How to populate javascript variable with JSON from ViewBag?

Question

I have this Index action:

public ActionResult Index()
{  
    var repo = (YammerClient) TempData["Repo"];
    var msgCol = repo.GetMessages(); 

    ViewBag.User = repo.GetUserInfo();
    return View(msgCol.messages);
}

GetMessages returns a list of POCO messages and GetUserInfo returns a POCO with the info of the user (id, name, etc).

I want to fill a javascript variable with the JSON representation of the user info.

So I would want to do something like this in the view:

...
<script>
    var userInfo = "@ViewBag.User.ToJson()"
</script>
...

I know that doesn't work, but is there a way to do that? I want to avoid having to do an ajax request once the page is loaded just to get the user info.

Answer 1

In View you can do something like this

@{
        var jss = new System.Web.Script.Serialization.JavaScriptSerializer();
        var userInfoJson = jss.Serialize(ViewBag.User);
}

in javascript you can use it as

<script>


    //use Json.parse to convert string to Json
    var userInfo = JSON.parse('@Html.Raw(userInfoJson)');
</script>

Answer 2

Was using this solution for simple objects. But I had some problems getting an array to js objects so I'll just leave what I did here.

C#

@{
  using Newtonsoft.Json;
  ViewBag.AvailableToday = JsonConvert.SerializeObject(list);
}

js

var availableToday = JSON.parse('@Html.Raw(ViewBag.AvailableToday)');

Answer 3

Client-Side Code:

This is an ajax call to a .Net MVC Controller:

var clientStuff;

$.ajax({
    type: 'GET',
    url: '@Url.Action("GetStuff", "ControllerName")',
    data: {},
    dataType: "json",
    cache: false,
    async: false,
    success: function (data) {
        clientStuff = data;
    },
    error: function(errorMsg) {
        alert(errorMsg);
    }
});

Server-Side Code:

CONTROLLER:

    public JsonResult GetStuff()
    {
        return Json(_manager.GetStuff(), JsonRequestBehavior.AllowGet);
    }

MANAGER:

    public IEnumerable<StuffViewModel> GetStuff()
    {
        return _unitofWork.GetStuff();
    }

UNIT OF WORK:

    public IEnumerable<StuffViewModel> GetStuff()
    {
        var ds = context.Database.SqlQuery<StuffViewModel>("[dbo].[GetStuff]");
        return ds;
    }

Unit of Work can be a query to a sproc (as I have done), a repository context, linq, etc. I'm just calling a sproc here for simplicity, although it could be argued that the simplicity lies with Entity Framework and Linq.

Answer 4

You can change this line :

ViewBag.User = repo.GetUserInfo();

To

ViewBag.User = new HtmlString(repo.GetUserInfo());

You should add using Microsoft.AspNetCore.Html; or using System.Web; if HtmlString is not accessible.