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POJPA Managed entities merge operations without cascade options
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  1. POJPA Managed entities merge operations without cascade options
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    copied!<p>i am trying to update an Entity inside a transaction, first i select the entity using its primary key, then lazily loaded its child entities and made changes to its properties through setter methods. After that when i merge the parent object, automatically all its child objects with OneToMany relations gets updated. Although this is the required functionality, but i am little confused with this behavior because i didn't specified any cascade options for the child entities. In order to make sure, i even tried a non-relational table, just queried using find JPAQL and changed its properties. When the transaction commited after the merge operation of the main entity, this non-relational entity also gets updated along with others. I am not sure this is the correct behavior, or its the problem of understanding the JPA and merge operation inside transactions.</p> <p>My Parent class</p> <pre><code>class Student @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Basic(optional = false) @Column(name = "id", nullable = false) private Integer id; private String name; @OneToMany(mappedBy = "student") private List&lt;Subjects&gt; subjects; public Integer getId(){ return id; } public void setId(Integer id){ this.id=id; } public String getName(){ return name; } public void setName(String name){ this.name=name; } </code></pre> <p>My Child class</p> <pre><code>Class Subjects @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Basic(optional = false) @Column(name = "id", nullable = false) private Integer id; @JoinColumn(name = "student", referencedColumnName = "id", nullable = false) @ManyToOne(optional = false) private Student student; public Integer getId(){ return id; } public void setId(Integer id){ this.id=id; } public String getCourse(){ return course; } public void setCourse(String course){ this.course=course; } </code></pre> <p>Non-Relational Entity is just an Entity class without any relations with this selected entity classes. I added it to just to check whether the updations happened due to any relations specified in the entity classes(Even without cascade options).</p> <p>My Transactional Update function.</p> <pre><code> Object obj1 = this.transactionTemplate.execute(new TransactionCallback() { public Object doInTransaction(TransactionStatus status) { Category category=findById('2'); //Non-Related entity with Student or Subject category.setName('new category'); Student student=findStudentById(1); for(Subjects subjects:student.getSubjects()){ subjects.setCourse("test"); } student.setName("student1"); entityManager.merge(student); return true; } }); </code></pre> <p>so the final outcome after merging and transaction commit is that, all the tables(Student, Subjects and Category)updated.</p>
 

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