HowToGraphql - Sangria tutorial - Mutations

DAO.scala

package com.howtographql.scala.sangria
import DBSchema._
import com.howtographql.scala.sangria.models.{AuthProviderSignupData, Link, User, Vote}
import sangria.execution.deferred.{RelationIds, SimpleRelation}
import slick.jdbc.H2Profile.api._

import scala.concurrent.Future

class DAO(db: Database) {
  def allLinks = db.run(Links.result)

  def getLinks(ids: Seq[Int]): Future[Seq[Link]] = db.run(
    Links.filter(_.id inSet ids).result
  )

  def getLinksByUserIds(ids: Seq[Int]): Future[Seq[Link]] = {
    db.run {
      Links.filter(_.postedBy inSet ids).result
    }
  }

  def getUsers(ids: Seq[Int]): Future[Seq[User]] = db.run(
    Users.filter(_.id inSet ids).result
  )

  def getVotes(ids: Seq[Int]): Future[Seq[Vote]] = {
    db.run(
      Votes.filter(_.id inSet ids).result
    )
  }

  def getVotesByRelationIds(rel: RelationIds[Vote]): Future[Seq[Vote]] =
    db.run(
      Votes.filter { vote =>
        rel.rawIds.collect({
          case (SimpleRelation("byUser"), ids: Seq[Int]) => vote.userId inSet ids
          case (SimpleRelation("byLink"), ids: Seq[Int]) => vote.linkId inSet ids
        }).foldLeft(true: Rep[Boolean])(_ || _)

      } result
    )

  def createUser(name: String, authProvider: AuthProviderSignupData): Future[User] = {
    val newUser = User(0, name, authProvider.email.email, authProvider.email.password )

    val insertAndReturnUserQuery = (Users returning Users.map(_.id)) into {
      (user, id) => user.copy(id = id)
    }

    db.run {
      insertAndReturnUserQuery += newUser
    }
  }

  def createLink(url: String, description: String, postedBy: Int): Future[Link] = {

    val insertAndReturnLinkQuery = (Links returning Links.map(_.id)) into {
      (link, id) => link.copy(id = id)
    }
    db.run {
      insertAndReturnLinkQuery += Link(0, url, description, postedBy)
    }
  }

  def createVote(linkId: Int, userId: Int): Future[Vote] = {
    val insertAndReturnVoteQuery = (Votes returning Votes.map(_.id)) into {
      (vote, id) => vote.copy(id = id)
    }
    db.run {
      insertAndReturnVoteQuery += Vote(0, userId, linkId)
    }
  }
}

GraphQLSchema.scala

package com.howtographql.scala.sangria

import akka.http.scaladsl.model.DateTime
import sangria.schema.{ListType, ObjectType}
import models._
import sangria.ast.StringValue
import sangria.execution.deferred.{DeferredResolver, Fetcher, Relation, RelationIds}
import sangria.schema._
import sangria.macros.derive._

object GraphQLSchema {

  implicit val GraphQLDateTime = ScalarType[DateTime](//1
    "DateTime",//2
    coerceOutput = (dt, _) => dt.toString, //3
    coerceInput = { //4
      case StringValue(dt, _, _ ) => DateTime.fromIsoDateTimeString(dt).toRight(DateTimeCoerceViolation)
      case _ => Left(DateTimeCoerceViolation)
    },
    coerceUserInput = { //5
      case s: String => DateTime.fromIsoDateTimeString(s).toRight(DateTimeCoerceViolation)
      case _ => Left(DateTimeCoerceViolation)
    }
  )

  val IdentifiableType = InterfaceType(
    "Identifiable",
    fields[Unit, Identifiable](
      Field("id", IntType, resolve = _.value.id)
    )
  )

  lazy val LinkType: ObjectType[Unit, Link] = deriveObjectType[Unit, Link](
    Interfaces(IdentifiableType),
    ReplaceField("createdAt", Field("createdAt", GraphQLDateTime, resolve = _.value.createdAt)),
    ReplaceField("postedBy",
      Field("postedBy", UserType, resolve = c => usersFetcher.defer(c.value.postedBy))
    ),
    AddFields(
      Field("votes", ListType(VoteType), resolve = c => votesFetcher.deferRelSeq(voteByLinkRel, c.value.id))
    )
  )

  lazy val UserType: ObjectType[Unit, User] = deriveObjectType[Unit, User](
    Interfaces(IdentifiableType),
    AddFields(
      Field("links", ListType(LinkType),
        resolve = c =>  linksFetcher.deferRelSeq(linkByUserRel, c.value.id)),
      Field("votes", ListType(VoteType),
        resolve = c =>  votesFetcher.deferRelSeq(voteByUserRel, c.value.id))

    )
  )

  lazy val VoteType: ObjectType[Unit, Vote] = deriveObjectType[Unit, Vote](
    Interfaces(IdentifiableType),
    ExcludeFields("userId", "linkId"),
    AddFields(Field("user",  UserType, resolve = c => usersFetcher.defer(c.value.userId))),
    AddFields(Field("link",  LinkType, resolve = c => linksFetcher.defer(c.value.linkId)))
  )

  import sangria.marshalling.sprayJson._
  import spray.json.DefaultJsonProtocol._

  implicit val authProviderEmailFormat = jsonFormat2(AuthProviderEmail)
  implicit val authProviderSignupDataFormat = jsonFormat1(AuthProviderSignupData)

  implicit val AuthProviderEmailInputType: InputObjectType[AuthProviderEmail] = deriveInputObjectType[AuthProviderEmail](
    InputObjectTypeName("AUTH_PROVIDER_EMAIL")
  )

  lazy val AuthProviderSignupDataInputType: InputObjectType[AuthProviderSignupData] = deriveInputObjectType[AuthProviderSignupData]()

  val linkByUserRel = Relation[Link, Int]("byUser", l => Seq(l.postedBy))
  val voteByLinkRel = Relation[Vote, Int]("byLink", v => Seq(v.linkId))
  val voteByUserRel = Relation[Vote, Int]("byUser", v => Seq(v.userId))

  val linksFetcher = Fetcher.rel(
    (ctx: MyContext, ids: Seq[Int]) => ctx.dao.getLinks(ids),
    (ctx: MyContext, ids: RelationIds[Link]) => ctx.dao.getLinksByUserIds(ids(linkByUserRel))
  )

  val usersFetcher = Fetcher(
    (ctx: MyContext, ids: Seq[Int]) => ctx.dao.getUsers(ids)
  )

  val votesFetcher = Fetcher.rel(
    (ctx: MyContext, ids: Seq[Int]) => ctx.dao.getVotes(ids),
    (ctx: MyContext, ids: RelationIds[Vote]) => ctx.dao.getVotesByRelationIds(ids)
  )

  val Resolver = DeferredResolver.fetchers(linksFetcher, usersFetcher, votesFetcher)


  val Id = Argument("id", IntType)
  val Ids = Argument("ids", ListInputType(IntType))

  val QueryType = ObjectType(
    "Query",
    fields[MyContext, Unit](
      Field("allLinks", ListType(LinkType), resolve = c => c.ctx.dao.allLinks),
      Field("link",
        OptionType(LinkType),
        arguments = Id :: Nil,
        resolve = c => linksFetcher.deferOpt(c.arg(Id))
      ),
      Field("links",
        ListType(LinkType),
        arguments = Ids :: Nil,
        resolve = c => linksFetcher.deferSeq(c.arg(Ids))
      ),
      Field("users",
        ListType(UserType),
        arguments = List(Ids),
        resolve = c => usersFetcher.deferSeq(c.arg(Ids))
      ),
      Field("votes",
        ListType(VoteType),
        arguments = List(Ids),
        resolve = c => votesFetcher.deferSeq(c.arg(Ids))
      )
    )
  )

  val NameArg = Argument("name", StringType)
  val AuthProviderArg = Argument("authProvider", AuthProviderSignupDataInputType)
  val UrlArg = Argument("url", StringType)
  val DescArg = Argument("description", StringType)
  val PostedByArg = Argument("postedById", IntType)
  val LinkIdArg = Argument("linkId", IntType)
  val UserIdArg = Argument("userId", IntType)

  val Mutation = ObjectType(
    "Mutation",
    fields[MyContext, Unit](
      Field("createUser",
        UserType,
        arguments = NameArg :: AuthProviderArg :: Nil,
        resolve = c => c.ctx.dao.createUser(c.arg(NameArg), c.arg(AuthProviderArg))
      ),
      Field("createLink",
        LinkType,
        arguments = UrlArg :: DescArg :: PostedByArg :: Nil,
        resolve = c => c.ctx.dao.createLink(c.arg(UrlArg), c.arg(DescArg), c.arg(PostedByArg))),
      Field("createVote",
        VoteType,
        arguments = LinkIdArg :: UserIdArg :: Nil,
        resolve = c => c.ctx.dao.createVote(c.arg(LinkIdArg), c.arg(UserIdArg)))
    )
  )

  val SchemaDefinition = Schema(QueryType, Some(Mutation))
}

models_package.scala

package com.howtographql.scala.sangria

import akka.http.scaladsl.model.DateTime
import sangria.execution.deferred.HasId
import sangria.validation.Violation

package object models {

  trait Identifiable {
    val id: Int
  }

  object Identifiable {
    implicit def hasId[T <: Identifiable]: HasId[T, Int] = HasId(_.id)
  }

  case class Link(id: Int, url: String, description: String, postedBy: Int, createdAt: DateTime = DateTime.now) extends Identifiable

  case object DateTimeCoerceViolation extends Violation {
    override def errorMessage: String = "Error during parsing DateTime"
  }

  case class User(id: Int, name: String, email: String, password: String, createdAt: DateTime = DateTime.now) extends Identifiable

  case class Vote(id: Int, userId: Int, linkId: Int, createdAt: DateTime = DateTime.now) extends Identifiable

  case class AuthProviderEmail(email: String, password: String)

  case class AuthProviderSignupData(email: AuthProviderEmail)
}