OlegIlyenko

In this gist I would like to describe an idea for GraphQL subscriptions. It was inspired by conversations about subscriptions in the GraphQL slack channel and different GH issues, like #89 and #411.

Conceptual Model

At the moment GraphQL allows 2 types of queries:

• query
• mutation

Reference implementation also adds the third type: subscription. It does not have any semantics yet, so here I would like to propose one possible semantics interpretation and the reasoning behind it.

OlegIlyenko

import sangria.ast
import sangria.execution.Executor
import sangria.marshalling.{InputUnmarshaller, ScalarValueInfo, ArrayMapBuilder, ResultMarshaller}
import sangria.schema._
import sangria.validation.{ValueCoercionViolation, IntCoercionViolation, BigIntCoercionViolation}
import spray.json._
import sangria.macros._
import scala.concurrent.ExecutionContext.Implicits.global

implicit object CustomSprayJsonResultMarshaller extends ResultMarshaller {

OlegIlyenko

import sangria.ast._
import sangria.execution._
import sangria.schema.Context
import sangria.marshalling.queryAst._

import java.util.concurrent.ConcurrentLinkedQueue

import scala.concurrent.duration.FiniteDuration
import scala.collection.JavaConverters._

OlegIlyenko

import io.Source
import scala.util.control.Breaks._

/**
 * Scala TicTacToe game without any side effects
 * 
 * Written in response to following post (which also contains task description):
 *   http://blog.tmorris.net/scala-exercise-with-types-and-abstraction/
 */
object TicTacToe {

OlegIlyenko

extend type Mutation {
  createDiscountCode(draft: DiscountCodeDraft!): DiscountCode
  
  updateDiscountCode(
    id: String!, 
    version: Long!, 
    actions: [DiscountCodeUpdateAction!]!): DiscountCode
  
  deleteDiscountCode(id: String!, version: Long!): DiscountCode
}

OlegIlyenko

input DiscountCodeUpdateAction {
  setName: SetDiscountCodeName
  setDescription: SetDiscountCodeDescription
  setCartPredicate: SetDiscountCodeCartPredicate
  setCustomType: SetDiscountCodeCustomType
  setCustomField: SetDiscountCodeCustomField
  
  # ...
}

OlegIlyenko

mutation UpdateDC {
  updateDiscountCode(
    id: "123"
    version: 5
    actions: [
      {setName: {name: {locale: "en", value: "10% off"}}}
      {changeIsActive: {isActive: false}}
    ]
  ) {
    id

OlegIlyenko

sealed abstract class DiscountCodeUpdateAction

case class SetDiscountCodeName(name: Option[LocalizedString]) 
  extends DiscountCodeUpdateAction

case class SetDiscountCodeDescription(description: Option[LocalizedString]) 
  extends DiscountCodeUpdateAction

case class SetDiscountCodeCartPredicate(cartPredicate: Option[String]) 
  extends DiscountCodeUpdateAction

OlegIlyenko

// Imports that you are using

import sangria.schema._
import sangria.execution._
import sangria.macros._
import sangria.marshalling.circe._
import scala.concurrent.ExecutionContext.Implicits.global

// The schema definition

OlegIlyenko

import sangria.schema._
import sangria.execution._
import sangria.macros._
import sangria.macros.derive._
import sangria.marshalling.circe._
import scala.concurrent.ExecutionContext.Implicits.global
import io.circe.generic.auto._

// Some basic data structures