gabrewer.com

Life is too important to be take seriously.

Passing values from your ASP.NET MVC Controller to Javascript

11 Dec 2012

Inspired by John Papa’s Single Page Application series on Pluralsight, in my latest project I am making heavy use of the JavaScript MVVM pattern.  Since my application isn't a true single page application I found myself in some cases needing use values from my Controller in my JavaScript methods.

After doing some research I came across this post from A. Friedman about Ngon a port he created of the Ruby Gon gem.  Ngon allows you to add a value to a ViewBag NGon property and then consume it in your JavaScript.

To use Ngon I can just add the NGonActionFilterAttribute to my RegisterGlobalFilters

public static void RegisterGlobalFilters(GlobalFilterCollection filters)
{
   filters.Add(new NGonActionFilterAttribute());
   filters.Add(new HandleErrorAttribute());
}

So in my controller action I just set the Ngon values.

if (User.Identity.IsAuthenticated)
{
   ViewBag.NGon.UserName = User.Identity.Name;
   ViewBag.NGon.CurrentUserId = WebSecurity.CurrentUserId;
}

In my _Layout.cshtml file I added a @using NGon and a @Html.IncludeNGon() to the <head> section.

@using NGon
<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8" />
        <title>@ViewBag.Title - My ASP.NET MVC Application</title>
        <link href="~/favicon.ico" rel="shortcut icon" type="image/x-icon" />
        <meta name="viewport" content="width=device-width" />
        @Html.IncludeNGon()
        @Styles.Render("~/Content/css")
        @Scripts.Render("~/bundles/modernizr")
    </head>
    <body>
...
 

And then I can just use the ngon object like this in my JavaScript

activate = function (callback) {

   config.currentUserId = ngon.CurrentUserId;
   config.currentUser = function () { return { id: function () { return ngon.CurrentUserId; } }; };

    messenger.publish.viewModelActivated({ canleaveCallback: canLeave });
    getActivityItems(callback);
},

Very elegant solution to the problem.  Ngon is now available as a Nuget package.

Comments