jOOQ (http://www.jooq.org/) + Java 8 Rulez! = type-safe queries, shared behavior using traits

jooq-java8.java

public interface RepositoryTrait<TABLE extends TableImpl<RECORD>, RECORD extends Record, POJO> {
    DSLContext db();
    TABLE table();
}

public interface UpsertRepositoryTrait<TABLE extends TableImpl<RECORD>, RECORD extends Record, POJO> extends RepositoryTrait<TABLE, RECORD, POJO> {
    default int upsert(List<POJO> items) {
        if (items.size() < 1) {
            return 0;
        }

        TABLE t = table();
        RECORD record = t.newRecord();
        record.from(items.get(0), t.fields());

        InsertValuesStepN<RECORD> insert = db().insertInto(t).values(record.valuesRow().fields());

        for (POJO item : items.subList(1, items.size())) {
            record = t.newRecord();
            record.from(item, t.fields());
            insert = insert.values(record.valuesRow().fields());
        }

        return buildOnDuplicateKeyUpdate(insert.onDuplicateKeyUpdate()).execute();
    }

    InsertOnDuplicateSetMoreStep<RECORD> buildOnDuplicateKeyUpdate(InsertOnDuplicateSetStep<RECORD> step);
}

public class UserRepository implements UpsertRepositoryTrait<Users, UserRecord, User> {
    @Autowired DSLContext db;
    public DSLContext db() { return db; }
    public Users table() { return Tables.USERS; }
    public InsertOnDuplicateSetMoreStep<UserRecord> buildOnDuplicateKeyUpdate(InsertOnDuplicateSetStep<UserRecord> step) {
        Users t = table();
        return step
            .set(t.FIRST_NAME, MySQLDSL.values(t.FIRST_NAME))
            .set(t.LAST_NAME, MySQLDSL.values(t.LAST_NAME))
            .set(t.EMAIL, MySQLDSL.values(t.EMAIL));
    }
}