Declare JPA entity for a tree element - jpa

Question

I do have a DB table with unidirectional trees. Leafs of these trees can have several children/parents.
Cycles are restricted.
Here is my DB table definition:
CREATE MULTISET TABLE WORKFLOW_SEQ_REL ,NO FALLBACK ,
NO BEFORE JOURNAL,
NO AFTER JOURNAL,
CHECKSUM = DEFAULT,
DEFAULT MERGEBLOCKRATIO
(
WORKFLOW_SEQ_ID INTEGER NOT NULL,
REL_WORKFLOW_SEQ_ID INTEGER NOT NULL,
JOB_ID BIGINT)
PRIMARY INDEX ( WORKFLOW_SEQ_ID );
As you can see it doesn't have a primary key right now. But it would appear later :) Really PK is: JOB_ID+PARENT_ID+CHILD_ID.
The idea is:
REL_WORKFLOW_SEQ_ID = PARENT
WORKFLOW_SEQ_ID = CHILD
JOB_ID = TREE_IDENTIFICATOR (a determinant to separate different trees stored
in one table).
I'm trying to declare a JPA entity:
#Entity
#Table(name="WORKFLOW_SEQ_REL")
public class EtlWorkflowSeqNode {
#EmbeddedId
public EtlWorkflowSeqNodeId etlWorkflowSeqNodeId;
//#Column(name="JOB_ID")
//public Integer jobId;
#Embeddable
class EtlWorkflowSeqNodeId{
#Column(name="JOB_ID")
public Integer jobId;
#ManyToOne(fetch = FetchType.EAGER)
#JoinColumn(name="REL_WORKFLOW_SEQ_ID")
//EtlWorkflowSeq.id = PK of EtlWorkflowSeq entity
public EtlWorkflowSeq parent;
#OneToMany(fetch=FetchType.EAGER /*, mappedBy="parent"*/)
#JoinColumn(name="WORKFLOW_SEQ_ID")
public Set<EtlWorkflowSeq> children;
}
}
And I gen an error:
Caused by: org.hibernate.AnnotationException: A Foreign key refering models.EtlWorkflowSeqNode from models.EtlWorkflowSeq has the wrong number of column.
should be 2
Here is EtlWorkflowSeq entity:
#Entity
#Table(name="WORKFLOW_SEQ")
public class EtlWorkflowSeq {
#Id
#Column(name="WORKFLOW_SEQ_ID")
public Integer id;
#OneToOne(fetch=FetchType.EAGER)
#JoinColumn(name="WORKFLOW_ID")
public EtlWorkflow etlWorkflow;
}
What do I do wrong?
UPD:
Here are table definitions:
--a bad design. PK should be: WORKFLOW_SEQ_ID + REL_WORKFLOW_SEQ_ID + JOB_ID
CREATE MULTISET TABLE WORKFLOW_SEQ_REL ,NO FALLBACK ,
NO BEFORE JOURNAL,
NO AFTER JOURNAL,
CHECKSUM = DEFAULT,
DEFAULT MERGEBLOCKRATIO
(
WORKFLOW_SEQ_ID INTEGER NOT NULL, --a ref to child
REL_WORKFLOW_SEQ_ID INTEGER NOT NULL, -- a ref to parent
START_TYPE_ID SMALLINT NOT NULL, -- a type of connection
DISABLE_START_TYPE_ID SMALLINT, -- other type of connection
JOB_ID BIGINT) -- a tree determinant,
PRIMARY INDEX ( WORKFLOW_SEQ_ID );
CREATE MULTISET TABLE WORKFLOW_SEQ ,NO FALLBACK ,
NO BEFORE JOURNAL,
NO AFTER JOURNAL,
CHECKSUM = DEFAULT,
DEFAULT MERGEBLOCKRATIO
(
WORKFLOW_SEQ_ID INTEGER NOT NULL, -- an id
WORKFLOW_ID BIGINT NOT NULL, -- a ref to original workflow, not interesting
IS_NAME VARCHAR(255) CHARACTER SET UNICODE NOT CASESPECIFIC, -- some name
INFO_SYSTEM_INST_CD VARCHAR(255) CHARACTER SET UNICODE NOT CASESPECIFIC, -- other name
DISABLE BYTEINT) -- so garbage
UNIQUE PRIMARY INDEX ( WORKFLOW_SEQ_ID ); -- it should also be a PK
The Idea is that several trees are stored in WORKFLOW_SEQ_REL
JOB_ID is a determinant for trees.
WORKFLOW_SEQ_ID, REL_WORKFLOW_SEQ_ID refer some cutomized template from REL_WORKFLOW_SEQ table.

Answer 1

I cannot help noticing that there is an inconsistency in your question.
You first state that:
Leafs of these trees can have several children/parents.
This in my believe makes the relationship between leafs many to many.
As I make of your question that EtlWorkflowSeq represent leafs, I think EtlWorkflowSeqNode represents the relationship between EtlWorkflowSeq objects?
However, the nodes point to one parent and many children.
You can use something like this to create something similar:
#Entity
#Table(name="WORKFLOW_SEQ")
public class EtlWorkflowSeq
{
#Id
#GeneratedValue
#Column(name="WORKFLOW_SEQ_ID")
public Integer id;
#ManyToOne
#JoinColumn(name="WORKFLOW_ID")
public EtlWorkflow etlWorkflow;
#ManyToMany
#JoinTable(name = "WORKFLOW_SEQ_REL")
private Set<EtlWorkflowSeq> children;
#ManyToMany(mappedBy = "children")
private Set<EtlWorkflowSeq> parents;
#ManyToOne
#JoinColumn(name = "JOB_ID", referencedColumnName = "id")
private Job job;
}
This would make EtlWorkflowSeqNode and EtlWorkflowSeqNodeId obsolete.
I also would like to state that when using an #Embeddable you should only use base types in them. Using other than base types is not possible/causes problems/is not standard (correct me if I'm wrong).
If you would like to use foreign keys in a composite primary key you can use this:
#Entity
public class Foo
{
#Id
private Long id;
}
#Entity
public class Bar
{
#EmbeddedId
private BarPK key;
#MapsId(value = "fooId")
#ManyToOne
#JoinColumns({
#JoinColumn(name = "foo_id", referencedColumnName = "id")
})
private Foo foo;
}
#Embeddable
public class BarPK
{
#Column(name = "id")
private Long id;
#Column(name = "foo_id")
private Long fooId;
}