Alf Nilsson talks

I’ve seen more and more examples on how to NOT use properties on your Content Types – setting visit/Request specific information to them.

My example below is a very harmless, but I’ve seen examples where the price for an e-com site is set like this!

How do you mean?

The example would be to display the visitor’s IP, which is common to be different for each request.

First of all we have a Block Type:

[ContentType(GUID = "5597f215-f5cc-4fd0-bcff-eb06a44fc343")
public class MyPage : PageData
{
    public string MyProperty { get; set; }
}

And the controller set’s the value:

public class MyPageController : PageControllerBase<MyPage>
{
    public ActionResult Index(MyPage currentPage)
    {
        currentPage.MyProperty = Request.UserHostAddress;
        return View(currentPage);
    }
}

And a view displays it:

@model MyPage
Name: @Html.PropertyFor(m => m.Name)
IP: @Model.MyProperty

But what’s the problem?

The problem is that each instance of MyPage is cached and could basically be referred to as “static” – when a value is set to MyProperty, the value is set for all visitors.

For example when visitor A visits from IP address “192.168.0.10”, MyProperty is set with the IP. When visitor B visits from “192.168.0.11”, MyProperty will still have the value from visitor A until the controller sets the IP from visitor B.

Or even worse: When the the visitor A comes to the view and MyProperty is rendered there is a chance that visitor B comes to the controller and sets a new value to MyProperty – so that the view will render the IP from visitor B.

I’m sorry for the crappy GIF, but hope you get the point ;)

So what should I do?

Make sure that you have a specific class that contains your information and create a new instance of this class for each Request. For my example I would have a viewmodel instead. In Episerver projects the ViewModel could also contain the Content itself:

[ContentType(GUID = "5597f215-f5cc-4fd0-bcff-eb06a44fc343")
public class MyPage : PageData
{
}

public class MyPageViewModel
{
    public string MyProperty { get; set; }
    public MyPage CurrentPage { get; set; }
}

With the Controller

public class MyPageController : PageControllerBase<MyPage>
{
    public ActionResult Index(MyPage currentPage)
    {
        var viewModel = new MyPageViewModel
        {
             MyProperty = Request.UserHostAddress,
             CurrentPage = currentPage
        };
        return View(viewModel);
    }
}

And with the View

@model MyPageViewModel
Name: @Html.PropertyFor(m => m.CurrentPage.Name)
IP: @Model.MyProperty

Again this a simple example, but say you’re having an e-com solution and want to display the price. You don’t want to display other visitor’s prices don’t you? ;)