prestongarno/kotlinq

Kotlin DSL for GraphQL

a Kotlin GraphQL client for composable, reusable GraphQL queries

Query DSL (new with version 0.4.0)

Version 0.4.0 supports ad-hoc, type-hinted but natively expressed queries and mutations!

A powerful feature is the ability to compose and reuse graphql queries easily.

GraphQL Star Wars example

Define a "Human" type fragment:

    fun humanDef() = fragment("Human") {
      "name"(string)
      "nicknames" listOf !string
    }

Define a "Droid" type fragment:

    fun droidDef() = fragment("Droid") {
      "modelNumber"(string)
      "owner" on humanDef()
    }

Now, define a query for Star Wars characters:

    fun charactersQuery(fragments: List<Fragment>) = query {
      "characters"("first" to 10)..listOf {
        on..fragments
      }
    }

Query characters from Star Wars that are humans:

    val query = charactersQuery(listOf(humanDef())
    println(query.toGraphQl(pretty = true))

prints:

{
  characters(first: 100) {
    __typename
    ... on Human {
      name
      nicknames
    }
  }
}

But if you want to query both humans and droids, to do so it's as simple as:

    val query = charactersQuery(listOf(humanDef(), droidDef()))
    println(query.toGraphQl(pretty = true))

which results in:

{
  characters(first: 100) {
    __typename
    ... on Human {
      name
      nicknames
    }
    ... on Droid {
      modelNumber
      maker {
        name
        nicknames
      }
    }
  }
}