Simply paid

Simple and secure payment service between people. Side project made to get hands dirty in back-end development with node and typescript.

📦 Technologies

• Node@20.0.9
• Typescript@5.3.3
• Vitest@1.2.1

How to run it

Using docker:

• Build the Docker Image: After creating the Dockerfile, you can build the Docker image using the following command:

docker build -t simply-paid .

This command tells Docker to build an image using the Dockerfile in the current directory and tag (-t) the image with the name "simply-paid".

• Run the Docker Container: Once the image has been built, you can run it as a container with the following command:

docker run -p 3000:3000 -d simply-paid

This command tells Docker to run a container from the "simply-paid" image, map port 3000 of the container to port 3000 of the host machine, and run the container in detached mode (-d).

💭 How it was built

First of all, after a slow and patient reading through the requirements, I got to understand what is the purpose of the project. Then I started some sketches to plan what I had to do and write some tests about the use cases.

📚 Learnings

Docker things

Dependency Inversion

Error handling with result pattern

The Result class in TypeScript is a design pattern used to handle operations that can either succeed or fail. It encapsulates the outcome of a computation along with its success status and any associated error message. The class uses generics, allowing it to work with different types of values.

Here's a breakdown of what the class does:

• Properties: The class has four properties: isSuccess, isFailure, error, and _value. isSuccess indicates whether the operation was successful, isFailure is the opposite of isSuccess, error contains any error message if the operation failed, and _value holds the actual value of the operation if it succeeded.

• Constructor: The constructor takes three parameters: isSuccess, error, and value. It checks for invalid states where a successful result has an error, or a failing result doesn't have an error. If such conditions are met, it throws an error.

• getValue: This method returns the value of the operation if it was successful. If the operation wasn't successful, it throws an error.

• ok: This static method creates a new Result instance representing a successful operation. It takes an optional value parameter.

• fail: This static method creates a new Result instance representing a failed operation. It requires an error parameter.

• combine: This static method takes an array of Result instances and returns the first failure it finds, or a successful result if there are no failures.

This class is a good way to handle operations that can either succeed or fail, providing a clear and consistent way to check the result of an operation and handle errors.

Data modeling relationships

Sources

• PicPay Desafio Back-End
• Why we need design patterns
• Refactoring Guru
• Types of software testing
• PHP static analysis tools
• Martin Fowler - Microservices
• REST Tutorial
• Vitest - Getting started
• How to Setup a TypeScript + Node.js Project
• The 5 commandments of clean error handling in TypeScript
• Handling errors like a pro in TypeScript
• Database table relationships
• Flexible Error Handling w/ the Result Class | Enterprise Node.js + TypeScript