Context and Problem Statement¶

Aggregate roots can be instansiated in a number of different ways.

Decision Drivers¶

• Must work well with EF Core
• Must be able to raise domain events on object creation
• Must keep aggregate roots in a valid state at all times

Considered Options¶

1. Factory Methods
2. Constructors
3. required init properties

Decision Outcome¶

Chosen option: "1. Factory Methods", because it is the only option that meets all the decision drivers.

Consequences¶

• private constructors can be used to ensure that aggregates are always in a valid state
• Need to use null! to remove nullable warnings

Pros and Cons of the Options¶

1. Factory Methods¶

• ✅ EF Core can still create the aggregate when hydrating data from the DB
• ✅ Domain events can be raised when aggregates are created via the application, but not when they are hydrated from the DB
• ✅ Provides a consistent way to create aggregates
• ✅ Aggregates remain encapsulated

2. Constructors¶

• ❌ EF will incorrectly raise domain events when hydrating data from the DB
• ❌ EF does not allow owned entities to be passed to constructors

3. required init properties¶

• ❌ Properties need to be passed to constructors to ensure they are in a valid state on object creation. Can't use required init properties as they then become unmodifiable