@ElementCollection VS @OneToMany in Hibernate
Published in
2 min readJul 31, 2020
What does this mean for you?
Well, first we are going to understand each concept one by one.
@ElementCollection
In the simplest term, @ElementCollection tells the compiler that we are mapping a collection, in which, @CollectionTable gives the name of the target table and then @JoinColumn specifies the actually column we join on like below:
It defines the relationship in following ways:
- One-To-Many relationship to an @Embeddable object
- One-To-Many relationship basic objects like Java primitives, wrapper, Date, String, etc.
@ OneToMany
It defines the One-To-Many relationship when the target objects are nothing but an entity only. As seen in the below example, one instructor can have multiple courses.
Comparison:
- @ElementCollection on the other hand, is very similar to @ OneToMany except target object is not an Entity.
- With @ElementCollection, we can’t query, persist or merge target object independently of their parent object.
- It doesn’t support cascade operation. It means target object are always persisted, merged, removed with their parent object.
- So, @ElementCollection is an easy way to define a collection with simple/basic objects. @ OneToMany is the best for complex use-case in which fine-grained control is required.
Hope you like it.
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