5.4. Summary

In this chapter, we took a more in-depth look at various ways of mapping collections to the database. We looked at how the contents of the collection determine how it is mapped, and noted that there are many flexible options for storing different kinds of objects in various types of collections.

We showed that the difference between relationships and element collections was whether entities or basic/embeddable types were being stored in them. We went on to examine the different types of collections, and how Collection and Set can be used for simple container purposes, while List can be used to maintain ordered collections. We saw that there are two different approaches to using a List and that maintaining a persistent List is possible, but not usually the best strategy.