I want to convert the following mapping on courseDetails to manyToMany.
This is because I get an exception Found shared references to a collection: com.xyz.courseDetails and I assume this happens because the relation is not actually one to many in the database, since there are some course_detail tuples that has multiple courses.
#Entity
#Table(name = "courses")
public class Course
{
#Column(name = "course_detail_id")
private Long extendedCourseDetailId;
...
#OneToMany(fetch = FetchType.LAZY, targetEntity = CourseDetail.class, cascade = CascadeType.ALL)
#JoinColumn(name="id", referencedColumnName="course_detail_id")
private List<CourseDetail> courseDetails = new ArrayList<>();
}
Simply changing the annotation to ManyToMany does not work, JPA somehow couldn't find the related columns. Why? How can I do this?
What do you think of this :
Let's assume the entity CourseDetail has as ID :
public class CourseDetail
{
#Id
#Column(name = "cd_id")
private Long courseDetailId;
So this non tested code might help you.
where the table "course__course_detail" will be automatically created to hold the relationship with 2 columns : "course_id" and "coursedetail_id".
#Entity
#Table(name = "courses")
public class Course
{
#Id
#Column(name = "c_id")
private Long courseId;
// #Column(name = "course_detail_id") // I comment because I dont understand the purpose
// private Long extendedCourseDetailId;
...
#ManyToMany(fetch = FetchType.LAZY)
#JoinTable(name = "course__course_detail",
joinColumns = #JoinColumn(name = "course_id", referencedColumnName="c_id"),
inverseJoinColumns = #JoinColumn(name = "coursedetail_id", referencedColumnName="cd_id"),
)
private List<CourseDetail> courseDetails = new ArrayList<>();
}
PS: NOT TESTED
Feel free to tell me more in comments.
Related
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
}
When deleting a parent entity I also want to remove the associated child entities (from the database). I have tried to make use of cascade on remove as seen below but I must be doing something incorrectly.
When calling remove on the parent entity object, I recieve the error message: "The entity is still referenced elsewhere in the database". I can confirm that the only place where the entity is referenced elsewhere in the database is in the two tables below (if I manually delete the child row from the database, the remove call on the parent works fine). I have been reading about entity objects and trying different things for the last 9 hours. What am I doing wrong?
Here is my parent table:
#Entity
#Table(name = "TURTLE_LOOKUP")
public class TurtleLookup implements Serializable
{
#Basic(optional = false)
#Column(name = "TURTLEID")
private int turtleid;
#Basic(optional = false)
#Column(name = "TURTLE")
private String turtle;
#OneToMany(mappedBy = "turtleType", cascade = CascadeType.REMOVE)
List<TurtleReview> turtleReviews;
...
}
Here is my child table:
#Entity
#Table(name = "TURTLE_REVIEW")
public class TurtleReview implements Serializable
{
#Column(name = "TURTLE_REVIEW_ID")
private int turtleReviewId;
#Column(name = "TURTLE_YEAR")
private int turtleYear;
#ManyToOne(cascade = CascadeType.REMOVE, optional = false)
#JoinColumn(name = "TURTLE_ID", referencedColumnName = "TURTLEID")
private TurtleLookup turtleType;
#Column(name = "IS_COMPLETE")
private short isComplete;
...
}
EDIT/UPDATE:
If I change CascadeType.REMOVE to CascadeType.ALL, the TurtleReview entities are successfully deleted from the database when deleting the parent TurtleLookup entity object. However, when calling the below function to create a new TurtleReview entity object, JPA tries to insert a new TurtleLookup entity in to the database, which throws the exception: "Entry already resides within the DB. Transaction rolled back". Below is the code executed when creating a new TurtleReview entity.
public void setDatasetReviewComplete(TurtleLookup turtle, Short year, boolean isComplete)
{
TurtleReview turtleReview = getTurtleReview(turtle, year);
if (turtleReview == null)
{
turtleReview = new TurtleReview();
turtleReview.setTurtleYear(year)
turtleReview.setTurtleType(new a.b.entity.TurtleLookup(turtle.getId(), turtle.getValue()));
}
turtleReview.setIsComplete(isComplete ? (short)1 : 0);
entityManager.persist(turtleReview);
}
try change cascade value to all or all-delete-orphan
#OneToMany(mappedBy = "turtleType", cascade = CascadeType.REMOVE)
List<TurtleReview> turtleReviews;
...
}
There might be an issue with your domain model, a part that is left out in the question. Do you possibly have circular cascades? If you have a circle of cascades and some of them are CascadeType.REMOVE and some are CascadeType.PERSIST, then Hibernate (not sure about other JPA implementation) will just do.... nothing when you call the remove() method. Without an error or exception message.
Try with hibernate #Cascade annotation:
#Cascade(value = CascadeType.ALL)
#OneToOne(mappedBy = "turtleReview") // mappedBy name of TurtleRewiew object field in TurtleLookup entity class
private TurtleLookup turtleType;
If your relationship is oneToOne you can't have oneToMany to the other side and you can't have List<TurtleReview>. If your relationship is oneToMany then your entities will be for example:
#Entity
#Table(name = "TURTLE_LOOKUP")
public class TurtleLookup implements Serializable
{
#Basic(optional = false)
#Column(name = "TURTLEID")
private int turtleid;
#Basic(optional = false)
#Column(name = "TURTLE")
private String turtle;
#OneToMany(mappedBy = "turtleType") // or add cascade = javax.persistence.CascadeType.ALL and remove #Cascade if you are not using hibernate
#Cascade(value = CascadeType.ALL)
List<TurtleReview> turtleReviews;
...
}
#Entity
#Table(name = "TURTLE_REVIEW")
public class TurtleReview implements Serializable
{
#Column(name = "TURTLE_REVIEW_ID")
private int turtleReviewId;
#Column(name = "TURTLE_YEAR")
private int turtleYear;
#ManyToOne
#JoinColumn(name = "TURTLE_ID", referencedColumnName = "TURTLEID")
private TurtleLookup turtleType;
#Column(name = "IS_COMPLETE")
private short isComplete;
...
}
The scenario is the following
I have 2 tables, Company and Activity. A company can have one or more activities. One of these activities is a "primary" activity, and all others become secondary.
To handle this, I created 2 entities (Activity, Company) and a third entity for the join table, which is CompanyActivity
I used this tutorial as a starting point
Below my code (getters and setters omitted)
Company.java
#Entity
#Table(name = "T_COMPANY")
public class Company {
#Id
#Column(name = "COM_ID")
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "company")
private List<CompanyActivity> activities = new ArrayList<>();
}
Activity.java
#Entity
#Table(name = "T_ACTIVITY")
public class Activity {
#Id
#Column(name = "ACT_ID")
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String code;
private String description;
private boolean availableOnline;
}
CompanyActivity.java
#Entity
#Table(name = "T_COMPANY_ACTIVITY")
public class CompanyActivity {
#Id
#Column(name = "COM_ACT_ID")
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#ManyToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "COM_ID")
private Company company;
#ManyToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "ACT_ID")
private Activity activity;
private boolean primary;
}
Adding activities for a company works without a problem. The children collection contains the newly added activities, and there is always one marked as primary as expected.
The problem happens when updating a company.
When I add a new activity, all previous existing activities are persisted again.
When I remove an activity, it is not removed from the table.
I'm using this code to update a company' activities
company.getActivities().clear();
company.getActivities().addAll(newActivities);
company = repository.save(company);
In this code, newActivities have the new activities that should be considered (this collection does not have the previous ones, I just replace them all)
I tried adding orphanRemoval=true to the #OneToMany(cascade = CascadeType.ALL, mappedBy = "company") on Company, but this deletes the activity type when no other company is using it, which is wrong as they should be available always.
Can you please help me sync the activities collection on Company without removing elements from Activity table ?
Thanks a lot!
I solved it. Here are the steps I followed.
First, I changed my Join table entity cascade types as follows
#Entity
#Table(name = "T_COMPANY_ACTIVITY")
public class CompanyActivity {
#Id
#Column(name = "COM_ACT_ID")
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#ManyToOne(cascade = {CascadeType.PERSIST, CascadeType.MERGE})
#JoinColumn(name = "COM_ID")
private Company company;
#ManyToOne(cascade = {CascadeType.PERSIST, CascadeType.MERGE})
#JoinColumn(name = "ACT_ID")
private Activity activity;
private boolean primary;
}
Then, I added again the "orphanRemoval" property to Company mapping, and changed my CascadeTypes too, as follows
#OneToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE}, mappedBy = "empresa", orphanRemoval = true)
private List<CompanyActivity> activities = new ArrayList<>();
With these changes, my mapping works as expected with the same code I used to replace the relationships.
company.getActivities().clear();
company.getActivities().addAll(newActivities);
company = repository.save(company);
Thanks :)
The way you created your entities is not correct. You don't need to create an entity for your join table (CompanyActivity/T_COMPANY_ACTIVITY). Instead you should be using the #JoinTable on your activities entity. Something like below:
#OneToMany(cascade = CascadeType.ALL, mappedBy = "company")
#JoinTable(
name = "T_COMPANY_ACTIVITY",
joinColumns = #JoinColumn(name = "COM_ID"),
inverseJoinColumns = #JoinColumn(name = "ACT_ID")
)
private List<CompanyActivity> activities = new ArrayList<>();
for more detailed explanation on how One-to-Many/Many-to-One with Join tables work here: http://www.codejava.net/frameworks/hibernate/hibernate-one-to-many-association-on-join-table-annotations-example
I have two entities that used to be linked by a one to many relation but now they are linked by a many to many relation declared as follow :
SalesTeam entity :
#Entity
#Table(name = "SALES_TEAMS")
public class SalesTeam {
#Id
#Column(name = "ID")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#ManyToMany(fetch = FetchType.LAZY, cascade = {CascadeType.REFRESH, CascadeType.PERSIST})
#JoinTable(name = "WORKFLOW_FOR_SALESTEAM", inverseJoinColumns = {
#JoinColumn(name = "WFC_ID")
})
private List<WorkFlowCode> workFlowCodes = new ArrayList<>();
}
And the WorkFlowCode entity :
#Entity
#Table(name = "WORK_FLOW_CODE")
public class WorkFlowCode {
#Id
#Column(name = "ID")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#ManyToMany(fetch = FetchType.LAZY, cascade = {CascadeType.REFRESH, CascadeType.PERSIST})
#JoinTable(name = "WORKFLOW_FOR_SALESTEAM", inverseJoinColumns = {
#JoinColumn(name = "ST_ID")
})
private List<SalesTeam> salesteam = new ArrayList<>();
}
As I said the relation use to be one SalesTeam for several workflow codes but the requirement change and now it need to be a many to many relation. So I had a relation table and remove the former SALES_TEAM_ID column from the WORK_FLOW_CODE table. The problem is that now I always get an error when I try to get the WorkFlowCode from a SalesTeam. It appears that hibernate still adds the removed column to the query thus the relation had changed and nothing is left from the former relation description.
Here is the hibernate generated query :
select workflowco0_.SALES_TEAMS_ID as SALES_TE3_13_0_, workflowco0_.WFC_ID as WFC_ID4_16_0_, workflowco1_.ID as ID1_17_1_ from WORKFLOW_FOR_SALESTEAM workflowco0_ inner join WORK_FLOW_CODE workflowco1_ on workflowco0_.WFC_ID=workflowco1_.ID where workflowco0_.SALES_TEAMS_ID=?
As you can see the former SALES_TEAM_ID from WORK_FLOW_CODE table is still there.
How can I remove it ?
Thx
I have some problems with inheritance mapping. Here my database structure:
And associated entities:
AbstractEntity:
#MappedSuperclass
public abstract class AbstractEntity<ID extends Serializable> implements Serializable {
#Id #GeneratedValue(strategy = IDENTITY)
#Column(unique = true, updatable = false, nullable = false)
private ID id;
public ID getId() {
return id;
}
#SuppressWarnings("unused")
public void setId(ID id) {
this.id = id;
}
UserAcitvity entity:
#Entity #Table(name = "user_activity")
#Inheritance(strategy = JOINED)
#AttributeOverride(name = "id", column = #Column(name = "ua_id"))
public abstract class UserActivity extends AbstractEntity<Long> {
#ManyToOne(cascade = { MERGE, PERSIST }, fetch = LAZY)
#JoinColumn(name = "ua_user_id")
private User user;
...
}
Comment entity:
#Entity #Table(name = "comment")
#PrimaryKeyJoinColumn(name = "cm_id")
public class Comment extends UserActivity {
#ManyToOne(cascade = { MERGE, PERSIST }, fetch = LAZY)
#JoinColumn(name = "cm_question_id")
private Question question;
...
}
Question entity:
#Entity #Table(name = "question")
#PrimaryKeyJoinColumn(name = "qs_id")
public class Question extends UserActivity {
...
#OneToMany(fetch = LAZY, cascade = ALL, mappedBy = "question")
private List<Answer> answers = new ArrayList<>();
#OneToMany(fetch = LAZY, cascade = ALL, mappedBy = "question")
private List<Comment> comments = new ArrayList<>();
...
}
Answer entity:
#Entity #Table(name = "answer")
#PrimaryKeyJoinColumn(name = "asw_id")
public class Answer extends UserActivity {
#ManyToOne(cascade = { MERGE, PERSIST }, fetch = LAZY)
#JoinColumn(name = "asw_question_id")
private Question question;
...
}
and User entity:
#Entity #Table(name = "user")
#AttributeOverride(name = "id", column = #Column(name = "user_id"))
public class User extends AbstractEntity<Long> {
...
#OneToMany(cascade = REMOVE)
private List<Question> questions = new ArrayList<>();
#OneToMany(cascade = REMOVE)
private List<Answer> answers = new ArrayList<>();
#OneToMany(cascade = REMOVE)
private List<Comment> comments = new ArrayList<>();
...
}
Problem:
When I try to save or delete a User I get an exceptions:
org.springframework.dao.InvalidDataAccessResourceUsageException: could not prepare statement; SQL [insert into user_question (user_user_id, questions_qs_id) values (?, ?)]; nested exception is org.hibernate.exception.SQLGrammarException: could not prepare statement
and:
org.hibernate.engine.jdbc.spi.SqlExceptionHelper : 147 = user lacks privilege or object not found: USER_ANSWER
Hibernate is trying to create a table: user_question and user_answer which me do not need.
What I should doing for fixes ?
I don't think you can achieve this by mapping the ManyToOne association to User generically in the UserActivity entity. That's probably too confusing for the JPA provider (Hibernate).
Instead, I think you need to map the association to User in each of the Question, Answer and Comment entities. Yes, I know that would be duplicated code, but it looks like the only way you will then be able to qualify the OneToMany mappings in User using the mappedBy reference.
For instance, your Question entity would have an association defined as:
#ManyToOne(cascade = { MERGE, PERSIST }, fetch = LAZY)
#JoinColumn(name = "ua_user_id")
private User questionUser;
Depending on how clever (or not) Hibernate is about the above association, you may need to specify the table="USER_ACTIVITY" in the JoinColumn annotation.
Then the User would have the OneToMany as:
#OneToMany(mappedBy="questionUser", cascade = REMOVE)
private List<Question> questions = new ArrayList<>();
Similarly for each of Answer and Comment.
Of course, I haven't tried this, so I could be wrong.
It's probably happening because when you set the #OneToMany mapping then the hibernate will create an auxiliary table that will store the id from the entities on the relationship.
In this case you should try the following:
#OneToMany(cascade = REMOVE)
#JoinColumn(name = "answer_id")
private List<Answer> answers = new ArrayList<>();
The #JoinColumn annotation will map the relationship without the creation of the auxiliary table, so it's pretty likely this solution will help you in this situation.
Try this mapping, this should work as you expect according to section 2.2.5.3.1.1 of the documentation:
#Entity
public class User {
#OneToMany(cascade = REMOVE)
#JoinColumn(name="user_fk") //we need to duplicate the physical information
private List<Question> questions = new ArrayList<>();
...
}
#Entity
public class Question {
#ManyToOne
#JoinColumn(name="user_fk", insertable=false, updatable=false)
private User user;
...
}
The reason why the auxiliary association is created, is that there is no way for Hibernate to know that the Many side of the relation (for example Question) has a foreign key back to User that corresponds to the exact same relation as User.questions.
The association Question.user could be a completely different association, for example User.questionCreator or User.previousSuccessfulAnswerer.
Just by looking at Question.user, there is no way for Hibernate to know that it's the same association as User.questions.
So without the mappedBy indicating that the relation is the same, or #JoinColumn to indicate that there is no join table (but only a join column), Hibernate will trigger the generic one-to-many association mapping solution that consists in creating an auxiliary mapping table.
The schema misses such association tables, which causes the error that can be solved with the mapping above.
If you want unidirectional one-to-many usage in your entity relationship.
Try with..JoinTable
#OneToMany(cascade = REMOVE)
#JoinTable(name = "user_question", joinColumns = {
#JoinColumn(name = "user_id")}, inverseJoinColumns = {
#JoinColumn(name = "qs_id")})
private List<Question> questions = new ArrayList<>();