Hibernate saveorupdate is not updating

06-Aug-2017 16:48

An object persistence layer is said to implement persistence by reachability if any instance becomes persistent whenever the application creates an object reference to the instance from another instance that is already persistent.

This behavior is illustrated by the object diagram (note that this isn’t a class diagram) in figure 12.1. The objects Desktop PCs and Monitors are also persistent: They’re reachable from the Computer Category instance. Note that we assume navigation is possible only to child categories, but not to the parent—for example, you can call Child Categories().

You can’t even safely remove instances that aren’t referenced by any persistent object in memory; the instances in memory are only a small subset of all objects represented in the database.

Let’s look at Hibernate’s more flexible transitive persistence model.

Object-oriented data stores may implement a garbage-collection algorithm, similar to the one implemented for in-memory objects by the JVM.

For example, if you add a newly instantiated Category to the already persistent hierarchy of categories, it should become automatically persistent without a call to save() or persist().

“Mapping a parent/children relationship,” when you mapped a parent/child relationship between Bid and Item.

This topic shows you how to make data manipulations more efficient.

We optimize and reduce the amount of code that is necessary to store objects and discuss the most efficient processing options.

Object-oriented data stores may implement a garbage-collection algorithm, similar to the one implemented for in-memory objects by the JVM.For example, if you add a newly instantiated Category to the already persistent hierarchy of categories, it should become automatically persistent without a call to save() or persist().“Mapping a parent/children relationship,” when you mapped a parent/child relationship between Bid and Item.This topic shows you how to make data manipulations more efficient.We optimize and reduce the amount of code that is necessary to store objects and discuss the most efficient processing options.(SQL databases have a different approach to referential integrity, relying on declarative and procedural constraints to detect a misbehaving application.) In the purest form of persistence by reachability, the database has some top-level or root object, from which all persistent objects are reachable.