Code Smell 50 - Object Keys
Maxi Contieri
Posted on December 12, 2020
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
Reference object to objects.
Build a MAPPER.
Only use keys if you need to provide an external (accidental) reference. Databases, APIs, Serializations.
Use dark keys or GUIDs when possible.
If you are afraid of getting a big relation graph use proxies or lazy loading.
Don't use DTOs.
Sample Code
Wrong
Right
Detection
This is a design policy.
We can enforce business objects to warn us if we define an attribute or function including the sequence id.
Tags
- Accidental
Conclusion
Ids are not necessary for OOP. You reference objects (essential) and never ids (accidental).
In case you need to provide a reference out of your system's scope (APIs, interfaces, Serializations) use dark and meaningless IDs (GUIDs).
Relations
Code Smell 20 - Premature Optimization
Maxi Contieri ・ Nov 8 '20
More info
The One and Only Software Design Principle
Maxi Contieri ・ Oct 13 '20
Credits
Photo by Maurice Williams on Unsplash
All problems in computer science can be solved by another level of indirection.
David Wheeler
Posted on December 12, 2020
Join Our Newsletter. No Spam, Only the good stuff.
Sign up to receive the latest update from our blog.