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Editorial Team
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Asked: 2026-05-30T10:30:44+00:00

I have one class named Question and another named StudentDriver . StudentDriver have a

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I have one class named Question and another named StudentDriver. StudentDriver have a list of questions. Since both classes are aggregate roots they have their own repository.

When I am going to add a new question, should the StudentDriver class have a method named addQuestion()? And would I merge the studentdriver object through the studentdriver repository, or would I persist the question with the question repository? If I persist it with question repository then the list of questions belonging to a studentdriver would not contain the newly added question until I refresh it from the database.

I don’t understand the connection between the two aggregate root objects and how I am going to model it correctly.

I am using JPA.

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1 Answer

  1. Editorial Team

    Looks like you have two options:

    1) Two aggregate roots. Adding new question would look like this:

    StudentDriver student = studentsRepository.findById(id);
Question question = someFactory.CreateForStudent(student);
questionsRepository.Persist(question);

    And getting all questions for a student will be a responsibility of the questions repository:

    IList<Question> studentQuestions = questionsRepository.findByStudent(student);

    Essentially you have a persistent unidirectional relationship from question to student: Question-belongs-to-StudentDriver (many-to-one).

    2) One aggregate root. StudentDriver is a root of the aggregate that contains list of questions. Adding new question would look like this:

    StudentDriver student = studentsRepository.findById(id);
student.addNewQuestion("Should you stop on a red light?", "Yes");
studentsRepository.Persist(student);

    To get all questions for a student you would use something like:

    IList<Question> studentQuestions = student.GetAllQuestions();

    The choice between two options depends on the information that is missing from the OP. Good way to identify aggregate root is to look at a lifecycle logic. Questions like

    • Can Question exist without corresponding Student?
    • Can Question be ‘reassigned’ from one Student to another?
    • When you delete/archive Student, should all Questions also be deleted?
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