How to conditionally exclude features from “FeaturesDlg” in WiX 3.0 from a managed Custom Action (DTF)

Question

I am trying to put together an installer using WiX 3.0 and I'm unsure about one thing. I would like to use the FeaturesDlg dialog to allow the users to select features to install, but I need to be able to conditionally exclude some features from the list based on some input previously received, preferably from a managed Custom Action.

I see that if I set the Display attribute of a Feature to hidden in the .wxs file that it does what I want, but I can't figure out a way to change that attribute at runtime.

Any pointers would be great.

Edit:

I tried using SQL to update the session Database, but while I can actually delete the feature using DELETE FROM Feature WHERE Feature = 'featureId', if I try to use UPDATE Feature SET Display=0 WHERE Feature='featureId', I get an UPDATE FAILED error. If I try to set the Display value to anything other than what it's already set at I get that error.

Deleting the feature is ALMOST good enough, but I would need to be able to go back and re-add the feature if the user goes Back and changes some input data.

Answer 1

Well I think I found a solution by accident. After a bunch of experimenting I ran across an error message from MSI that kinda described some columns for the Feature table in the current session, and there was a column "RuntimeLevel" that is not described in any docs that I could find. So I tried this:

session.Database.Execute("UPDATE Feature SET RuntimeLevel=0 WHERE Feature='MyFeature'");

And it worked; the feature was no longer listed in the SelectionTree. Then I ran the same query again with RuntimeLevel=1, and it was listed again.

Since I'm not sure if there are any strange implications for this solution I am going to leave the question open for a while longer, just in case somebody else has a "better" solution.

Answer 2

I needed to do the same and found this...

Create a property.. which will be set by the CA or whatever...

  <Property Id='INSTALL_FEATURE_2'>YES</Property>

Then use the property inside your feature...

  <Feature Id='ASecondFeature' Title='Feature 2' Level='1'>
    <Condition Level='0'>INSTALL_FEATURE_2 = "NO"</Condition>
    <ComponentGroupRef Id='secondComponent'/>  
  </Feature>

note the the condition dosent directly set whether the parent is installed as with files and the like, it sets the Level attribute on the parent feature. Setting it to 0 makes it hidden... voilà!

Answer 3

The example above is the correct way to conditionally offer a feature (except that it's recommended that the condition should be in a CDATA section), however since you said you wanted to decide this in your custom action...

Given a feature like this:

<Feature Id="MyFeature" Title="My Title" Level="1" >
  <Condition Level="0"><![CDATA[NOT(INSTALLMYFEATURE~="TRUE")]]></Condition>
  <ComponentGroupRef Id="MyFeatureComponentGroup" />
</Feature>

In your managed custom action you receive a "Session" object. If you want to make the feature available for the user, set the INSTALLMYFEATURE property to "True", otherwise set it to "False".

session["INSTALLMYFEATURE"] = "True";

or

session["INSTALLMYFEATURE"] = "False";