[FIXED] Spring JPA - how to allow duplicate entries for @Id

Issue

I am querying a view which joins three tables and returns the result like below:

select * from v_project_details

Project_ID  Repo_Name Branch_Name
100         Repo1      Branch1
100         Repo1      Branch2
101         Repo2      Branch2

@Getter
@Setter
@Entity
@Table(name='v_project_details')
public class ProjectDetails{

@Id
@Column(name="Project_Id")
private int ProjectId
}

@Column(name="Repo_Name")
private String RepoName
}

@Column(name="Branch_Name")
private String BranchName
}

@Query(select p from v_project_details p)
List<ProjectDetails> findAll();

Results:

Project_ID  Repo_Name Branch_Name
100         Repo1      Branch1
100         Repo1      Branch1 - I am expecting Branch2 here
101         Repo2      Branch2

when i query the table from spring jpa, i see three results but first row is repeated twice.

Looks like hibernate is not reinstantiating the object if @Id value is repeated more than once in the result set.

How do i force it to reinstantiate the object ? I do not have an unique identifier in the view as my view is joined from different tables.

Solution

@Id is used by JPA to identify the primary key. In your case, project_id as your primary key, which JPA understands that both row1 and row2 as same records. If project_id is not your unique identifier for your records but instead a combination of multiple fields like (eg: combination of project_id, repo_name and branch_name), you need to define a composite primary key based on those 3 fields. refer to below post by baledung to know more on composite primary keys.

Composite primary keys with JPA

Answered By - mike