Entity inheritance an error while refreshing with EntityManager - mysql

Question

When using entity inheritance hierarchy witch #DiscriminatorColumn storing DiscriminatorType.STRING values in MySQL ENUM. Below code example:
#Entity
#DiscriminatorColumn(name ="account_type", discriminatorType = DiscriminatorType.STRING,
columnDefinition = "ENUM('natural_person', 'firm', 'provider', 'employee', 'administrator', 'moderator', 'user')")
#DiscriminatorValue("user")
public class User implements Serializable { ... }
and inherited entity:
#Entity
#DiscriminatorValue("firm")
public class Firm extends User { ... }
when I create Firm object or removes everything works ok, even when I find it with EntityManager, but if I make EnityManager.refresh(firm) than there is an error complaining about:
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'firm0_.account_type' in 'field list'
UPDATE:
When I changed this columnDefinition of #DescriminatorColumn by deleting it and storing strings "firm", "user", ERROR ALSO OCCURES!
UPDATE 2:
I have a little suggestion that as Firm extends UserAccount this discriminator column account_type should be in user_account table. So error firm0.account_type seems stupid as it search this column in user_account.account_type!
I have another subclass Person and it persists and than saves OK, but Firm only persists, removes but DON'T REFRESH!
UPDATE 3:
Found sql log like this:
Hibernate:
insert
into
user_account
(activation_code, email, last_failed_login, last_logged, login, password, registration_date, account_type)
values
(?, ?, ?, ?, ?, ?, ?, 'firm')
Hibernate:
insert
into
firm
(address_city, address_country, address_office_no, address_building_no, address_state, address_street, address_zip_code, client_id, company_number, name, phone_number, skype_name, statistic_number, vatin, user_id)
values
(?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
Hibernate:
select
firm0_.user_id as user_id2_14_0_,
firm0_1_.activation_code as activati3_14_0_,
firm0_1_.email as email4_14_0_,
firm0_1_.last_failed_login as last_fai5_14_0_,
firm0_1_.last_logged as last_log6_14_0_,
firm0_1_.login as login7_14_0_,
firm0_1_.password as password8_14_0_,
firm0_1_.registration_date as registra9_14_0_,
firm0_.address_city as address_1_3_0_,
firm0_.address_country as address_2_3_0_,
firm0_.address_office_no as address_3_3_0_,
firm0_.address_building_no as address_4_3_0_,
firm0_.address_state as address_5_3_0_,
firm0_.address_zip_code as address_7_3_0_,
firm0_.client_id as client_15_3_0_,
firm0_.company_number as company_8_3_0_,
firm0_.name as name9_3_0_,
firm0_.skype_name as skype_n11_3_0_,
firm0_.statistic_number as statist12_3_0_,
firm0_.vatin as vatin13_3_0_,
firm0_2_.corporation_id as corporat5_8_0_,
firm0_2_.description as descript1_8_0_,
firm0_2_.name as name2_8_0_,
firm0_2_.type as type3_8_0_,
firm0_.account_type as account_1_14_0_
from
firm firm0_
inner join
user_account firm0_1_
on firm0_.user_id=firm0_1_.user_id
left outer join
provider firm0_2_
on firm0_.user_id=firm0_2_.provider_id
where
firm0_.user_id=?
Jun 10, 2015 5:37:16 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
WARN: SQL Error: 1054, SQLState: 42S22
Jun 10, 2015 5:37:16 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions
ERROR: Unknown column 'firm0_.account_type' in 'field list'
Jun 10, 2015 5:37:16 PM org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl stop
INFO: HHH000030: Cleaning up connection pool

Answer 1

I'm guessing that when JPA generates the DDL it is using the columnDefinition string as a literal for the column definition. Thus, it should be "account_type ENUM('natural_person', 'firm', 'provider', 'employee', 'administrator', 'moderator', 'user')"

Answer 2

Ok It seems I found solution but it is odd, and I will be testes it later.
private String accountType;
#Column(name = "account_type", insertable = false, updatable = false)
public String getAccountType() {
return accountType;
}
public void setAccountType(String accountType) {
this.accountType = accountType;
}
I have added this code into UserAccount (superclass - root of inheritance hierarchy), where discriminator column is defined... BUT it seems odd behaviour to define explicite discriminator column in entity! I read that it is anit-pattern, not recommanded to add, and moreover to use such discriminator column in code...