CODEWITHSUNDEEP
javahibernatenullone-to-manymany-to-one
Alex Arvanitidis
Alex Arvanitidis

Reputation: 4464

Hibernate issue on creation OnetoMany,ManyToOne Mapping Giving null

I have a model like this:

@Entity
[...]
class ParentObject{
    [...]
    @OneToMany(cascade = CascadeType.ALL, mappedBy= "parentObject", orphanRemoval = true)
    private List<Relationship> relationship;
}

and in Relationship entity:

@ManyToOne
@JoinColumn(name="PARENT_OBJECT_ID")
private ParentObject parentObject;

and everything works fine on update and save. Only when I try to create a new ParentObject with new Relationships inside it:

parentObject: { 
  id: null, 
  relationship: [ 
      {id:null,
      parentObjectId:null,
      [...]
  }] 
}

hibernate doesn't have an id for the ParentObject, so Relationship.parentObject.id is null. Database throws an error saying:

cannot insert NULL into ("MYDB"."RELATIONSHIP"."PARENT_OBJECT_ID")

Any help would be appreciated.

Edit: Here's my service code:

public ParentObjectDto save(ParentObjectDto parentObjectDto) {
ParentObject parentObject = dtoConverter.convert(parentObjectDto, ParentObject.class);      

boolean isNewPO = parentObject.getId() == null ? true : false;

parentObject = parentObjectRepository.save(parentObject);

if (isNewPO) {
    // This loop ensures that when a new PO is added, the child relationship
    // objects are connected with the new parentObject that was just added.
    for (Relationship relationship : parentObject.getRelationship()) {
        relationship.setParentObject(parentObject);
    }
}

return dtoConverter.convert(parentObject, ParentObjectDto.class);

}

the names of course aren't the ones I write here, I just changed them to be more understandable, if I have any spelling mistakes it's from my manual changes :)

Upvotes: 1

Views: 687

Answers (1)

Predrag Maric
Predrag Maric

Reputation: 24433

Looking at the code, the problem might be when isNewPO is true you first save the PO and after that you set that parent object to the relationship. This means that at the time of persisting PO, relationships don't have their PO set, leading to NULL being inserted in PARENT_OBJECT_ID column (relationships are also persisted at this time because of cascade = CascadeType.ALL).

To resolve this, either move parentObject = parentObjectRepository.save(parentObject); after the loop, or wire up PO and its relationships in dtoConverter.convert().

Upvotes: 1

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