Store complex object in TempData

Question

I\'ve been trying to pass data to an action after a redirect by using TempData like so:

if (!ModelState.IsValid)
{
    TempData[\"ErrorMessages\"] = ModelSta         


        

Answer 1

Using System.Text.Json in .Net core 3.1 & above

using System.Text.Json;

    public static class TempDataHelper
    {
        public static void Put(this ITempDataDictionary tempData, string key, T value) where T : class
        {
            tempData[key] = JsonSerializer.Serialize(value);
        }

        public static T Get(this ITempDataDictionary tempData, string key) where T : class
        {
            tempData.TryGetValue(key, out object o);
            return o == null ? null : JsonSerializer.Deserialize((string)o);
        }

        public static T Peek(this ITempDataDictionary tempData, string key) where T : class
        {
            object o = tempData.Peek(key);
            return o == null ? null : JsonSerializer.Deserialize((string)o);
        }
    }