Build a todo API

In this tutorial you build a small but complete API for a todo app, one step at a time. Each chapter adds one idea, and each one ends with an app that runs.

What you'll build

An HTTP API where you can:

• create, list, update, complete and delete tasks;
• group tasks into lists, and see the tasks of one list;
• protect every change with an API key;
• run tests against a real database;
• build a binary ready for production.

The chapters

	Chapter	What you learn
1	Create the project	prea new, prea dev, the project layout
2	Your first preá	generating a preá, its files and routes
3	The model	describing a table with a struct, migrations
4	Business rules	services, errors with a status, partial updates
5	A second preá	imports, exports and relations between tables
6	A middleware	components with settings and Init
7	Configuration	profiles for dev, tests and production
8	Testing	testing a preá and the whole app
9	Ship it	building, migrating and running in production

It takes about an hour. You can stop after any chapter and come back later.

Before you start

You need:

• Go 1.26 or newer and the prea CLI. See Installation.
• PostgreSQL, with two empty databases, todo and todo_test. A container works well:

docker run -d --name postgres -p 5432:5432 -e POSTGRES_PASSWORD=postgres postgres:17-alpine
docker exec postgres createdb -U postgres todo
docker exec postgres createdb -U postgres todo_test

• A way to send HTTP requests. The examples use curl, but any client works.

You don't need to know Preá. Some Go helps: structs, methods and errors.

The finished app

The code of the finished app lives in the Preá repository, in site/examples/todo. The CI builds and tests it on every change, so it always works with the current version.

Start with chapter 1 →