domain-driven-design

问题 In a DDD -project I'm contributing to, we're seeking for some convenient solutions to map entity objects to domain objects and visa versa. Developers of this project agreed to fully decouple domain model from data model. The data layer uses JPA (Hibernate) as persistence technology. As we all reckon that persistence is an implementation detail in DDD, from a developers' point of view we're all seeking for the most appropriate solution in every aspect of the application. The biggest concern we

问题 In a DDD -project I'm contributing to, we're seeking for some convenient solutions to map entity objects to domain objects and visa versa. Developers of this project agreed to fully decouple domain model from data model. The data layer uses JPA (Hibernate) as persistence technology. As we all reckon that persistence is an implementation detail in DDD, from a developers' point of view we're all seeking for the most appropriate solution in every aspect of the application. The biggest concern we

问题 I'm learning DDD and the tutorial I'm currently following is implemented using NHibernate, but since my lack of experience with it I've decided to go through the course using EF Core 2.1. However, I'm currently a bit stuck with the following: I have three classes Customer which is an entity and two value objects ( CustomerStatus and inside of it value object ExpirationDate ) - like this: public class Customer : Entity { //... constructor, other properties and behavior omitted for the sake of

问题 Say I have two entities Notifications and Users. I want to mark that a user has seen a specific notification. This would commonly be done with a many-to-many relationship e.g. UserNotification Because there is no invariant around this relationship (we don't care if "all" users have seen the notification) these users shouldn't be on the notification aggregate. On the opposite side, the users aggregate doesn't need a list of notifications on it So that leads to say that the UserNotification

问题 or to create a domain layer that is consisted of domain models and talk to JPA entities for database accessing? What are the pros and cons for both approaches ? Thanks! 回答1: This does really depend on how you code your domain. In general (in Java) I prefer create a separate set of JPA annotated DTOs to work with persistence. Such DTOs will match db table and will be used within a custom repository that will expose to clients a semantic API will run queries against such DTOs will use factories

问题 or to create a domain layer that is consisted of domain models and talk to JPA entities for database accessing? What are the pros and cons for both approaches ? Thanks! 回答1: This does really depend on how you code your domain. In general (in Java) I prefer create a separate set of JPA annotated DTOs to work with persistence. Such DTOs will match db table and will be used within a custom repository that will expose to clients a semantic API will run queries against such DTOs will use factories

问题 I'm new to DDD and I'm stuck with many-to-many relationships. E.g. we have two aggregate roots - Tasks and Workers. Contract is definitely not aggregate root, because it has no sense without Task and Worker. So, it should be part of some aggregate. But which aggregate should it belong to? We need to know both summary costs of all task contracts and summary costs of all worker contracts. And it's natural for me to have contracts collection both in Task and in Worker. Well, I can move Costs

问题 I'm new to DDD and I'm stuck with many-to-many relationships. E.g. we have two aggregate roots - Tasks and Workers. Contract is definitely not aggregate root, because it has no sense without Task and Worker. So, it should be part of some aggregate. But which aggregate should it belong to? We need to know both summary costs of all task contracts and summary costs of all worker contracts. And it's natural for me to have contracts collection both in Task and in Worker. Well, I can move Costs

问题 I have been reading that Repositories should return domain objects only. I am having difficulty with implementing this. I currently have API with Service Layer, Repository and I am using EF Core to access sql database. If we consider User(Id, Name, address, PhoneNumber, Email, Username) and Orders (id, OrderDetails, UserId) as 2 domain objects. One Customer can have multiple Orders. I have created navigation property public virtual User User{ get; set; } and foreign Key. Service layer needs

问题 After reading lot of posts, I realised if an aggregate root exists for a concept/context, we need to have a single repository for that whole concept/context. If thats the case, I see there won't be any repositories for the internal entities. If so, how these internal entities are saved to database? I have a many internal entities under the aggregate root. So, wondering If I need to have all the saving of the internal entities under the aggregate root repository, it's going to be bloated.