JOOQ - map a single record using RecordMapper

Question

I am not able to use a RecordMapper mapper to map a single record retrieved via fetchOne/fetchAny.

If I use for example (like in the manual)

List<Something> list =  create.selectFrom(TABLE).fetch().map(mapper);

it works,

but if i use the same mapper for:

Something pojo = create.selectFrom(TABLE).fetchOne().map(mapper);

it doesn't compile.

Thanks for the help

Answer 1

This probably has to do with generics. While Result.map() takes a RecordMapper<? super R,E> RecordMapper<? super R,E> argument type, Record.map() takes RecordMapper<Record,E> , because Record has no recursive generic type definition for R .

In other words, if you want to reuse the same mapper for both Result.map() and Record.map() , unfortunately, you will need to make it a RecordMapper<Record, E> , which means you'll lose some of the type safety on the record type.

A workaround would be to create a new result just for the sake of mapping:

Result<TableRecord> result = DSL.using(configuration).newResult(TABLE);
result.add(record);
Something pojo = result.map(mapper).get(0);

Answer 2

An alternative workaround to the one provided by Lukas Eder could be to use the mapper directly:

TableRecord record = create.selectFrom(TABLE).fetchOne();    
Something pojo = mapper.map(record);