JsonIgnoreProperties [2017 Update]: You can now use JsonIgnoreProperties to suppress serialization of properties (during serialization), or ignore processing of JSON properties read (during deserialization). If this is not what you’re looking for, please keep reading below. (Thanks to As Zammel AlaaEddine for pointing this out). JsonManagedReference and JsonBackReference Since Jackson 1.6 you can use two … Read more
The annotation @JoinColumn indicates that this entity is the owner of the relationship (that is: the corresponding table has a column with a foreign key to the referenced table), whereas the attribute mappedBy indicates that the entity in this side is the inverse of the relationship, and the owner resides in the “other” entity. This … Read more
As you state JPA is just a specification, meaning there is no implementation. You can annotate your classes as much as you would like with JPA annotations, however without an implementation nothing will happen. Think of JPA as the guidelines that must be followed or an interface, while Hibernate’s JPA implementation is code that meets … Read more
Sometimes you have two entities and there’s a relationship between them. For example, you might have an entity called University and another entity called Student and a University might have many Students: The University entity might have some basic properties such as id, name, address, etc. as well as a collection property called students that … Read more
You should include cascade=”all” (if using xml) or cascade=CascadeType.ALL (if using annotations) on your collection mapping. This happens because you have a collection in your entity, and that collection has one or more items which are not present in the database. By specifying the above options you tell hibernate to save them to the database … Read more
Let’s say you have a collection of Car objects (database rows), and each Car has a collection of Wheel objects (also rows). In other words, Car → Wheel is a 1-to-many relationship. Now, let’s say you need to iterate through all the cars, and for each one, print out a list of the wheels. The … Read more