In this article, we'll take a hands-on look at querying APIs using Kotlin and GraphQL. We'll walk through some of the basics of GraphQL and Kotlin, and then dive right into querying an API.
GraphQL is a query language for APIs. It was created by Facebook in 2012, and open-sourced in 2015. GraphQL provides a structured way to query data from an API. It also allows the API to evolve over time without breaking existing clients.
Kotlin is a statically-typed programming language that runs on the JVM. It was created by JetBrains in 2011, and open-sourced in 2012. Kotlin is a concise and readable language that is fully interoperable with Java.
To get started, we'll need to install the Kotlin compiler and the GraphQL library.
The Kotlin compiler is available for download from the Kotlin website. Simply download the latest version and unzip it to a directory of your choice.
The GraphQL library is available for download from the GraphQL website. Simply download the latest version and unzip it to a directory of your choice.
Now that we have the Kotlin compiler and the GraphQL library installed, we're ready to start querying an API.
To query an API, we first need to create a GraphQL query. A GraphQL query is a string that specifies the fields that you want to query. For example, the following query will fetch the id
, name
, and email
fields for a user:
query {
user {
id
name
email
}
}
We can then use the Kotlin compiler to compile the query and execute it against an API. The following example shows how to do this:
import com.graphql.client.GraphQL
fun main() {
val query = "query { user { id name email } }"
val result = GraphQL.execute(query)
println(result)
}
The execute
method will return a Result
object that contains the data that was returned by the API. In this case, the Result
object will contain the id
, name
, and email
fields for the user.
In this article, we took a hands-on look at querying APIs using Kotlin and GraphQL. We walked through some of the basics of GraphQL and Kotlin, and then dove right into querying an API.