Mapping two-column result set to Map

[acanthite1855]

It would be nice to have a simple built-in way top map two-column result set to a Map. Just like mapping single-column results to List or Set.

Currently, my options either to create a DTO and then manually do result.stream().collect(toMap(Dto::getId, Dto::getCount)) or use @MapKey("id") and Map<Long, Dto> or use ResultHandler, which is basically the same as streams but ugly, though it does not allocate unnecessary instances of Dto class.

At least that's the options I've found on google so far. I mean, it is quite a common issue.

Are there any limitations that make it impossible to implement such mapping as a built-in feature?

[harawata]

Thank you for sharing the idea, @lowercase1024 !

There are many particular usages that are considered to be common and this may be one of them.
Like other similar requests, however, to achieve this, we may have to create a logic specific to this mapping pattern, so I would say 'no' at least for now.
Using ResultHandler probably is the best solution at this point.

If someone has a clean implementation idea, feel free to send us a PR and we will review it.