How do I instruct my Savable Data Page to use POST vs. PUT/PATCH for updates to REST APIs?
Conditional logic in the Save Plan can test a property (which property is up to you & your design) staged on the Data Page to determine whether it should do a Create or Update operation, and use the appropriate save path. This allows the one Savable Data Page to have:
One Save option that uses the POST operation (for Create), and
One Save option that uses the PUT or PATCH operation (for Update).
This should cover most use cases that prevent you from having to step into an Activity to handle these distinctions. Consider the Activity as a last resort in this scenario, but feel empowered to use an Activity if needed. If the version of Pega you are using does not provide 'Connector' as one of your Save types, then you will need an Activity.