Examples
Kotlin GraphQL API
Building a GraphQL API
Kotlin GraphQL API with graphql-kotlin supports typed queries.
Introduction to GraphQL and Kotlin
GraphQL is a powerful query language for APIs, offering a more efficient and flexible alternative to REST. When combined with Kotlin, a modern and concise language, developers can create robust APIs that leverage the advantages of both technologies. In this guide, we'll explore how to implement a GraphQL API using the graphql-kotlin library, which supports typed queries, providing a seamless experience for Kotlin developers.
Setting Up Your Kotlin Project
Before we dive into writing GraphQL queries, we need to set up a Kotlin project with the necessary dependencies. We'll use Gradle as our build system. Add the following dependencies to your build.gradle.kts file:
Creating a Simple GraphQL Schema
GraphQL schemas define the structure of the queries you can make to your API. Let's create a simple schema to handle user data. The schema will include a User type and a query for fetching user details. First, create a Kotlin data class to represent a user:
Next, define the GraphQL schema in a .graphql file:
Implementing the GraphQL Resolver
Resolvers connect the schema to the backend data. We'll implement a simple resolver to fetch a user by their ID. In Kotlin, you create a resolver class and annotate the methods with @GraphQLQuery. Here's how:
Executing GraphQL Queries
With the setup complete, we can now execute GraphQL queries. Use a tool like GraphiQL or Postman to send a query to your server. Here's an example query to fetch a user by ID:
This query will return the name and email of the user with ID "1". By using the graphql-kotlin library, you can benefit from strong typing and Kotlin's expressive syntax, making the development of GraphQL APIs both enjoyable and efficient.
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