Primary keys, IDs, references. The first attribute we add to our objects. They don't exist in the real world.

Problems

• Coupling

• Accidental Implementation

• Bijection Principle Violation.

Solutions

1. Reference object to objects.

2. Build a MAPPER.

3. Only use keys if you need to provide an external (accidental) reference. Databases, APIs, Serializations.

4. Use dark keys or GUIDs when possible.

5. If you are afraid of getting a big relation graph use proxies or lazy loading.

6. Don't use DTOs.

Code Smell 40 - DTOs

Maxi Contieri ・ Dec 2 '20

#oop #programming #tutorial #codenewbie

Sample Code

Wrong