Mention how can you give objects an Unique Identity in DDD?
Câu trả lời
In Domain-Driven Design (DDD), giving objects a unique identity is crucial for distinguishing entities from one another, even if their attributes are identical. Here are several approaches to assigning unique identities to objects in DDD:
1. UUIDs/GUIDs
One common method is to use Universally Unique Identifiers (UUIDs) or Globally Unique Identifiers (GUIDs). These identifiers are generated in a way that ensures their uniqueness across different systems and contexts. This method is particularly useful in distributed systems where entities need to be uniquely identifiable across different databases and services[2][4][6].
2. Database-Generated IDs
Another approach is to rely on the database to generate unique identifiers. This can be done using auto-incrementing fields or sequences in relational databases. This method ensures that each entity gets a unique identifier upon creation, but it tightly couples the identity generation to the database layer, which might not align with DDD principles of keeping the domain model independent of the persistence mechanism[4][13].
3. Application Layer Generation
Unique identifiers can also be generated at the application layer. This approach decouples the identity generation from the database, allowing for more flexibility and control. For instance, identifiers can be generated using a combination of system clock, random numbers, or other deterministic methods. This method can be more complex to implement due to the need to handle potential collisions and ensure consistency[4][13].
4. Domain-Specific Identifiers
In some cases, the unique identity of an entity can be derived from domain-specific attributes. For example, a customer might be uniquely identified by a customer ID or a social security number. This approach ensures that the identifier is meaningful within the business context and can be easily understood by domain experts[7][15].
5. Composite Keys
For certain entities, a composite key made up of multiple attributes can serve as a unique identifier. This method is less common but can be useful in specific scenarios where the combination of attributes is guaranteed to be unique. However, it can complicate the domain model and persistence logic[12].
