DbOom: Mapping to a bean

There are cases when you have to write complex queries with some calculations, string manipulation, etc. when some result set columns are calculated and not simple table columns values. The question is how to map such columns using DbOom and template SQL.

One answer is simple: you can map such result set into simple types, like Integer, String, etc. classes. However, it would be more convenient if you can map such result into a bean.

To do that, you can create a view in database. However, there are some cases when you can't use views. Do not worry, DbOom can help you anyway. Just use $C template-sql macro as alias column name.

Let's focus on the following sql:

    select g.ID + 10, UCASE(g.NAME), g.* from GIRL g where g.ID=1

Two first columns are calculated ones. As said, we can map this result to: Long.class, String.class, Girl.class. But lets see how we can map first two columns into the some Bean1 class, a pure POJO.

First thing is to annotate Bean1 class with @DbTable and @DbColumn annotations, as it is a mapped bean.

Then, you can write above query using the following template-sql:

    select $g.id + 10 as $C{Bean1.sum}, UCASE($g.name) as $C{Bean1.bigName}, $C{g.*}
    from $T{Girl g}
    where $g.id=1

The key point here is to map columns using $C macro and the bean name.