I'm going to ask this question using a concrete example. An optimal answer would take into account that this is just an example for the general problem.

I'd like to implement a user management system with a Domain-Driven-Design approach.

• My system has users and groups.
• Group objects contain users.
• Group objects have a contains_user function.
• users and groups are part of the same bounded context.

Question

How would I implement the contains_user function in Domain-Driven-Design? How can I cleanly divide domain code / core and non-domain code / infrastructure?

My own thoughts

• Loading all users into the group might be bad performance-wise when there is a large number of users in a group.
• Performance-wise contains_user would best be implemented directly as DB query inside the function. But that would break DDD.

I'm going to ask this question using a concrete example. An optimal answer would take into account that this is just an example for the general problem.

I'd like to implement a user management system with a Clean Architecture approach.

• My system has users and groups.
• Group objects contain users.
• Group objects have a contains_user function.
• users and groups are part of the same bounded context.

Question

How would I implement the contains_user function in Clean Architecture? How can I cleanly divide domain code / core and non-domain code / infrastructure?

More abstract:

How can I separate an implementation detail (RDS) from domain code without loosing performance?

My own thoughts

• Loading all users into the group might be bad performance-wise when there is a large number of users in a group.
• Performance-wise contains_user would best be implemented directly as DB query inside the function. But that would break Clean Architecture.

I'm going to ask this question using a concrete example. An optimal answer would take into account that this is just an example for the general problem.

I'd like to implement a user management system with a Domain-Driven-Design approach.

• My system has users and groups.
• Group objects contain users.
• Group objects have a contains_user function.

Question

How would I implement the contains_user function in Domain-Driven-Design? How can I cleanly divide domain code and non-domain code?

My own thoughts

• Loading all users into the group might be bad performance-wise when there is a large number of users in a group.
• Performance-wise contains_user would best be implemented directly as DB query inside the function. But that would break DDD.

I'm going to ask this question using a concrete example. An optimal answer would take into account that this is just an example for the general problem.

I'd like to implement a user management system with a Domain-Driven-Design approach.

• My system has users and groups.
• Group objects contain users.
• Group objects have a contains_user function.
• users and groups are part of the same bounded context.

Question

How would I implement the contains_user function in Domain-Driven-Design? How can I cleanly divide domain code / core and non-domain code / infrastructure?

My own thoughts

• Loading all users into the group might be bad performance-wise when there is a large number of users in a group.
• Performance-wise contains_user would best be implemented directly as DB query inside the function. But that would break DDD.