asp.net mvc 3 - Share enums between C# and Javascript in MVC Razor

Question

I have seen this useful answer to a question for adding constants into a javascript file so it can be used with razor views: Share constants between C# and Javascript in MVC Razor

I'd like to be able to do the same except define enums, but I'm not sure how to convert the C# Enum into a constant in javascript.

Off GetType(), there doesn't seem to be a way of actually getting at the constant value.

Answer 1

I took a mixture from several people's answers and wrote this HtmlHelper extension method:

public static HtmlString GetEnums<T>(this HtmlHelper helper) where T : struct
{
    System.Text.StringBuilder sb = new System.Text.StringBuilder();
    sb.AppendLine("<script type="text/javascript">");
    sb.AppendLine("if(!window.Enum) Enum = {};");
    var enumeration = Activator.CreateInstance(typeof(T));
    var enums = typeof(T).GetFields().ToDictionary(x => x.Name, x => x.GetValue(enumeration));
    sb.AppendLine("Enum." + typeof(T).Name + " = " + System.Web.Helpers.Json.Encode(enums) + " ;");
    sb.AppendLine("</script>");
    return new HtmlString(sb.ToString());
}

You can then call the method using Razor syntax like this: @(Html.GetEnums<Common.Enums.DecisionStatusEnum>())

It will then spit out javascript like this:

<script type="text/javascript">
    if(!window.Enum) Enum = {};
    Enum.WorkflowStatus = {"value__":0,"DataEntry":1,"SystemDecisionMade":2,"FinalDecisionMade":3,"ContractCreated":4,"Complete":5} ;
</script>

You can then use this in javascript like such:

if(value == Enum.DecisionStatusEnum.Complete)

Because of the check for property at the top (if(!window.Enum)), this allows you to call it for multiple enums and it won't overwrite the global Enum variable, just appends to it.