java - jooq cannot convert from class a to class b -

i have problem, think can easly solved, can't it.

i have class , b , class stored in postgres db:

public class a() {     private b b;     ... }  public class b() {     private string firstname;     private string lastname;     private string personid;     private string username; } 

in database, object of class b stored string username in entity. have object of class db in app, have read record , create object of class b. want create query jooq, jooq not know how convert string username instance of class b. how tell jooq how should map database object object of class a.

a class equivalent person , b class equivalent executor.

my query

return jooq.select()     .from(person)     .where(person.id.eq(id))     .fetchoneinto(person.class); 

this exception thrown query

caused by: org.jooq.exception.datatypeexception: cannot convert superadmin (class java.lang.string) class fi.ssm.oksa.domain.person.executor @ org.jooq.tools.convert$convertall.fail(convert.java:1118) ~[jooq-3.8.5.jar:na] ... 

i think should use http://www.jooq.org/doc/3.8/manual/code-generation/custom-data-type-bindings/ can't implement it.

there different ways solve this:

use jooq's undocumented (as of version 3.8) nested record mapping feature

jooq has undocumented feature in defaultrecordmapper allows nest result records when use of into(class) methods. have manually specify "path" of nested record if using ordbms nested records, such:

jooq.select(        person.first_name.as("executor.first_name"),        person.last_name.as("executor.last_name"),        person.person_id.as("executor.person_id"),        person.user_name.as("executor.user_name"))     .from(person)     .where(person.id.eq(id))     .fetchoneinto(person.class); 

when alias columns way, defaultrecordmapper search executor property in person class, , put trailing sub-path nested object.

in example, i'm going assume modified versions of classes:

// instead of public class person {     private executor executor;     ... }  // instead of b public class executor {     private string firstname;     private string lastname;     private string personid;     private string username; } 

override defaultrecordmapper

you can implement own algorithms mapping when using into(class) methods documented here:

http://www.jooq.org/doc/latest/manual/sql-execution/fetching/pojos-with-recordmapper-provider

use explicit record mapper:

of course, nothing forces rely on jooq's built-in automatic mapping features. write own algorithm this, instance:

jooq.select()     .from(person)     .where(person.id.eq(id))     .fetchone(r -> new person(new executor(r.get(person.first_name), ...));