WiX how to import/export data into C# Custom Action?

Question

I need to:

1. get data from users (from a UI), and put that data into Properties
2. import the Properties into some C# code using a Custom Action
3. do some stuff to the Properties (encrypt the values),
4. export the values back to WiX, where I will
5. create a registry key and put the encrypted values into them

I can accomplish everything on that list except for #4. That is, I can't seem to import and export values into the C# code. I think the problem is in the timing.

Here's an example of a Custom Action that is used to import some properties into some C# code:

  <Property Id="VALUE" Value="value"/>
  <SetProperty Id="CustomAction_PassProperty"
               Value="VALUE=[VALUE]"
               Sequence="execute"
               Before="CustomAction_PassProperty"/> 

  <Binary Id="Binary_PassProps"
          SourceFile="$(var.CreateRegistryKey.TargetDir)CreateRegistryKey.CA.dll"/>

  <!-- Note that 'Impersonate="no"' elevates the privilege of the C# code, needed to create keys -->
  <CustomAction Id="CustomAction_PassProperty"
                BinaryKey="Binary_PassProps"
                DllEntry="CreateKeys"
                Execute="deferred"
                Impersonate="no"
                Return="check" 
                HideTarget="yes"/>

  <InstallExecuteSequence>
      <Custom Action="CustomAction_PassProperty"
              After="InstallInitialize"/>
  </InstallExecuteSequence>

Notice that the action is done after InstallInitialize.

Next, how to take the imported properties and convert them into variables in the C# code:

    [CustomAction]
    public static ActionResult CreateKeys(Session session)
    {
        string value = session.CustomActionData["VALUE"];
        return ActionResult.Success;
    }

Next, here's an example of how to export variables in C# code back into WiX, as properties:

<Binary Id="Binary_CustomActionTemplate" 
        SourceFile="$(var.CustomAction.TargetDir)CustomAction.CA.dll"/>

<CustomAction Id="CustomAction_CustomActionTemplate" 
              BinaryKey="Binary_CustomActionTemplate" 
              DllEntry="CustomActionTemplate" 
              Execute="immediate" 
              Return="check"/>

<InstallUISequence>
    <Custom Action="CustomAction_CustomActionTemplate" After="LaunchConditions"/>
</InstallUISequence>

And this time the action is done after LaunchConditions.

Finally, how to create a Property, give it a value, and send it back to WiX in C#:

    [CustomAction]
    public static ActionResult CreateKeys(Session session)
    {
        session["VALUE"] = "Hello, world.";
        return ActionResult.Success;
    }

I think the problem lies in when -- that is, when during the installation sequence -- that I do both things (import and export), but I'm not sure. That is, I need to import the data into the C# code, do stuff in the C# code, then export data from C# code. But how?!? (waves hands dramatically at sky)

To sum up: how to import and export data into C# Custom Action in WiX (using the same C# code)?

Answer 1

AFAIK you cannot alter property values once in the execute sequence. Someone can correct me if I'm wrong and that would be an alternative answer to your question.

You should be able to encrypt the properties in the UI phase of the install. In your immediate custom action you can access the msi properties with session["PROPERTYNAME"] as opposed to session.CustomActionData["PROPERTYNAME"]. You can also set the properties: session["PROPERTYNAME"] = "new value string";.

Then on your Next/Install control on the page where the information is added you can put

<Control Id="Install" ...>
    <Publish Event="DoAction" Value="EncodeAndSetValuesAction">1</Publish>
    ....
</Control>

If they are marked Secure='yes' and public (all caps name) then they should be usable in the execute phase of your installation with the encoded values.

Do note that if you launch your custom action with a DoAction control event (clicking next on the page where the user enters the values) you won't be able to get logging information in the msi log. See here for more info.

Small edit: I was writing this answer when you edited the question which shows you already know how to get the properties and set them in an immediate action.

Alternatively, you may be able to just schedule an immediate custom action to encrypt and set the values in the InstallExecuteSequence before InstallInitialize (or before WriteRegistryValues or anywhere?) and it will set the properties before the elevated Server portion of the install starts. I think the InstallExecuteSequence happens in two parts. One where it does a pass figuring out values and which files to install making an install script for the elevated Server portion of the install where it actually copies the files around and writes registry keys ect. This part is still the client context where you can run immediate custom actions and read/set properties. Secondly it will start the Server portion of the install with set in stone properties and follow the execution script that was just created.

---

I decided to put a short simplified explanation about the differences between immediate and deferred custom actions here as well.

There are basically two main differences between deferred and immediate custom action. Immediate custom actions can access the msi DB directly to read and/or modify properties but can't do anything that requires elevation unless the installer was run "as administrator" since it runs in the user's context.

Deferred actions can only run in the execute sequence and can only read property values set explicitly through CustomActionData with the same name as the action but they always have elevated privileges.