🚀 How to Run

Requires Node.js 20.17.0 installed

git clone [email protected]:GiovanniPFilho/pokemon-api-consumer.git

cd pokemon-api-consumer

nvm use

npm install

node server.js

Visit: http://localhost:3000

Acess the route that you want see information:

/pokemon/name

Ex.: http://localhost:3000/pokemon/pikachu

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// THIS APPLICATION IS FOR STUDY AND LEARNING PURPOSES //

🧠 How to Think and Structure Scalable APIs in Node.js

🔹 1. Start with the problem: “What does this API need to do?”

In this case:

• Consume the PokéAPI
• Create custom endpoints (e.g., /pokemon/:name)
• Return filtered data in JSON

🧠 Thought process:
"I'm not going to save or modify anything. Just fetch external data and return it formatted."

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🔹 2. Use a layered architecture

This separation improves organization, testing, and maintainability.

Folder	Purpose
routes/	Defines API paths (e.g., GET /pokemon/:name)
controllers/	Handle requests and send responses
services/	Business logic (e.g., calling external APIs, formatting)
models/	Define the structure of the data being used
middlewares/	Handle validation, errors, authentication, etc.

• src/app.js: Builds the Express app with routes and middleware
• index.js: Entry point; initializes the app and starts the server

🧠 Thought process:
"Each layer has a specific responsibility. This helps keep code clean and scalable."

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🔹 3. Entry Point: index.js

It performs three main tasks:

• Loads .env variables using dotenv
• Imports the configured app from src/
• Starts the server and listens on a port

🧠 Thought process:
"index.js just boots the app. All app setup lives in src/."

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🔹 4. Application File: src/app.js

Here you:

• Create the Express instance
• Set the root route (/)
• Register custom routes (e.g., /pokemon)
• Add the error-handling middleware at the end

🧠 Thought process:
"app.js is the brain that puts all parts of the app together."

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🔹 5. Routing: routes/pokemon.routes.js

• Defines specific routes like GET /pokemon/:name
• Connects each route to its controller

🧠 Thought process:
"Each route knows who to call (the controller), but not how to handle it — that's the controller’s and service’s job."

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🔹 6. Controller: controllers/pokemon.controller.js

• Receives route parameters (e.g., :name)
• Calls the related service
• Sends the response to the client
• Uses try/catch to handle errors and forward them to the error middleware

🧠 Thought process:
"The controller is the bridge between the request and the business logic."

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🔹 7. Business Logic: services/pokemon.service.js

• Makes requests to the PokéAPI using fetch
• Throws an error if the request fails
• Filters and formats the response before returning it

🧠 Thought process:
"Heavy logic or external operations live in the services. The controller just calls and returns."

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🔹 8. Data Structure: models/pokemon.model.js

Even without a database, it’s useful to define the expected data structure.

🧠 Thought process:
"Models bring clarity and consistency, even without persistence."

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🔹 9. Error Handling: middlewares/errorHandler.middleware.js

• Catches errors thrown by controllers or services
• Logs them to the console
• Sends a 404 or a generic message to the client

🧠 Thought process:
"I don’t want try/catch everywhere. Centralized error handling is cleaner."

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🧠 How to Reason in Future Projects?

✅ Mental checklist:

1. What’s the API’s goal?
   e.g., fetch weather, create users, retrieve products

2. What are the endpoints?
   e.g., GET /weather/:city, POST /user

3. What does each route need to do?
   Call an external API? Save to a database? Validate input?

4. Organize into layers
   Route → Controller → Service → (optional: Model/DB)

5. Centralize error handling
   Use a final error middleware in app.js