MAKEMSI quickly and reliably creates MSI files in a non-programmatic way\Source CodeCommandsRegistryRead

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The "RegistryRead" Command

This command is used to "read" the value of a registry entry. The retrieved value is placed into a property specified by you.

This command takes these parameters:

• Property (required)
  This is the name of the property to be updated if the file is found (it must not contain lower case characters). This property is not created if the registry entry does not exist!

• Default (optional)
  Prior to searching for the registry entry the property is set to this value and no validation need take place. As the "Property" table is used the value doesn't support formatting.

  If not specified then the existance of the property will be validated (the install will fail if it does not exist).

  This value can be "" to indicate that no validation should take place (the property is not set to null).

• Message (optional)
  

  If you have not used the "Default" parameter and the MSI needs to display an error message it will use a default message unless you specify what it should say with this parameter. Note that the message can contain MSI formatting or "CRLF".

  The "Validate" parameter controls whether or not we will fail (displaying this message) if the file isn't found.

• Validate (optional)
  If you don't supply a default value then normally validation will take place to ensure the search succeeded, pass "N" in this parameter to prevent the validation.

  Due to Windows Installer restrictions you would also need to turn off validation if the existing registry values can contain empty strings (either that or prevent this if you control them by creating an empty "code").

• ValidateAfter (optional)
  The validation (if performed) is inserted into the "InstallUISequence" and "InstallExecuteSequence" tables. By default the check will be inserted after the standard "AppSearch" action, this parameter can be used to specify another action name.

• HKEY (required)
  This should be one of (see MSI doco for more info):
  • CLASSES_ROOT (or HKCR)
  • CURRENT_USER (or HKCU)
  • LOCAL_MACHINE (or HKLM)
  • USERS

• Key (required)
  This is the key of the registry value.

• Name (optional)
  This is the value key name of the registry value. This defaults to "", which shows up as "(Default)" in regedit.exe.

• 64Bit (optional)
  Pass "Y" to have the installer search the 64 bit portion of the registry, anything else means search the 32 bit portion instead.

  The default for this parameter can be set via the DEFAULT_REGISTRYREAD_64BIT macro. This is initially "N".

• Condition (optional)
  Not normally required but if specified is an extra condition which has to match for an error message to be displayed. This could be useful if you only wanted to validate during install etc.

• Signature (optional)
  A search "signature" is something that gets displayed to the user, it is an MSI "Identifier" and so can't contain spaces and most special characters.

  The default signature is the property name so if you make this meaningful then you probably don't need to use this parameter (except in the case where you might be populating the same property from two or more sources).

Format of the Results

The read is done via Windows Installer "RegLocator" and "AppSearch" table entries.

The documentation for these says that the returned result is prefixed with:

Obviously string values (which can bnever begin with "#") are the easiest to use, for other types (except for simple comparisons) you will probably need the help of a custom action to handle the value.

EXAMPLES

This shows how you can work out if you are on a workstation or server, the result is placed into the property "WINDOWS_PRODUCT_TYPE" (as there is no defined "default" value the install will abort if the value doesn't exist):

;--- Read the value ------------------------
#(
   <$RegistryRead
       Property="WINDOWS_PRODUCT_TYPE"
           HKEY="LOCAL_MACHINE"
            Key="SYSTEM\CurrentControlSet\Control\ProductOptions"
           Name="ProductType"
   >
#)

;--- Display the result in a message box ---
<$VbsCa Binary="DisplayProperty.vbs">
   <$VbsCaEntry "Install">
       PropertyBox("<$VbsCaEntryName>")
   <$/VbsCaEntry>

   <$VbsCaEntry "UnInstall">
       PropertyBox("<$VbsCaEntryName>")
   <$/VbsCaEntry>

   '=======================
   sub PropertyBox(When)
   '=======================
       ;--- Get the value of the MSI property ---------------
       dim PropertiesValue : PropertiesValue = VbsCaPropertyGet("WINDOWS_PRODUCT_TYPE", "", "")

       ;--- Display when we were invoked + property value ---
       CaMsgBox "I", "The " & When & "() routine was invoked." & vbCRLF & vbCRLF & "Property = " & PropertiesValue
   end sub
<$/VbsCa>
<$VbsCaSetup Binary="DisplayProperty.vbs" Entry="Install" Seq="AppSearch-" Type="immediate" SeqTable="InstallUISequence" CONDITION=^<$VBSCA_CONDITION_INSTALL_ONLY>^>

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