CascadeType.PERSIST not working when I am trying to save parent object - spring

Question

CascadeType.PERSIST not working when I am trying to save parent object (I am using spring data JPA)
Parent POJO
public class Course {
#Id
private Long courseId;
private String title;
private Integer credit;
#OneToOne
(cascade = CascadeType.PERSIST) // by this default joining column name will be
// course_material_course_material_id. you can give it more meaningful name
// using #JoinColumn
#JoinColumn(name = "fk_course_id", referencedColumnName = "courseMaterialId")
private CourseMaterial courseMaterial;
}
Child POJO
public class CourseMaterial {
#Id
private Long courseMaterialId;
private String url;
}
Controller Class Method
#PostMapping()
public void saveStudent(#RequestBody Course course) {
LOGGER.info("inside CourseController.saveStudent method");
courseService.saveCourse(course);
}
Sample request
{
"courseId":4,
"courseMaterial":{
"courseMaterialId":104,
"url":"www.java.com"
},
"credit":40,
"title":"learn java"
}
Error
javax.persistence.EntityNotFoundException: Unable to find com.sachin.demo.entity.CourseMaterial with id 104
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl$JpaEntityNotFoundDelegate.handleEntityNotFound(EntityManagerFactoryBuilderImpl.java:163) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:216) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:332) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.event.internal.DefaultLoadEventListener.doOnLoad(DefaultLoadEventListener.java:108) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:74) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:110) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.internal.SessionImpl.fireLoadNoChecks(SessionImpl.java:1186) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.internal.SessionImpl.internalLoad(SessionImpl.java:1051) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.type.EntityType.resolveIdentifier(EntityType.java:697) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.type.EntityType.resolve(EntityType.java:464) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.type.ManyToOneType.resolve(ManyToOneType.java:240) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.type.EntityType.resolve(EntityType.java:457) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.type.EntityType.replace(EntityType.java:358) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.type.AbstractType.replace(AbstractType.java:164) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.type.TypeHelper.replace(TypeHelper.java:204) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.event.internal.DefaultMergeEventListener.copyValues(DefaultMergeEventListener.java:488) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.event.internal.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:241) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:318) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:172) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:70) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:99) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:793) ~[hibernate-core-5.4.33.jar:5.4.33]
at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:780) ~[hibernate-core-5.4.33.jar:5.4.33]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:362) ~[spring-orm-5.3.14.jar:5.3.14]
at com.sun.proxy.$Proxy130.merge(Unknown Source) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64) ~[na:na]
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:311) ~[spring-orm-5.3.14.jar:5.3.14]
at com.sun.proxy.$Proxy130.merge(Unknown Source) ~[na:na]
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:600) ~[spring-data-jpa-2.5.7.jar:2.5.7]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64) ~[na:na]

Answer 1

Since you are updating an existing course, Spring Data JPA will use the EntityManager#merge method to make the course "managed", so only CascadeType#MERGE cascades are executed. If you want to create course material on-demand also in this case, you'll have to use #OneToOne(cascade = { CascadeType.PERSIST, CascadeType.MERGE}), or even #OneToOne(cascade = CascadeType.ALL) since the material seems to be "owned" by the course and shouldn't exist independently.