You're not following because you don't want to follow.
I think that anyone with a "commit bit" on this project that tolerates that sentence is a much better human being than I ever will be.
I may be the dumbest person on this list by many measures - but isn't there standard options that are supposed to be the first line of defense here? Why do I need a function to ensure I don't remove data by passing a NULL value to an update?
Why would any of these standard statements not solve this issue?
update users set info=jsonb_set(info, '{bar}', info->'foo')
where info->'foo' is not null
update users set info=jsonb_set(info, '{bar}', info->'foo')
where jsonb_set(info, '{bar}', info->'foo') is not null
update users set info=coalesce(jsonb_set(info, '{bar}', info->'foo'), info)
I can totally respect the person that slams into this wall the first time and is REALLY upset about it - but by their own admission this has occurred multiple times in this project and they continue to not take standard precautions.
Again, I applaud the patience of many people on this list. You deserve much more respect than you are being shown here right now.
John W Higgins