How to write setup build date to a property - wix

Question

Update 2: The feature request has been declined, simply because WiX cannot support these "fake" variables cmd.exe offers. So the accepted answer below remains the best solution.
Update: I have issued a feature request for adding preprocessor dynamic environment variable support. As soon as the devs respond, I'll update this thread.
Original Question:
I want to write the date when the setup has been built to a property.
<Property Name="BuildDate" Value="$(env.Date)" />
or
<Property Name="BuildDate" Value="$(sys.Date)" />
throws CNDL0150: "Undefined preprocessor variable" while
<Property Name="BuildDate" Value="[Date]" />
will of course write the string "[Date]" to the MSI property.
How can I achieve this?
Edit: I've tried "Date" in all cases, same result. Also, adding a new environment variable called "BuildDate" and setting it to "%DATE%" removes the compilation error, but the value written to the MSI doesn't resolve to the actual date, instead it yields the string "%DATE%".

Answer 1

You can add a property in you wix project (.wixproj) in your first property group, for example (you can format the date and/or time to your liking):
<Date>$([System.DateTime]::Now.ToString("yyyyMMddhhmm"))</Date>
Then in your configurations property groups add this property in <DefineConstants>, if you have more constants then separate them with semicolon ;:
<DefineConstants>Date=$(Date)</DefineConstants>
Lastly add the MSI Property:
<Property Id="BuildDate" Value="$(var.Date)" />

Answer 2

Try to use all uppercase DATE, like this:
<Property Name="BuildDate" Value="$(env.DATE)" />
UPDATE: My initial guess was not correct - environment variables are case-insensitive when referenced this way.
It seems like it depends on the type of the environment variable. There are standard environment variables, like %TEMP%, %windir%, etc. Those are "static", meaning the value is not calculated each time you reference it.
There are dynamic environment variables, which are calculated each time they are referenced. These include %DATE%, %TIME%, etc. It seems that WiX preprocessor can't work with dynamic variables. You can verify this: put $(env.windir) and it will work, put $(env.time) - and it won't. More info about environment variables can be found here.
I have not verified whether there's a wish in WiX bug database to support this. Feel free to do it yourself.
So, back to your question. You can work around this limitation in the following way:
Create preprocessor extension
Reference the value from that extension instead of addressing environment variable direcly
The sample how to create preprocessor extension can be found here.
Here's a sample of the code which does the job:
public class DateExtension : PreprocessorExtension
{
public override string[] Prefixes
{
get
{
return new[] { "date" };
}
}
public override string GetVariableValue(string prefix, string name)
{
string result = null;
switch (prefix)
{
case "date":
switch (name)
{
case "Now":
result = DateTime.Now.ToShortDateString();
break;
}
break;
}
return result;
}
}
And in your WiX code you can use it in the following way:
<Property Id="BuildDate" Value="$(date.Now)" />
Don't forget to:
pass preprocessor extension DLL to the WiX setup project (-ext path/to/PreprocessorExtension.dll)
add [assembly: AssemblyDefaultWixExtension(typeof(PreprocessorWixExtension))] to the preprocessor extension project
Here is the result I observe in the MSI package:

Answer 3

To set property value from another property use the following syntax:
<SetProperty Id="BuildDate" Value="[Date]" After="InstallInitialize" />