CODEWITHSUNDEEP
javahibernatejpapersistence
Kristoffer Tølbøll
Kristoffer Tølbøll

Reputation: 3327

Setting id of OneToMany relationship when persisting entity

I have a hibernate application, where I want to persist an owner.

One owner can have many animals

(inside Owner entity)

   @OneToMany(mappedBy = "owner")
private List<Animal> animals;

(inside Animal entity)

  @ManyToOne
private Owner owner;

I have a repository, where I persist my owner, 

   @Override
public Owner create(String name, String email, int age, 
List<Animal> animals) {
    Owner owner = new Owner(name, email, age, animals);
    for(Animal animal: animals){
        animal.setOwner(owner);
    }
    getEntityManager().persist(owner);
    return owner;
}
}

the owner is persisted correctly, but the foreign key is not set in the animal table.

I used the debugger to check that the owner is set correctly for the animal which it is.

First, I tried persisting the animal which caused an error

   for(Animal animal: animals){
        animal.setOwner(owner);
        getEntityManager().persist(animal)
    } //caused an error

so I thought about using a type of cascade, to make sure, the animal gets the Owner id into the database, 

@OneToMany(cascade = CascadeType.ALL)
private List<Animal> animals;

this caused an error as well

 "cause": {
  "detailMessage": "detached entity passed to persist: com.tolboll.zoo.data.entities.Animal",
  "stackTrace": [],
  "suppressedExceptions": []
},

how can i make it so, that the owner is correctly persisted into the animal entity?

EDIT:

here is the JSON body passed in

  {
    "name": "kristoffer",
    "email": "[email protected]",
    "age": 23,
    "animals": [{
        "id": 1,
        "name": "Simba",
        "weight": 110,
        "species": {
            "id": 1,
            "name": "Lion"
        }
    }]
}

Upvotes: 1

Views: 68

Answers (1)

user10871691
user10871691

Reputation:

You get that error because you are trying to persist a detached entity: Animal.

Solution

In the Owner entity, leave as it is (although CascadeType.MERGE is enough):

@OneToMany(cascade = CascadeType.ALL)
private List<Animal> animals;

Then, in the create method, replace persist by merge:

getEntityManager().merge(owner);

The reason for that is the merge operation that you need for the animals list.

Upvotes: 1

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