Troubleshooting ASP.NET Core Object Transfer Issues with TempData: A Guide to Resolve HTTP Error 500

Encountering an issue when trying to transfer an object between methods using TempData in ASP.NET Core, and it’s resulting in an HTTP ERROR 500. The problem might be related to serializing and deserializing complex objects when using TempData.

Here’s a solution that you can try:

1. Use JSON Serialization for Object

When storing complex objects in TempData, it’s a good practice to serialize them to a JSON string before storing and deserialize them when retrieving. This ensures that the object retains its structure.

Modify your IP method:

public IActionResult IP(string ipDec)
{
    IPInfos ipInfos = InternetProtocolService.IPCalculate(ipDec);

    // Serialize the object to JSON before storing in TempData
    TempData["IP"] = Newtonsoft.Json.JsonConvert.SerializeObject(ipInfos);

    return View(ipInfos);
}

And modify your IPSubnetsSM method:

public IActionResult IPSubnetsSM(int subnetCount)
{
    // Deserialize the object when retrieving from TempData
    string ipInfosJson = (string)TempData["IP"];
    IPInfos ipInfos = Newtonsoft.Json.JsonConvert.DeserializeObject<IPInfos>(ipInfosJson);

    ipInfos.SubnetCount = subnetCount;
    return View(ipInfos);
}

2. Check TempData for Null

Ensure that the TempData key “IP” exists before attempting to retrieve it in the IPSubnetsSM method:

public IActionResult IPSubnetsSM(int subnetCount)
{
    if (TempData.ContainsKey("IP"))
    {
        string ipInfosJson = (string)TempData["IP"];
        IPInfos ipInfos = Newtonsoft.Json.JsonConvert.DeserializeObject<IPInfos>(ipInfosJson);

        ipInfos.SubnetCount = subnetCount;
        return View(ipInfos);
    }
    else
    {
        // Handle the case where TempData["IP"] is not found
        // Redirect or return an error view
        return RedirectToAction("Error");
    }
}

By making these adjustments, you ensure that the complex object is properly serialized and deserialized when stored and retrieved from TempData. Additionally, checking for TempData existence helps prevent null reference exceptions.

Give these changes a try, and it should resolve the HTTP ERROR 500 you’re encountering. If the issue persists, you might want to check the application logs for more detailed error information.