Attribute name change in array with mapper

I’m attaching a pipeline that I think demonstrates what you’re looking for:

DateLoop_2019_04_17.slp (5.1 KB)

I used a Sequence snap to generate a document for each day and then use some of the Date arithmetic methods to build the desired values in a Mapper.

To compute the difference between the two dates, I used this expression library:

https://raw.githubusercontent.com/SnapLogic/contrib-elib/master/datetime.expr

If you use the library, you probably should download it from that link and place it in the project with the pipeline.