HowToGraphql - Sangria tutorial - Relations - finish

DAO.scala

package com.howtographql.scala.sangria
import DBSchema._
import com.howtographql.scala.sangria.models.{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
    )
}

DBSchema.scala

package com.howtographql.scala.sangria

import java.sql.Timestamp

import akka.http.scaladsl.model.DateTime
import com.howtographql.scala.sangria.models._
import slick.jdbc.H2Profile.api._

import scala.concurrent.duration._
import scala.concurrent.Await
import scala.language.postfixOps


object DBSchema {

  implicit val dateTimeColumnType = MappedColumnType.base[DateTime, Timestamp](
    dt => new Timestamp(dt.clicks),
    ts => DateTime(ts.getTime)
  )


  class LinksTable(tag: Tag) extends Table[Link](tag, "LINKS"){

    def id = column[Int]("ID", O.PrimaryKey, O.AutoInc)
    def url = column[String]("URL")
    def description = column[String]("DESCRIPTION")
    def postedBy = column[Int]("USER_ID")
    def createdAt = column[DateTime]("CREATED_AT")

    def * = (id, url, description, postedBy, createdAt).mapTo[Link]

    def postedByFK = foreignKey("postedBy_FK", postedBy, Users)(_.id)

  }

  val Links = TableQuery[LinksTable]

  class UsersTable(tag: Tag) extends Table[User](tag, "USERS"){
    def id = column[Int]("ID", O.PrimaryKey, O.AutoInc)
    def name = column[String]("NAME")
    def email = column[String]("EMAIL")
    def password = column[String]("PASSWORD")
    def createdAt = column[DateTime]("CREATED_AT")

    def * = (id, name, email, password, createdAt).mapTo[User]
  }

  val Users = TableQuery[UsersTable]

  class VotesTable(tag: Tag) extends Table[Vote](tag, "VOTES"){
    def id = column[Int]("ID", O.PrimaryKey, O.AutoInc)
    def userId = column[Int]("USER_ID")
    def linkId = column[Int]("LINK_ID")
    def createdAt = column[DateTime]("CREATED_AT")

    def * = (id, userId, linkId, createdAt).mapTo[Vote]

    def userFK = foreignKey("user_FK", userId, Users)(_.id)
    def linkFK = foreignKey("link_FK", linkId, Links)(_.id)
  }

  val Votes = TableQuery[VotesTable]

  /**
    * Load schema and populate sample data within this Sequence od DBActions
    */
  val databaseSetup = DBIO.seq(
    Users.schema.create,
    Links.schema.create,
    Votes.schema.create,

    Users forceInsertAll Seq(
      User(1, "mario", "mario@example.com", "s3cr3t"),
      User(2, "Fred", "fred@flinstones.com", "wilmalove")
    ),

    Links forceInsertAll Seq(
      Link(1, "http://howtographql.com", "Awesome community driven GraphQL tutorial",1, DateTime(2017,9,12)),
      Link(2, "http://graphql.org", "Official GraphQL web page",1, DateTime(2017,10,1)),
      Link(3, "https://facebook.github.io/graphql/", "GraphQL specification",2, DateTime(2017,10,2))
    ),

    Votes forceInsertAll Seq(
      Vote(1, 1, 1),
      Vote(2, 1, 2),
      Vote(3, 1, 3),
      Vote(4, 2, 2),
    )
  )



  def createDatabase: DAO = {
    val db = Database.forConfig("h2mem")

    Await.result(db.run(databaseSetup), 10 seconds)

    new DAO(db)

  }

}

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)))
  )


  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 SchemaDefinition = Schema(QueryType)
}

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


}