Conditional Installation of .NETFramework 4.8

[sansa20]

I have a WiX installer and I have created a bootstrapper project for the same in order to install version 4.8 of .NETFramework as my pre requisites. However, I would like pre-requisites to only get installed if it is not already there on the system.
Additionally, I have a requirement to install the pre-requisite directly from my computer (I have a pre-requisites folder in my file explorer), and not from the internet. Following is the code I have so far under my bundle.wxs file. Any help would be much appreciated.

<Fragment>
        <PackageGroup Id="DotNet">
            <ExePackage SourceFile="..\..\..\External\Prerequisites\.NET Framework\ndp48-web.exe"
                        DetectCondition="ExeDetectedVariable"
                        InstallCommand="/q /ACTION=Install"
                        RepairCommand="/q ACTION=Repair /hideconsole"
                        UninstallCommand="/q ACTION=Uninstall /hideconsole"/>
        </PackageGroup>
    </Fragment> 

[robmen]

Use a correct DetectCondition and it will behave exactly as you desire.

[sansa20]

I understand that if the detect condition is evaluated as false, only then the package will be installed on the machine. However, I am unsure what value is to be passed inside- is there any official documentation I could use to understand the same?

[robmen]

Yes, there is.