Connecting to the Database

To store and retrieve cat data , we’ll need to connect to a database. We’ll use PostgreSQL for that purpose, although using another SQL database won’t be any different.

Adding the exposed library

First, we’ll need a new library to connect to the database. We’ll use the Exposed library, which is also developed by JetBrains.

Let’s add the following dependency to our build.gradle.kts file:

dependencies {
    implementation("org.jetbrains.exposed:exposed:0.17.14")
    implementation("org.postgresql:postgresql:42.2.24")
    ...
}

Connecting to the database

Once the libraries are in place, we need to connect to them. To do that, let’s create a new file called db.kt under /src/main/kotlin/catshostel with the following contents:

object DB {
     private val host=System.getenv("DB_HOST")?:"localhost"
     .
     .
     .
     fun connect() = Database.connect(
         "jdbc:postgresql://$host:$port/$dbName",
         driver =

...