How to access session custom action data (properties) during install and uninstall in Wix?

Can you please tell me what is wrong with the following code? I am able to access the custom action data during install and I add their values to session custom action collection. However, during uninstall I the value pairs are not in the collection.

public class CustomActions
{
    //This action is only called during application install
    [CustomAction]
    public static ActionResult CreateToolbar(Session session)       
    {
        //This works fine the value is properly sent from wix script
        //The variable toolbarName has the expected value
        string toolbarName = session["VSTOCustomAction_ToolbarName"];

        //Save the value for uninstaller
        session.CustomActionData.Add("VSTOCustomAction_ToolbarName", toolbarName);
        ...
    }

    //This action is only called during application uninstall
    [CustomAction]
    public static ActionResult RemoveToolbar(Session session)
    {
        //Get the toolbar name and remove it
        //Why does the following call return null?
        string toolbarName = session.CustomActionData["VSTOCustomAction_ToolbarName"];          
        ...
    }
}

Below is the WIX part that calls the above custom action.

<!-- Include the VSTO Custom action  -->
<Binary Id="VSTOCustomAction" SourceFile="CustomAction.CA.dll"/>
<CustomAction Id="CreateToolbar" BinaryKey="VSTOCustomAction" DllEntry="CreateToolbar" Execute="immediate"/>
<CustomAction Id="RemoveToolbar" BinaryKey="VSTOCustomAction" DllEntry="RemoveToolbar" Execute="immediate"/>
...
<CustomAction Id="PropertyAssign_ToolbarName" Property="VSTOCustomAction_ToolbarName" Value="MyToolBarName"/>
...
<!-- Modify the install sequence to call our custom action -->
<InstallExecuteSequence>
  <Custom Action="PropertyAssign_ToolbarName" Before="CreateToolbar"><![CDATA[(&ToolbarComponent = 3) AND NOT (!ToolbarComponent = 3)]]></Custom>
  <Custom Action="CreateToolbar" After="InstallFinalize"><![CDATA[(&ToolbarComponent = 3) AND NOT (!ToolbarComponent = 3)]]></Custom>
开发者_开发百科  <Custom Action="RemoveToolbar" After="InstallFinalize"><![CDATA[(&ToolbarComponent = 2) AND NOT (!ToolbarComponent = 2)]]></Custom>
</InstallExecuteSequence>   

MSI doesn't persist properties after an install. Read the following for a good solution.

"The WiX toolset's "Remember Property" pattern." http://robmensching.com/blog/posts/2010/5/2/The-WiX-toolsets-Remember-Property-pattern

It seems that you are only creating the VSTOCustomAction_ToolbarName property when installing the ToolbarComponent, so when you try to uninstall, the VSTOCustomAction_ToolbarName property is never created, nor set.

One way to solve this problem could be saving the Toolbar Name on a Windows registry key instead of creating a property to contain this value, so you can read it while trying to uninstall your product.