To fix the case not covered in the previous example, we need to add two custom actions (per property) to save the property value if it is set from the command line. Both actions should be immediate actions:

• one should be scheduled before the AppSearch stage and save property passed through the command line into a temporary property
• the other should be scheduled after AppSearch and restore property value from a temporary property (only if the property was passed on the command line)

    <CustomAction Id='SaveCmdLineValue_MY_PROPERTY' Property='CMDLINE_MY_PROPERTY' Value='[MY_PROPERTY]' Execute='firstSequence' />
    <CustomAction Id='SetFromCmdLineValue_MY_PROPERTY' Property='MY_PROPERTY' Value='[CMDLINE_MY_PROPERTY]' Execute='firstSequence' />
    <InstallUISequence>
      <Custom Action='SaveCmdLineValue_MY_PROPERTY' Before='AppSearch' />
      <Custom Action='SetFromCmdLineValue_MY_PROPERTY' After='AppSearch'>
        <![CDATA[CMDLINE_MY_PROPERTY AND (CMDLINE_MY_PROPERTY <> "default value")]]>
      </Custom>
    </InstallUISequence>
    <InstallExecuteSequence>
      <Custom Action='SaveCmdLineValue_MY_PROPERTY' Before='AppSearch' />
      <Custom Action='SetFromCmdLineValue_MY_PROPERTY' After='AppSearch'>
        <![CDATA[CMDLINE_MY_PROPERTY AND (CMDLINE_MY_PROPERTY <> "default value")]]>
      </Custom>
    </InstallExecuteSequence>

NOTE: If the property does not have a default value, the AND (CMDLINE_MY_PROPERTY <> "default value") part is not needed.

If we now repeat Executing install/upgrade/repair/uninstall with previously defined custom actions and during step 3 (upgrade) pass MY_PROPERTY=my_value_2 to the installer, we should get the following result:

18:55:01.312 - C:\Example_06\ - 1.0.0.0 - my_value - FirstInstall
18:55:06.796 - C:\Example_06\ - 1.0.0.0 - my_value - Maintenance
18:55:27.954 - C:\Example_06\ - 2.0.0.0 - my_value_2 - Upgrading
18:55:32.305 - C:\Example_06\ - 2.0.0.0 - my_value_2 - Maintenance
18:55:44.354 - C:\Example_06\ - 2.0.0.0 - my_value_2 - Uninstalling

As seen from the result, property value is successfully changed during the upgrade.
NOTE: Properties cannot be changed during repair - according to this, the /f option "ignores any property values entered on the command line".

• Real-World Example: WiX/MSI Application Installer
  Sample installer that also implements Remember Property pattern