WIX get runtime variable from msi to transform another

Question

I'm implementing exe installer with two msi. During installation of first one user have to select value from ComboBox and I want to use selected value as parameter to run transformation on second msi. I'm using dotNetInstaller bootstrapper (with no UI) and have to configure msiexec parameters as TRANSFORMS="[variable from first msi]"

I tried to use system variable but it wan't work. How can I get ui-property value to transform second msi?

Answer 1

Based on your current design, I'd say the simplest way is for the first MSI to store the property in a registry value and then have the second MSI ( or a transform of the second MSI ) read the registry value into a property.

Normally I'd have your boostrapper/chainer (EXE) do the UI and then pass the values to the child packages.