General Info

• Objective: Development of an API in Nest.JS using the Factory Design Pattern. The boilerplate of this API was generated using Chat-GPT.

What are Design Patterns

From Refactoring Guru: Design patterns are typical solutions to commonly occurring problems in software design. They are like pre-made blueprints that you can customize to solve a recurring design problem in your code.

Creational design patterns provide various object creation mechanisms, which increase flexibility and reuse of existing code.

What is the Builder Design Pattern

From Refactoring Guru: Factory Method is a creational design pattern that provides an interface for creating objects in a superclass, but allows subclasses to alter the type of objects that will be created.

Pros:

• You avoid tight coupling between the creator and the concrete products.
• Single Responsibility Principle. You can move the product creation code into one place in the program, making the code easier to support.
• Open/Closed Principle. You can introduce new types of products into the program without breaking existing client code.

Cons:

• The code may become more complicated since you need to introduce a lot of new subclasses to implement the pattern. The best case scenario is when you’re introducing the pattern into an existing hierarchy of creator classes.

How this project was created

First, a new Nest.JS project was started through the CLI:

nest new factory-pattern-api

Then, a Boilerplate for this project was generated using Chat-GPT. The prompt given was: "Create a Nest.js api exemplifying the factory method design pattern". Chat-GPT indicated which entities, controllers and factories were needed for the project. The project required some adaptations to run properly.

References

• Refactoring Guru - Factory Pattern;
• ChatGPT;