#Enumerated Mapping with Postgresql Enum - postgresql

Question

I created a simple entity called Agent that have an enumerated category. I already know that JPA will not map this enum with Postgresql type enum so I tried to force this mapping.
What I Have:
Java Parts: in the java part we've defined the Person.java entity and the category enumerated class.
Person.java
#Entity
public class Agentimplements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Column(length = 50, nullable = false)
private String code;
#Column(length = 50, nullable = false)
private String first_name;
#Column(length = 50, nullable = false)
private String family_name;
#Enumerated(EnumType.STRING)
#Column(nullable = false)
private TypeEntree category;
}
CategoryEn.java
public enum CategoryEn{
CUSTOMER,
PROVIDER,
DRIVER
}
Sql Forcing:
CREATE TYPE category_enum AS ENUM ('CUSTOMER','PROVIDER','DRIVER');
CREATE FUNCTION dummy_cast(varchar) RETURNS category_enum AS $$
SELECT CASE $1
WHEN 'CUSTOMER' THEN 'CUSTOMER'::category_enum
WHEN 'PROVIDER' THEN 'PROVIDER'::category_enum
WHEN 'DRIVER' THEN 'DRIVER'::category_enum
END;
$$ LANGUAGE SQL;
CREATE CAST (varchar AS category_enum) WITH FUNCTION dummy_cast(varchar) AS ASSIGNMENT;
ALTER TABLE public.agent
ALTER COLUMN category
SET DATA TYPE category_enum
USING agent::text::category_enum;
Until here, everything is working fine, but when I try to execute this query in the the AgentFacade:
String jpql ="SELECT a FROM Agent a"
+ " WHERE a.category = :cat";
Query query = em.createQuery(jpql);
query.setParameter("cat", CategoryEn.DRIVER);
I'm having the following error:
Caused by: javax.persistence.PersistenceException: Exception [EclipseLink-4002]
(Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd):
org.eclipse.persistence.exceptions.DatabaseException Internal
Exception: org.postgresql.util.PSQLException: ERREUR: operator does not exist : category_enum= character varying
Indication :No operator matches the given name and argument type(s). You might need to add explicit type casts
My questions are:
Why I am having this error ?
Can I solve this error ? How?
Why the JPA doesn't have a tool that map automatically a Java enum to an Sql type enum ?
PS: I've already seen almost all the stackoverflow questions/answers that are similare to this topic

Answer 1

You are getting this error because your driver/ORM is likely casting that parameter to varchar.
You could create operator for that comparison:
CREATE OR REPLACE FUNCTION texteq(
category_enum,
text)
RETURNS boolean AS $q$ SELECT texteq($1::text, $2) $q$
LANGUAGE SQL IMMUTABLE STRICT
COST 1;
CREATE OPERATOR =(
PROCEDURE = texteq,
LEFTARG = category_enum,
RIGHTARG = text,
COMMUTATOR = =,
NEGATOR = <>,
RESTRICT = eqsel,
JOIN = eqjoinsel,
HASHES,
MERGES);
I didn't test if it actually works in JOIN merges/hashes, but simple comparison looks fine.