I'm creating a simple REST application with dropwizard using JDBI. The next step is to integrate a new resource that has a one-to-many relationship with another one. Until now I couldn't figure out how to create a method in my DAO that retrieves a single object that holds a list of objects from another table.
The POJO representations would be something like this:
User POJO:
public class User {
private int id;
private String name;
public User(int id, String name) {
this.id = id;
this.name = name;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Account POJO:
public class Account {
private int id;
private String name;
private List<User> users;
public Account(int id, String name, List<User> users) {
this.id = id;
this.name = name;
this.users = users;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<User> getUsers() {
return users;
}
public void setUsers(List<User> users) {
this.users = users;
}
}
The DAO should look something like this
public interface AccountDAO {
@Mapper(AccountMapper.class)
@SqlQuery("SELECT Account.id, Account.name, User.name as u_name FROM Account LEFT JOIN User ON User.accountId = Account.id WHERE Account.id = :id")
public Account getAccountById(@Bind("id") int id);
}
But when the method has a single object as return value (Account instead of List<Account>) there seems to be no way to access more than one line of the resultSet in the Mapper class. The only solution that comes close I could find is described at https://groups.google.com/d/msg/jdbi/4e4EP-gVwEQ/02CRStgYGtgJ but that one also only returns a Set with a single object which does not seem very elegant. (And can't be properly used by the resouce classes.)
There seems to be a way using a Folder2 in the fluent API. But I don't know how to integrate that properly with dropwizard and I'd rather stick to JDBI's SQL object API as recommended in the dropwizard documentation.
Is there really no way to get a one-to-many mapping using the SQL object API in JDBI? That is such a basic use case for a database that I think I must be missing something.
All help is greatly appreciated,
Tilman