Parent Id null in @OneToMany mapping JPA

Question

I am using javax.persistence.OneToMany relationship in a Parent Child relationship. The parent Id is coming as null, I have read through all the related post in Stackoverflo

Answer 1

Usually empty FK columns are coming from setting only one side of the relation.

I imagine you have the following

DiversityTemplate diversityTemplate = ...
diversityTemplate.getAttributes().add(...)
...
diversityTemplateRepository.save(diversityTemplate);

This is wrong because the DiversityTemplateAttribute doesn't know about the parent, only the parent know about his children.

Solving this is easy, you have to set the parent reference in the child.

diversityTemplateAttribute.setDiversityTemplate(diversityTemplate);

Or you can put this logic into a method within the DiversityTemplate which automatically adds the attribute into the List + sets the backreference.