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Select few among all the nested entities : SPRING JPA

I have a scenario like below.
Lets say EntityA has three nested entities EntityB, EntityC, EntityD. And all of EntityB, EntityC, EntityD has several nested entities inside them.
But while selecting for EntityA it selects the whole tree of nested entities. Whereas I want to fetch a specific branch. Lets say only EntityA, EntityB and all sub entities of EntityB are to be fetched leaving EntityC and EntityD back then I am not sure how to do that. As spring jpa brings all the nested objects back to me.
I am using below collection mapping.
#Entity
#Table(name = "customer_party_mapping")
#Data
public class CustomerPartyMappingEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Integer id;
#Column(name = "customer_id")
private Integer custmerId;
#Column(name = "orgtype_id")
private Integer orgTypeId;
#OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL )
#JoinColumn(name = "customer_party_mapping_id")
#Fetch(value = FetchMode.SUBSELECT)
private List<CustomerPartyBookingLocationEntity> customerPartyBookingLocation=new ArrayList<CustomerPartyBookingLocationEntity>();
#OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL )
#JoinColumn(name = "customer_party_mapping_id")
#Fetch(value = FetchMode.SUBSELECT)
private List<CustomerPartyFieldMappingEntity> customerPartyFieldMappingEntity=new ArrayList<CustomerPartyFieldMappingEntity>();
#OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL )
#JoinColumn(name = "customer_party_mapping_id",referencedColumnName="id")
#Fetch(value = FetchMode.SUBSELECT)
private List<CustomerPartyOtherDocumentEntity> otherDocumentsList=new
ArrayList<>();
#OneToOne( cascade={ CascadeType.PERSIST, CascadeType.MERGE })
#JoinColumn(name = "customer_name_screening_id", referencedColumnName="id")
private CustomerNameScreeningEntity customerNameScreeningEntity;
#OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL )
#JoinColumn(name = "customer_party_mapping_id")
#Fetch(value = FetchMode.SUBSELECT)
private List<CustomerDocInfoTrackingEntity> customerDocInfoTrackingList=new
ArrayList<CustomerDocInfoTrackingEntity>();
}
And I am calling
List<CustomerPartyMappingEntity> customerPartyMappingEntityList = customerPartyMappingRepository.findByCustmerId(customerid);
It gets all the nested mapped list of entities wheras I need only CustomerPartyMappingEntity and its list of customerPartyFieldMappingEntity nested object.
Any help will be appreciated.

First use FetchType.LAZY for nested entity.
Then you can use #EntityGraph to fetch nested entity by name and their nested entity using their name with . in the repository. You use to just specify the nested property in attributePaths like
#EntityGraph(attributePaths = {"customerPartyBookingLocation"})
And the nested property of customerPartyBookingLocation like
#EntityGraph(attributePaths = {"customerPartyFieldMappingEntity.subField"})
Example:
#EntityGraph(attributePaths = {"customerPartyBookingLocation", "customerPartyFieldMappingEntity.subField"})
List<CustomerPartyMappingEntity> findByCustmerId(Integer customerid);
Note: You can't use #EntityGraph with #Query annotation

If your entities are really setup correctly, see for instance the subselect example here and remove your EAGER (you are currently instructing hibernate to fetch all these fields upon entity initialization). It should work.

Get id's of a ManyToMany mapping table

I'm writing an API using Spring Boot and Hibernate where my persisted entity objects are also used as DTOs sent to and from the client. This is a simplified version of a typical entity I use:
#Entity
#Table(name = "STUDENT")
public class Student {
#Id
#GeneratedValue
#Column(name = "ID")
private Long id;
#ElementCollection
#CollectionTable(name = "GROUP_STUDENT",
joinColumns = #JoinColumn(name = "GROUP_ID"))
#Column(name="STUDENT_ID")
private Set<Long> groupIds;
#JsonIgnore
#ManyToMany(fetch = FetchType.LAZY)
#JoinTable(name="GROUP_STUDENT",
joinColumns = #JoinColumn(name="GROUP_ID"),
inverseJoinColumns = #JoinColumn(name="STUDENT_ID")
)
private Set<Group> groups = new HashSet<>();
// getters and setters
}
and this is the associated class:
#Entity
#Table(name = "GROUP")
public class Group {
#Id
#GeneratedValue
#Column(name = "ID")
private Long id;
#JsonIgnore
#ManyToMany(fetch = FetchType.LAZY, mappedBy = "groups")
private Set<Student> students = new HashSet<>();
// getters and setters
}
As you can see, there is a #ManyToMany association between Student and Group.
Since I send objects like these to the client, I choose to send only the id's of the associations and not the associations themselves. I've solved this using this answer and it works as expected.
The problem is this. When hibernate tries to persist a Student object, it inserts the groups as expected, but it also tries to insert the groupIds into the mapping table GROUP_STUDENT. This will of course fail because of the unique constraint of the mapping table composite id. And it isn't possible to mark the groupIds as insertable = false since it is an #ElementCollection. And I don't think I can use #Formula since I require a Set and not a reduced value.
This can of course be solved by always emptying either the groups of the groupIds before saving or persisting such an entity, but this is extremely risky and easy to forget.
So what I want is basically a read only groupIds in the Student class that loads the data from the GROUP_STUDENT mapping table. Is this possible? I'm grateful for any suggestions and glad to ellaborate on the question if it seems unclear.

I've managed to solve this by making the id-collection #Transient and populating it using #PostLoad:
#Entity
#Table(name = "STUDENT")
public class Student {
#PostLoad
private void postLoad() {
groupIds = groups.stream().map(Group::getId).collect(Collectors.toSet());
}
#Id
#GeneratedValue
#Column(name = "ID")
private Long id;
#Transient
private Set<Long> groupIds;
#JsonIgnore
#ManyToMany(fetch = FetchType.LAZY)
#JoinTable(name="GROUP_STUDENT",
joinColumns = #JoinColumn(name="GROUP_ID"),
inverseJoinColumns = #JoinColumn(name="STUDENT_ID")
)
private Set<Group> groups = new HashSet<>();
// getters and setters
}

Jpa persisting an entity after setting id to zero

I have the following three entities
#Entity
class Session {
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, orphanRemoval=true)
#JoinColumn(name="session_id", referencedColumnName="id")
private List<Testcase> testcases;
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, orphanRemoval=true)
#JoinColumn(name="session_id", referencedColumnName="id")
private List<SessionChart> sessionCharts;
}
#Entity
class SessionChart {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, orphanRemoval=true)
#JoinColumn(name="sessionChart_id", referencedColumnName="id")
private List<ChartMeasurement> chartMeasurement;
}
#Entity
class ChartMeasurement {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
#ManyToOne
#JoinColumn(name = "testcase_id", nullable=true, referencedColumnName = "id")
private Testcase testcase;
}
and its corresponding getters and setters. Creating a new session and persisting it with out any session charts and chart measurements works great. But I have a save as functionality when I can open a previous saved session from a different user and rename it (change the owner as me) and resave it thus creating a new database record. I do this by setting id 0 to the entity and all its sub entities, that is Testcases list sessionCharts list and all chartMeasurement entitites inside sessionCharts list. But when trying to persist I get the following error
object references an unsaved transient instance - save the transient instance before flushing : ChartMeasurement.testcase -> Testcase
How can I overcome this behavior?

I'm going to assume you are using JPA and thus are using an javax.persistence.EntityManager instance.
I would suggest detaching the object before changing the ID's and performing a persist.
For example,
entityManager.detach(instanceOfYourObjectHere);
What's happening is that the Session is holding a reference to your object instance and is confused as you have changed the primary keys.

JPA CascadeType.REMOVE not working

I have two entities Business which is composed of a list of Departments
#Entity
#Table(name = "Business")
public class Business implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "Id")
private Long id;
#OneToMany(mappedBy = "business",
cascade = {CascadeType.PERSIST, CascadeType.REMOVE})
private List<Department> departments;
#OneToMany(mappedBy = "business", orphanRemoval = true,
cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE})
private List<Process> processs;
#ManyToMany
private List<Competence> competences;
}
#Entity
#Table(name = "Department")
public class Department implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#OneToMany(mappedBy = "father",
cascade = {CascadeType.PERSIST, CascadeType.REMOVE})
private List<Department> departments;
}
When I try to remove a business instance I get a Mysql Exception
Cannot delete or update a parent row: a foreign key constraint fails (evac_java.Department, CONSTRAINT FK_Department_Business FOREIGN KEY (Business) REFERENCES Business (Id)):HY000 - null
Which means I can't delete the business instance because it has departments associated with it, but a department cannot exists by itself so I want to delete all business's departments when it gets removed. I thought I would achieve this by adding cascade = CascadeType.REMOVE to the #OneToMany annotation in the business entity, but it does not work.
I did a search on the net and I found a lot of questions similar to this one on stackoverflow but they all suggest the same: add cascade = CascadeType.REMOVE or CascadeType.ALL
So I'm wondering if I'm missing somethig.
I'm using Glassfish 4.1 and EclipseLink
I tried with
#OneToMany(mappedBy = "business", orphanRemoval = true)
private List<Department> departments;
on the business entity but it does not work either
Here's the method I'm using to remove entities which is declared in an abstract class
public void remove(T entity) {
getEntityManager().remove(getEntityManager().merge(entity));
}

JPA can only remove and cascade the remove over entities it knows about, and if you have not been maintaining both sides of this bidirectional relationship, issues like this will arise. If the collection of departments is empty, try an em.refresh() before the remove, forcing JPA to populate all relationships so that they can be correctly removed, though it is better to maintain both sides of the relationship as changes are made to avoid the database hit.

Troubles with cascade deleting objects with parent-child relations to the same table

First of all, sorry for my English.
So, I'm working with MS SQL Server with hibernate and i faced with a problem.
I have next mapping of one of the tables in my DB:
#Entity(name = " ... ")
public class Entity extends BaseEntity implements Comparable {
#Id
#Column(name = "...")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#Column(name = "parent_entity_id", insertable = false, updatable = false)
private Integer parentId;
#ManyToOne(fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST})
#JoinColumn(name = "parent_entity_id")
private Entity parent;
#OneToMany(mappedBy = "parent", fetch = FetchType.LAZY, cascade = {CascadeType.REMOVE}, orphanRemoval = true)
private Set<Entity> children;
//other fields, setters, getters
}
That means, that my Entity objects can have children, which are also an Entity objects.
So, my problems is that I can't correctly delete parent with all his children. When I try to remove parent, i get an SQL error:
The DELETE statement conflicted with the SAME TABLE REFERENCE
So, any ideas, how to solve this problem?

You have a foreign key defined between parent_entity_id and id. Set it to allow cascading deletes: deleting a parent will delete all it's children, and all their children et cetera.
Be sure you actually want this to happen!