Cash Flow API

A RESTful Web API built with C# and ASP.NET Core for managing expenses.

This project was developed primarily to understand how to manage database and entities using dependency injection extensions and also generating EXCEL and PDF reports, while also exploring concepts such as business rules, input validation, exception handling, and global exception filter.

Technologies

Features

• CRUD expenses
• Download Excel report by month
• Download PDF report by month
• Business rule validation
• Status and Priority validation
• Exception filter
• Swagger documentation (HTTP status code handling)

Layered Architecture

For this project, the following layered architecture was adopted:

1. CashFlow.API — The entry point of the application, responsible for handling HTTP requests through the controllers.
2. CashFlow.Application — The application/service layer, responsible for implementing the application's use cases and business rules.
3. CashFlow.Communication — The DTO layer, responsible for defining and organizing the request and response objects used to communicate between the API and the application layer.
4. CashFlow.Exception — The Exception layer, responsible for defining and organizing the aplication errors and saving the resourse message errors.
5. CashFlow.Infrastructure — The Infrastructure layer, responsible for defining and organizing the database communication.
6. CashFlow.Domain — The Domain layer, responsible for defining the entities and interfaces used in the Infrastructure layer.

API Endpoints

Method	Endpoint	Description
GET	/api/expenses	Get all expenses
GET	/api/expenses/{id}	Get a expense by ID
GET	/api/reports/excel?month=2026-09	Get expenses by the year-month and download the Excel report
GET	/api/reports/pdf?month=2026-09	Get expenses by the year-month and download the PDF report
POST	/api/expenses	Create a expense
PUT	/api/expenses/{id}	Update a expense
DELETE	/api/expenses/{id}	Delete a expense

What I Practiced

Through this project, I practiced:

• Layered architecture in .NET
• ASP.NET Core Web API
• RESTful API design
• HTTP methods and status codes
• Business rule implementation
• Exception handling
• Debugging with Visual Studio
• API documentation with Swagger
• Implement dependency injection
• How to use the MigraDoc to create and style a PDF report
• How to use the ClosedXML to create and style an Excel report

Next Steps

• Create the Migrations
• Implement unit tests
• Add authentication
• Add authorization for specific endpoints

How to run

Requirements

• Visual Studio version 2022+ or Visual Studio Code
• Windows 10+ or ​​Linux/MacOS with .NET SDK 8.0 or 9.0 installed
• PostgreSQL

Installation

1. Clone the repository:

git clone https://github.com/AnaLinsDev/cash-flow-api.git

2. Navigate to the project

cd cash-flow-api

3. Add your DB_PATH

Fill in the database information in the appsettings.Development.json file inside the CashFlow.API.

4. Restore dependencies

dotnet restore

5. Build the project

dotnet build

6. Creating database tables

// Here will be added the steps to run the migrations, but it will be added in the next steps

7. Run the API

dotnet run --project src/CashFlow.API

The terminal will display the URL where the API is running.

8. Open Swagger

Open the Swagger URL displayed by the application in your browser.

Swagger can be used to test the available API endpoints without requiring Postman or another API client.