a different object with the same identifier value was already associated with the session
hibernate, java, set
Solution
In the end i simply used merge() instead of save(), seems it solves the problem even though i have a set of objects and not just trying to work with a normal object.
Problem
Possible Duplicate: Hibernate: different object with the same identifier value was already associated with the session I get the following error: a different object with the same identifier value was already associated with the session I have two types of objects, Course and RecommendedSchedule which has a set of courses. Here are their xml definitions: ``` <hibernate-mapping> <class name="database.datatypes.Course" table="courses" lazy="false"> <id name="id" column="ID"> <generator class="assigned"/> </id> <property name="name" type="string"/> <property name="date"/> </class> ``` and ``` <hibernate-mapping> <class name="database.datatypes.RecommendedSchedule" table="recommended_schedules" lazy="false"> <id name="id" column="ID"> <generator class="increment"/> </id> <set name="courses" table="schedules_courses" cascade="save-update" lazy="false"> <key column="course_id"/> <many-to-many class="database.datatypes.Course"/> </set> <property name="semester" type="string"/> <property name="path" type="string"/> </class> ``` Basically if i insert two recommended systems with different sets, but using the same Course objects, it works, but if i do the exact same thing but use different Course objects (with the same values) i get the error. Anyone knows what I'm doing wrong? Here is an example for a piece of code that fails: ``` Session s = db.factory.openSession(); Set<Course> set1 = new HashSet<>(); Set<Course> set2 = new HashSet<>(); Course c1 = new Course(104167L, "Algebra A"); Course c2 = new Course(234114L, "Introduction to CS H and M"); Course c3 = new Course(104012L, "Calculus 1 T"); Course c4 = new Course(234145L, "Digital Systems"); Course c12 = new Course(104167L, "Algebra A"); Course c22 = new Course(234114L, "Introduction to CS H and M"); Course c32 = new Course(104012L, "Calculus 1 T"); Course c42 = new Course(234145L, "Digital Systems"); set1.add(c1); set1.add(c2); set1.add(c3); set2.add(c12); set2.add(c22); set2.add(c32); set2.add(c42); RecommendedSchedule r1 = new RecommendedSchedule(set1, "General 3 years", "1"); RecommendedSchedule r2 = new RecommendedSchedule(set2, "General 4 years", "1"); Collection<RecommendedSchedule> col = new ArrayList<RecommendedSchedule>(); Collection<Course> col2 = new ArrayList<Course>(); col.add(r1); col.add(r2); col2.add(c12); col2.add(c22); col2.add(c32); col2.add(c42); Transaction t = s.beginTransaction(); s.save(r1); s.save(r2); t.commit(); s.close(); ``` if i did instead: ``` set2.add(c1); set2.add(c2); set2.add(c3); set2.add(c4); ``` It would've worked. (This of course isn't the real issue, but a simple example)