Exposed

A real application has connected data. Users own notes. Notes have tags. Orders belong to customers. These connections are called relationships. In this tutorial, you will add relationships between tables, write JOIN queries, and build advanced filtering, sorting, and pagination. Types of Relationships Type Example Implementation One-to-Many One user has many notes Foreign key on notes table Many-to-Many Notes have many tags, tags belong to many notes Join table (note_tags) One-to-One One user has one profile Foreign key with unique constraint One-to-Many: Users → Notes A user can have many notes. Each note belongs to one user (or no user). ...

Our API works, but the data lives in memory. Restart the server and everything is gone. Time to add a real database. In this tutorial, you will connect your Ktor API to a database using Exposed — JetBrains’ SQL library for Kotlin. We will use H2 for development and explain how to switch to PostgreSQL for production. What is Exposed? Exposed is a SQL library made by JetBrains. It gives you two ways to work with databases: ...