Question

Lets suppose I have a basic CustomerEntity which has the following attributes

• Name
• Surname
• IsPreferred

Taking CQRS in it’s simplest form I would have the following services

• CustomerCommandService
• CustomerQueryService

If on the CustomerCommandService I call UpgradeToPreferred(CustomerEntity) The store behind it will update and any queries will reflect this. So far so good.

My question is how to I sync this back to the local entity I have? I have called the UpgradeToPreferred() method on the service not on the entity so it will not reflect in the local copy unless I query the CustomerQueryService and get the update which seems a tad redundant.

..Or am I doing it wrong?

EDIT:

To clarify, the question is. If I am going through a command service to modify the entity in storage and not calling the command on the entity directly or editing it’s properties how should I handle the same modification on the entity I have in memory.

Answer 1

Few things wrong here. Your comand service takes a command, not an entity. So if you want to upgrade that customer to be preferred, then the command would be the intent (makecustomerpreferred) and the data needed to perfomr the command (a customer identification would suffice). The service would load up the entity using the identification, and invoke the makepreferred behavior on the entity. The entity would be changed internally. Persistence would map it back to the database. Ergo, no need to resync with the database.