Hibernate onetomany not updating

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Consider the following statements: Hibernate: select category0_. So far we have looked at the three different ways of deleting entities from the datastore using Hibernate APIs.

However, its drawback is that it doesn’t remove the associated instances, even an appropriate cascade type is specified in the class mappings/annotations. In this case, we have to write two queries: the first is to remove the products and the second is to remove the category.

At first this might look good but there is an issue with this implementation and that is that it includes the list of courses.

The course object might also include a list of students.

I knew that I was the only one modifying this row and the version had not changed.

After this I decided to implement an equals() and hash Code() for every single entity attached to the the object I was updating.

A transient instance is the one which does not associate with the session. However, this approach doesn’t remove associated instances.In above example, ‘merged Persistent Emp Entity’ is new entity which is persistent.So if you want to any more change, then make in in ‘merged Persistent Emp Entity’ instance.In this example professor_id will can be included in the business key for equality.Another potential issue that can happen is Lazy instantiation of entities.

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