How to pass msiexec properties to a WiX C# custom action


I have an MSI file being created with Wxs 3.0. My MSI references a C# custom action, written using the new C# Custom Action project.

I want to pass an argument to msiexec that gets routed to my custom action – for example:

msiexec /i MyApp.msi ENVIRONMENT=TEST#

In my .wxs file, I refer to my custom action like this:

<Property Id="ENVIRONMENT"/>
<Binary Id="WixCustomAction.dll"  SourceFile="$(var.WixCustomAction.Path)" />
<CustomAction Id="WixCustomAction" BinaryKey="WixCustomAction.dll"    DllEntry="ConfigureSettings"/>
   <Custom Action="WixCustomAction" After="InstallFiles"></Custom>

My C# custom action is set up like this:

public static ActionResult ConfigureSettings(Session session)


I was expecting to be able to access the property like this:

string environmentName = session.Property["ENVIRONMENT"];

but this doesn't seem to work.

How do I access the property I passed to msiexec in my custom action?

Best Solution

If instead of

<CustomAction Id="SetCustomActionDataValue"

you write this:

<CustomAction Id="SetCustomActionDataValue"
              Value="Environment=[ENVIRONMENT];G=G2;ConfigFile=[CONFIGFILE];TargetDir=[TARGETDIR]ITP_v$(var.VERSION_MAJOR)" />

then you will be able to reference your variables like this:

string env=session.CustomActionData["Environment"];
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