JDBI, retrieve data with sql query into customized object(constructor) instead of Map
So when we use JDBI to query from database, it is getting it into a Map<String, Object> type.
I want to get it as my customized object (constructor) instead of Map<String, Object>.
DBI dbi = establishConnection(url, userName, passWord);
Handle handle = dbi.open();
List<Map<String, Object>> rs = handle.select("select * from sometable");
Instead I want to use:
List<customizedObject> rs = handle.select("select * from sometable");
Where customizedObject class is an object that contains all the column properties with it.
Is there any way to do this? I found some relative documentation, but I cannot really understand the implementation.
Answer
Please also see the previous page in the documentation that shows how to link your Handle or DBI with the mappers.
Essentially, you need a mapper to convert the ResultSet to the desired object and an interface to refer to the mapper.
Let's assume a minimal example. First the mapper needs to be provided:
public class CustomizedObjectMapper implements ResultSetMapper<customizedObject> {
@Override
public customizedObject map(int index, ResultSet r, StatementContext ctx)
throws SQLException {
return new customizedObject(r.getString("uuid"), r.getString("other_column"));
}
}
Then we need an interface to define which query provides the data that is passed to the mapper class. One result row leads to one invocation of CustomizedObjectMapper.map(...):
@RegisterMapper(CustomizeObjectMapper.class)
public interface CustomizeObjectQuery {
@SqlQuery("Select uuid, other_column from schema.relation")
List<customizedObject> get();
}
Finally, the objects can be retrieved: List<customizedObject> test = dbi.open(CustomizeObjectQuery.class).get().
Your can also put the components together on an individual basis like so and omit the interface:
dbi.open().createQuery("Select uuid, other_colum from schema.relation").map(new EventMapper()).list()