In Event Sourcing, How to make changes in database using arrays and no ORM?

Question

I have a class like this:

class Community{

    public List<Moderators> Moderators = new();
         public void AddModerator(Moderator moderator) => Moderators.Add(moderator)
    }

When i run the replay for all events from my EventStore, its ok to generate the list with moderators and send this to repository. But when the application call those events from API, i have a problem because i'm not using any ORM or Entity Framework cause my graph database doesn't have this. So if I have some change in moderator status or remove, or add an moderator, if i pass this to repository, i will need to check if moderator exists and then add, or if not in list, remove. How can i solve this in order to use domain entities? Maybe when call AddModerator from API I send some message to other service that add this moderator, for example? Or if I call DisableModerator(int moderatorId) someway i call another service to change this.

It's ok when I delete entire database and reconstruct replay all events, but in production I dont know how can i make these changes directly in moderator entity or repository when i change somethin in Moderators on Community aggregate root.

score 1 · Answer 1 · answered Sep 16 '22 at 05:27

To be able to handle updating the Database in a clean way, you need to create a Class outside of your DDD model that takes care of it. Inject your class into your Model and use it like you would use EntityFramework or any other ORM. For Example:

public class CommunityRepository {
    public CommunityRepository(IUoW Context) {
        _context = Context;
        ...
    }
    public void Save(Community community) {
        _context.save(community);
    }
}

This looks very similar to if you did you have an ORM implemented but you would own the class that implements IUoW interface. So, how do you write your own ORM? You can use a pattern called the Unit of Work Pattern. The Pattern is described in detail here - https://dotnettutorials.net/lesson/unit-of-work-csharp-mvc/

In Event Sourcing, How to make changes in database using arrays and no ORM?

1 Answers1