Add and Remove
When an entity has a field that is a collection, we need to do a little extra work in addition to adding the basic get/set methods.
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The get method will return the whole collection.
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The set method will replace the whole collection.
We are going to create methods to add a single entity to a collection as well as remove one from a collection. * With a bi-directional relationship, your application code needs to account for both sides of the relationship. This ensures that the changes will be written to the database.
Note: In order for your add/remove/set method changes to be reflected in the database, the methods must be called inside of a transaction.
Drill¶
Modify your Language class by adding addFilm and removeFilm methods.
Practice Exercise¶
The addFilm and removeFilm methods are not necessary, but will make manipulating collections much easier.