I have made an aggregate class named Question. This contains references to Answer, Category, Feedback objects. Should the QuestionRepository be the class that contains all methods quering the database that relates to the Question but also all the methods for quering the Feedback, Answer etc? Or should these be seperate classes such as QuestionRepository, FeedbackRepository and so on.
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2 Answers
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From the way you have explained , I am assuming that each Question will have 1 or more Answers , 1 or more Feedback and the Question belongs to a particular Category
Since the Answer and Feedback are dependent on Question and cannot exist independently , you can have a single QuestionRepository for these 3 entities .
Coming to Category , category is more of a static entity which IMO is a static list , so all such static entities can be grouped together in a StaticRepository
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From the DDD web site :
For each type of object that needs global access, create an object that can provide the illusion of an in-memory collection of all objects of that type.
A repository is used when you need direct access to an entity, i.e. when there's no other convenient way to get hold of that entity than fetching it from a persistent store directly. In contrast, if you consider that the entity is most of the time easily obtainable through traversal of another object you've already got at hand, then there's no need for a repository. It seems to be the case with Answer, Category, and Feedback here.
Usually repositories are only for aggregate roots, though there may be exceptions.
I suggest you read the DDD blue book or some tutorial to get a basic comprehension of the DDD building blocks before you start building your domain model.
