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How to use derived columns in Spring Data JPA associations

I have an entity TeamActivity:
#Entity
#Table(name = "teams_to_activities")
public class TeamActivity {
#Column(name = "scope_id", nullable = false)
private String scopeId;
#Column(name = "team_id", nullable = false)
private String teamId;
#Column(name = "activity_set_id", nullable = false)
private String activitySetId;
#Id
#Column(name = "scoped_team_activity_id", nullable = false)
private String scopedTeamActivityId;
}
And another entity ActivitySet:
#Entity
#Table(name = "activity_sets")
public class ActivitySet {
#Column(name = "scope_id", nullable = false)
private String scopeId;
#Column(name = "name", nullable = false)
private String name;
#Column(name = "description", nullable = false)
private String description;
#Id
#Column(name = "scoped_activity_set_id", nullable = false)
private String scopedActivitySetId;
}
There's no index on any other column besides the PK in both tables.
There's no FK constraint creating a relationship between these tables whatsoever. I have no idea why as this is a legacy system.
Technically, if I fetch a TeamActivity record, I can pick the scope_id and activity_set_id from it and combine them to form a scoped_activity_set_id which would be a valid PK to fetch the corresponding ActivitySet.
I know that TeamActivity -> ActivitySet is a N -> 1 association
I would like to leverage Spring Data JPA features to create an association from TeamActivity to ActivitySet such that when I fetch a TeamActivity from TeamActivityRepository, the corresponding ActivitySet is also returned.
I have created an association like this before using a combination of #JoinColumn and #MapsId but there was actually a single FK to use which is different here where source table has 2 columns I can combine to get the target's key.

If you are fully in control of the database, I may propose you create a Materialized View with the contents you desire from both tables and handle it as any other table with JPA, i.e, create #Entity model and CrudRepository<MVTeamActivitySet, String>.
If you are not fully in control of the database, one easy way to achieve it is to simply create a method that internally executes two lookup queries and retrieves the expected model you want. You will still be using using JPA correctly.
Querying two tables and joining desired fields in the code layer is quite common with denormalized DBs, sometimes you want to avoid the overhead of a Materialized View.
#Override
public TeamActivitySetDto findById(String scopedTeamActivityId) throws DemoCustomException {
Optional<TeamActivity> teamActivityEntity = teamActivityDao.getById(scopedTeamActivityId);
if(teamActivityEntity.isEmpty()) {
throw new DemoCustomException("teamActivity record not found");
}
String scopedActivitySetId =
teamActivityEntity.get().getScopeId() + ":" + teamActivityEntity.get().getActivitySetId();
Optional<ActivitySet> activitySetEntity = activitySetDao.getById(scopedActivitySetId);
if(activitySetEntity.isEmpty()) {
throw new DemoCustomException("activitySet record not found");
}
return TeamActivitySetDto.builder()
.description(activitySetEntity.get().getDescription())
.name(activitySetEntity.get().getName())
.scopedActivitySetId(activitySetEntity.get().getScopedActivitySetId())
.activitySetId(teamActivityEntity.get().getActivitySetId())
.scopedTeamActivityId(teamActivityEntity.get().getScopedTeamActivityId())
.scopeId(teamActivityEntity.get().getScopeId())
.teamId(teamActivityEntity.get().getTeamId())
.build();
}

How to Include non-matching id in JPA OneToOne mapping

So I have a table with a column that has non-foreign key (no actual table reference) reference on another table but the other table might not have a matching row
class Component {
#OneToOne(fetch = FetchType.EAGER, optional = false)
#JoinColumn(name = "PART_ID", referencedColumnName="PART_ID", nullable = true, insertable = false, updatable = false)
#NotFound(action = NotFoundAction.IGNORE)
private Part part
#Id
#Column(name = "COMPONENT_ID")
private Long id;
}
Part class
class Part {
#Id
#Column(name = "PART_ID")
private Long id;
private String name;
}
without this #NotFound(action = NotFoundAction.IGNORE) I am getting an error
but with this I am not getting an error and get null value but I need the id to be present
e.g) I am looking for this
{"component": {"id":12, "part":{"id":100,"name":null}}}
but I am getting this (if no match)
{"component": {"id":12, "part":null}}
but I am getting this (if match)
{"component": {"id":12, "part":{"id":100,"name":"part_name"}}}
Tried with nullable=false and some combinations for updatable and insertable and still nothing works

If table has reference on another table but the other table might not have a matching row , the database structure is probably broken.
Do you really need what you're asking for?
The database has 2 part_id. One in Component and the other in Part. Java code has only one - Part.
You can make an additional field
сlass Component {
private Long partId;
...
and in the #PostLoad method - create a new Part with the desired id.
#PostLoad
public void postLoad(){
if(part == null && partId!=null){
part= new Part();
part.setId(partId)
}
}
}

JPA Entity - How to update a child entity field based on its parent field

I am currently stuck on an issue of updating a parent entity field and getting the update to cascade to all its children's fields.
Here is an example of what I am trying to accomplish:
User.java
#Entity
public class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#Column(nullable = false, columnDefinition = "TINYINT(1) default false")
private Boolean archived = Boolean.FALSE;
#OneToMany(mappedBy = "user")
private Set<Invoice> invoices = new HashSet<Invoice>();
// Setters & Getters
}
Invoice.java
#Entity
public class Invoice{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#Column(nullable = false, columnDefinition = "TINYINT(1) default false")
private Boolean archived = Boolean.FALSE;
#ManyToOne(mappedBy = "invoices")
#JoinColumn(nullable = false)
private User user;
// Setters & Getters
}
When I update the archived value to true. I want all the invoices to also be updated to true as well.
I.E
public Boolean archiveUserById(Integer id) {
User user= entity_manager.find(User.class, id);
Boolean result = false;
if(auction != null) {
// This should cascade to all the invoices as well and update their archived fields to true as well
user.setArchived(true);
try {
entity_manager.getTransaction().begin();
entity_manager.merge(auction);
entity_manager.getTransaction().commit();
result = true;
} catch(Exception e) {
e.printStackTrace();
}
}
return result;
}
I've tried using cascade = CascadeType.PERSIST and #JoinTable(....) with all the referenced columns, but they are still failing to update the fields correctly.
To clarify is there a way to update a child's field through its parents' update with a Cascade effect?
Thank-you for the help.
EDIT
To clarify my question, I am trying to add a constraint cascade effect when a field on the parent entity is updated to reflect on the child entity's same field. I am trying to avoid any logic within the Entity itself. Is there a way to do this through annotations only?
Something to the same effect as this:
ALTER TABLE `child` ADD CONSTRAINT `childs-archived-mirrors-parent`
FOREIGN KEY (`archived`, `parentId`)
REFERENCES `parent`(`archived`, `id`)
ON DELETE RESTRICT ON UPDATE CASCADE;

try adding #PreUpdate method on parent where you manually change children inside the list.

Thanks for all your help.
I ended up finding a solution. I created a custom foreign key definition that will cascade any update on the archived field to its child entities.
Below is how I accomplished that.
#Entity
public class Invoice{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#Column(nullable = false, columnDefinition = "TINYINT(1) default false")
private Boolean archived = Boolean.FALSE;
#ManyToOne(mappedBy = "invoices")
#JoinColumn(nullable = false, foreignKey = #ForeignKey(foreignKeyDefinition = "FOREIGN KEY (archived, user_id) REFERENCES user(archived, id) ON DELETE RESTRICT ON UPDATE CASCADE"))
private User user;
// Setters & Getters
}

How to delete Hibernate #Embeddables containing nullable fields?

When deleting an #Embeddable object, I run into some problems.
I have the following domain classes: SwitchVoipTrunkGroup and PrioritizedCodec. The latter contains several fields that are nullable.
class SwitchVoipTrunkGroup {
//...
#CollectionOfElements(fetch = FetchType.LAZY)
#JoinTable(
name = "SWITCH_VOIP_TKG_CODEC",
joinColumns = #JoinColumn(name = "FK_SWITCH_VOIP_TKG_ID")
)
#ForeignKey(name = "FK_CODEC_SWITCH_VOIP_TKG")
private Set<PrioritizedCodec> prioritizedCodecs = new HashSet<PrioritizedCodec>();
//...
}
#Embeddable
public class PrioritizedCodec {
#Column(name = "PRIORITY")
private String priority;
#Column(name = "FAX_MODE")
private String faxMode;
//... some more columns ...
}
When I edit SwitchVoipTrunkGroup's prioritizedCodecs field (e.g. by deleting an entry) and save the entity, I see the following in my Hibernate logging:
13:54:31,919 INFO [STDOUT] Hibernate: delete from T_SWITCH_VOIP_TKG_CODEC where
fk_switch_voip_tkg_id=? and fax_mode=? and priority=?
From this question I understand why Hibernate uses all the fields in the where clause. However, this gives problems: in case some of these fields are empty, the query will look like so:
delete from T_SWITCH_VOIP_TKG_CODEC where fk_switch_voip_tkg_id=1 and fax_mode = ''
and priority =''
This will however not delete any records, as what is really necessary is for Hibernate to check for NULL iso for an empty string. For example:
delete from T_SWITCH_VOIP_TKG_CODEC where fk_switch_voip_tkg_id=1 and fax_mode
IS NULL and priority IS NULL
(cf. here for more info on why checking for an empty string does not suffice)
Any ideas on how to tackle this? Many thx!

I suggest to normalize your database, so both your classes become entities, and then to setup One-to-Many relation between SwitchVoipTrunkGroup and PrioritizedCodec, then you may setup cascading rules so Hibernate automatically updates collection of elements of PrioritizedCodec type, when you persist instance of SwitchVoipTrungGroup.
#Entity
class SwitchVoipTrunkGroup {
//...
#OneToMany(cascade = {CascadeType.MERGE, CascadeType.PERSIST}, orphanRemoval = true)
#JoinColumn(name = "switchVoipTrunkGroup_id")
#ForeignKey(name = "FK_PrioritizedCodec_SwitchVoipTrunkGroup")
private Set<PrioritizedCodec> prioritizedCodecs = new HashSet<PrioritizedCodec>();
//...
}
#Entity
public class PrioritizedCodec {
#Column(name = "PRIORITY")
private String priority;
#Column(name = "FAX_MODE")
private String faxMode;
//... some more columns ...
}
#Serice("someService")
public class SomeService {
#Autowired
private SwitchVoipTrunkGroupDao trunkDao;
public SwitchVoipTrunkGroup doOperation("criteria") {
SwitchVoipTrunkGroup tg = trunkDao.find("criteroa");
tg.getPrioritizedCodecs().[remove(2)]; //remove should be implemened, that is just lame statement
tg.getPrioritizedCodecs().get(5).setFaxMod("ENABLED");
return trunkDao.save(tg); //hibernate will remove missing elements from PrioritizedCodec table, and will update necessary entities.
}
}
Alternatively, you may specify default values for priority and faxMode fields via attributes of #Column annotation and enforce nullable constraints
#Column(columnDefinition = "VARCHAR(20) default 'NONE'", nullable = false)
private String faxMode;

Need an example of a primary-key #OneToOne mapping in Hibernate

Can somebody please give me an example of a unidirectional #OneToOne primary-key mapping in Hibernate ? I've tried numerous combinations, and so far the best thing I've gotten is this :
#Entity
#Table(name = "paper_cheque_stop_metadata")
#org.hibernate.annotations.Entity(mutable = false)
public class PaperChequeStopMetadata implements Serializable, SecurityEventAware {
private static final long serialVersionUID = 1L;
#Id
#JoinColumn(name = "paper_cheque_id")
#OneToOne(cascade = {}, fetch = FetchType.EAGER, optional = false, targetEntity = PaperCheque.class)
private PaperCheque paperCheque;
}
Whenever Hibernate tries to automatically generate the schema for the above mapping, it tries to create the primary key as a blob, instead of as a long, which is the id type of PaperCheque. Can somebody please help me ? If I can't get an exact solution, something close would do, but I'd appreciate any response.

I saved this discussion when I implemented a couple of #OneToOne mappings, I hope it can be of use to you too, but we don't let Hibernate create the database for us.
Note the GenericGenerator annotation.
Anyway, I have this code working:
#Entity
#Table(name = "message")
public class Message implements java.io.Serializable
{
#OneToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
#PrimaryKeyJoinColumn(name = "id", referencedColumnName = "message_id")
public MessageContent getMessageContent()
{
return messageContent;
}
}
#Entity
#Table(name = "message_content")
#GenericGenerator(name = "MessageContent", strategy = "foreign",
parameters =
{
#org.hibernate.annotations.Parameter
(
name = "property", value = "message"
)
}
)
public class MessageContent implements java.io.Serializable
{
#Id
#Column(name = "message_id", unique = true, nullable = false)
// See http://forum.hibernate.org/viewtopic.php?p=2381079
#GeneratedValue(generator = "MessageContent")
public Integer getMessageId()
{
return this.messageId;
}
}

Your intention is to have a 1-1 relationship between PaperChequeStopMetaData and PaperCheque? If that's so, you can't define the PaperCheque instance as the #Id of PaperChequeStopMetaData, you have to define a separate #Id column in PaperChequeStopMetaData.

Thank you both for your answers. I kept experimenting, and here's what I got working :
#Entity
#Table(name = "paper_cheque_stop_metadata")
#org.hibernate.annotations.Entity(mutable = false)
public class PaperChequeStopMetadata implements Serializable, SecurityEventAware {
private static final long serialVersionUID = 1L;
#SuppressWarnings("unused")
#Id
#Column(name = "paper_cheque_id")
#AccessType("property")
private long id;
#OneToOne(cascade = {}, fetch = FetchType.EAGER, optional = false, targetEntity = PaperCheque.class)
#PrimaryKeyJoinColumn(name = "paper_cheque_id")
#JoinColumn(name = "paper_cheque_id", insertable = true)
#NotNull
private PaperCheque paperCheque;
#XmlAttribute(namespace = XMLNS, name = "paper-cheque-id", required = true)
public final long getId() {
return this.paperCheque.getId();
}
public final void setId(long id) {
//this.id = id;
//NOOP, this is essentially a pseudo-property
}
}
This is, by all means, a disgusting hack, but it gets me everything I wanted. The paperCheque property accessors are as normal (not shown). I've run into this kind of unidirectional OneToOne mapping problem before and settled for much worse solutions, but this time I decided I was going to figure out out, so I kept hacking away at it. Once again, thank you both for your answers, it's much appreciated.

Just updating this question for future views.
When this question was made i think there wasn't a proper solution for this problem. But since JPA 2.0 you can use #MapsId to solve this problem.
Reference with proper explanation: https://vladmihalcea.com/the-best-way-to-map-a-onetoone-relationship-with-jpa-and-hibernate/

You should stay away from hibernate's OneToOne mapping, it is very dangerous. see http://opensource.atlassian.com/projects/hibernate/browse/HHH-2128
you are better off using ManyToOne mappings.