {
        if (propertyInfo.GetIndexParameters().Length == 0)
        {
            dictionary.Add(propertyInfo.Name, propertyInfo.GetValue(o, null));
        }
    }

    return dictionary;
}

And an Html Helper extension:

/// <summary>
/// When viewData is null, we just return null.  Otherwise, we
///     convert the viewData collection to a ViewDataDictionary
/// </summary>
/// <param name="htmlHelper">HtmlHelper provided by view</param>
/// <param name="viewData">Anonymous view data object</param>
/// <returns></returns>
public static ViewDataDictionary vd(this HtmlHelper htmlHelper, object viewData)
{
    if (viewData == null) return null;

    IDictionary<string, object> dict = viewData.ToDictionary();

    //We build the ViewDataDictionary from scratch, because the
    //  object parameter constructor for ViewDataDictionary doesn't
    //  seem to work...
    ViewDataDictionary vd = new ViewDataDictionary();
    foreach (var item in dict)
    {
        vd[item.Key] = item.Value;
    }

    return vd;
}

Use from a razor file as:

@Html.Partial("~/Some/Path.cshtml", Model, Html.vd(new { SomeKey = SomeObj }))