ITempDataProvider in MVC 6 to use cookies for tempdata - asp.net

Question

I'm migrating a site over to use MVC 6. Currently I have tempdata store in cookies, but I can't find the set up of how to do this in the new MVC framework.

Answer 1

First, implement your ITempDataProvider. I did it this way, using JSON.Net.
public class CookieTempDataProvider : ITempDataProvider
{
readonly string CookieKey = "_tempdata";
public IDictionary<string,object> LoadTempData(HttpContext context)
{
var cookieValue = context.Request.Cookies[this.CookieKey];
if(string.IsNullOrWhiteSpace(cookieValue))
{
return new Dictionary<string, object>();
}
var decoded = Convert.FromBase64String(cookieValue);
var jsonAsString = Encoding.UTF8.GetString(decoded);
var dictionary = JsonConvert.DeserializeObject<IDictionary<string,object>>(jsonAsString, new JsonSerializerSettings { TypeNameHandling = TypeNameHandling.All, TypeNameAssemblyFormat = FormatterAssemblyStyle.Full });
// The cookie really should be deleted when the SaveTempData() method is called with an empty dictionary
// but that does not seem to be working for some reason. Added this delete for now (maybe this is a beta issue)
// TODO: Revisit at next release
context.Response.Cookies.Delete(this.CookieKey);
return dictionary;
}
public void SaveTempData(HttpContext context, IDictionary<string,object> values)
{
if (values == null || values.Count == 0)
{
context.Response.OnStarting(() => Task.Run(() =>
{
context.Response.Cookies.Delete(this.CookieKey);
}));
return;
}
var jsonAsString = JsonConvert.SerializeObject(values, new JsonSerializerSettings { TypeNameHandling = TypeNameHandling.All, TypeNameAssemblyFormat = FormatterAssemblyStyle.Full });
var bytes = Encoding.UTF8.GetBytes(jsonAsString);
var encoded = Convert.ToBase64String(bytes);
context.Response.Cookies.Append(this.CookieKey, encoded);
}
}
Next, in Startup.cs, where services are wired up, replace the default ITempDataProvider with your custom version, like so:
public void ConfigureServices(IServiceCollection services)
{
// Replace Temp Data Provider
var existing = services.FirstOrDefault(x => x.ServiceType == typeof(ITempDataProvider));
services.Remove(existing);
services.AddSingleton<ITempDataProvider, CookieTempDataProvider>();
}
EDIT
Since RC2 the original answer doesn't work any longer due to what seems like timing changes in the MVC request lifecycle...you'll receive an error about not being able to modify headers. I've updated the SaveTempData() method above to account for this.

Answer 2

I also had this need, so I've implemented a cookie-based TempData provider for ASP.NET Core MVC and published it on NuGet. It is available here.

Answer 3

If you think about TempData class for storing data for next request, there is some changes in MVC 6. You need to add additional package and configure it. Here are steps:
Remove "dnxcore50" from frameworks section in [project.json]. Session hasn't implementd yet in dnxcore50.
In the [project.json] add:
"Microsoft.AspNet.Session": "1.0.0-rc1-final"
Enable Caching and Session in class Startup.cs, method ConfigureServices, by adding next lines after services.AddMvc():
services.AddCaching();
services.AddSession();
Cinfigure it on class Startup.cs, method Configure, adding next line before app.UseMvc(...):
app.UseSession();
And that's it. But remember, you can store only primitive or serializable data types. If you need to store user defined data type, you need to serialized it. For that purpose we use "Newtonsoft.Json" lib. Here is example:
string json = JsonConvert.SerializeObject(myObject);
TempData["myKey"] = json;