2023-03-08 21:39:52
Customer Aggregate
Customer
Aggregate Root
_a_m_p_;_darr; 1 .. n
Address
Address is part of the Customer.
Product Aggregate
Product
Aggregate Root
_a_m_p_;_darr; 1 .. n
Component
Component is part of the Product.
Every aggregate must have an
Aggregate
A transactional graph of objects.
Aggregate Root
The entry point of an aggregate ensures the integrity of the entire graph.
- Aggregate should enforce
data consistency within the aggregate. - Aggregate should ensure that it is
valid . - Data changes within an aggregate should follow ACID:
A tomicC onsistentI solatedD urable
Deleting the Root should delete the entire aggregate.
An aggregate is a cluster of associated objects that we treat as a unit for the purpose of data changes.
Eric Evans
Handling Relationships that Span Aggregates
External objects should interact with only the aggregate root .
Customer Aggregate
Customer
Aggregate Root
_a_m_p_;_darr; 1 .. n
Address
Address is part of the Customer.
_a_m_p_;_rlarr;
Product Aggregate
Product
Aggregate Root
_a_m_p_;_darr; 1 .. n
Component
Component is part of the Product.
- Aggregate root is responsible for maintaining the rules of the aggregate.
Aggregate Tips
Aggregates are not always the answer
Aggregates can connect only by the root
Don’t overlook using FKs for non-root entities
Too many FKs to non-root entities may suggest a problem
“Aggregates of one” are acceptable
“Rule of Cascading Deletes”
