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February 25, 2010|Donn Felker

ASP.NET MVC TempData Extension Methods

This is an sister class to some Session classes I wrote awhile back (which I never posted). I originally wrote these extension methods for the code camp eval system for Twin Cities Code Camp last year. But I needed it today at my client so I figured I’d post it here for future reference … and so you could use it.

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public static class TempDataExtensions
{
    public static void Put<T>(this TempDataDictionary tempData, T value) where T : class
    {
        tempData[typeof(T).FullName] = value;
    }
 
    public static void Put<T>(this TempDataDictionary tempData, string key, T value) where T : class
    {
        tempData[typeof(T).FullName + key] = value;
    }
 
    public static T Get<T>(this TempDataDictionary tempData) where T : class
    {
        object o;
        tempData.TryGetValue(typeof(T).FullName, out o);
        return o == null ? null : (T)o;
    }
 
    public static T Get<T>(this TempDataDictionary tempData, string key) where T : class
    {
        object o;
        tempData.TryGetValue(typeof(T).FullName + key, out o);
        return o == null ? null : (T)o;
    }
}

The code above allows you to put values into TempData in a strongly typed fashion. You can then get the values back out (safely) without worrying about an exception being thrown (temp data will throw if the key is not found).

Usage:

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var customer = new Customer();
 
TempData.Put(customer); // Strongly typed without key
 
TempData.Put("key1", customer); // Strongly typed with extra key
 
var tempDataCustomer = TempData.Get<Customer>(); // Get customer without key
 
var tempDataCustomerWithKey = TempData.Get<Customer>("key1"); // Get customer with key