Get WiX / MSI to install some registry always, preserve some pre-existing ones - wix

Question

I have a WiX installation that also needs to write some registry keys, and I was wondering if there's a way to tell WiX/MSI to
only create a key if it doesn't exist yet
always create/overwrite another key, even if it exists
I tried something like this:
<Wix xmlns="http://schemas.microsoft.com/wix/2006/wi">
<Product Id="*" Name="TestRegistry" Language="1033" Version="1.0.2"
Manufacturer="Myself" UpgradeCode="PUT-GUID-HERE">
<Package InstallerVersion="200" Compressed="yes"
InstallScope="perUser" InstallPrivileges="limited" />
<MajorUpgrade DowngradeErrorMessage="A newer version installed." />
<MediaTemplate EmbedCab="yes" />
<Feature Id="ProductFeature" Title="TestRegistry" Level="1">
<ComponentRef Id="ProductComponents" />
</Feature>
</Product>
<Fragment>
<Directory Id="TARGETDIR" Name="SourceDir">
<Directory Id="ProgramFilesFolder">
<Directory Id="dirManufacturer" Name="Manufacturer">
<Directory Id="INSTALLFOLDER" Name="TheProduct">
<Component Id="ProductComponents" Guid="*" DiskId="1">
<RegistryKey Root="HKCU" Key="Software\Manufacturer\TheProduct"
Action="createAndRemoveOnUninstall">
<RegistryValue Type="string" Name="Install Directory"
Value="[INSTALLFOLDER]" KeyPath="yes" />
<RegistryValue Type="string" Name="Product Version"
Value="[ProductVersion]" />
<RegistryValue Type="string" Name="Default Language" Value="en" />
<RegistryValue Type="string" Name="Web Site URL"
Value="https://product.manufacturer.info/" />
</RegistryKey>
</Component>
</Directory>
</Directory>
</Directory>
</Directory>
</Fragment>
</Wix>
and here, I'd like to always overwrite the Install Directory and Product Version keys with current values, but I would like to preserve other settings, like Default Language.
Is there any way to do this?
Right now, when I install 1.0.0 fresh on a new system, it creates the registry keys alright. When I uninstall it, they're gone - so far, so good.
But when I installed v1.0.1 and then - without uninstalling v1.0.1 - installed v1.0.2 on top of this, ALL the defined registry keys were updated and contained the default values defined in the WiX script - the changes I had made manually were wiped out.

Answer 1

You will need to break the registry values out to there own components and set the NeverOverwrite attribute on them
<Component Id="DefaultLangaugeComponent" Guid="*" NeverOverwrite="yes">
<RegistryKey Root="HKCU" Key="Software\Manufacturer\TheProduct"
Action="createAndRemoveOnUninstall">
<RegistryValue Type="string" Name="Default Language" Value="en" />
</RegistryKey>
</Component>