Play Framework Dependency Injection error

Question

This is my code:

package controllers

import javax.inject.Inject

import scala.concurrent.Future

import play.api.Logger
import play.api.mvc.{ Action, Controller }
import play.api.libs.concurrent.Execution.Implicits.defaultContext
import play.api.libs.functional.syntax._
import play.api.libs.json._

// Reactive Mongo imports
import reactivemongo.api.Cursor
import reactivemongo.api.ReadPreference

import play.modules.reactivemongo.{ // ReactiveMongo Play2 plugin
MongoController,
ReactiveMongoApi,
ReactiveMongoComponents

}

// BSON-JSON conversions/collection
import reactivemongo.play.json._
import play.modules.reactivemongo.json.collection._

/*
 * Example using ReactiveMongo + Play JSON library.
 *
 * There are two approaches demonstrated in this controller:
 * - using JsObjects directly
 * - using case classes that can be turned into JSON using Reads and Writes.
 *
 * This controller uses JsObjects directly.
 *
 * Instead of using the default Collection implementation (which interacts with
 * BSON structures + BSONReader/BSONWriter), we use a specialized
 * implementation that works with JsObject + Reads/Writes.
 *
 * Of course, you can still use the default Collection implementation
 * (BSONCollection.) See ReactiveMongo examples to learn how to use it.
 */
class Application @Inject() (val reactiveMongoApi: ReactiveMongoApi)
  extends Controller with MongoController with ReactiveMongoComponents  {

  def collection: Future[JSONCollection] =
   database.map(_.collection[JSONCollection]("Persons"))

  def index = Action { Ok("works") }

  def create(name: String, age: Int) = Action.async {
    val json = Json.obj(
      "name" -> name,
      "age" -> age,
      "created" -> new java.util.Date().getTime())

    collection.flatMap(_.insert(json)).map(lastError =>
      Ok("Mongo LastError: %s".format(lastError)))
  }
  }

I´ve an error that said can´t find database value (database is a member of ReactiveMongoApi Trait) so I guess there is something wrong with dependency injection. I added also this line to the build sbt:

adding routesGenerator := InjectedRoutesGenerator Any ideas? thank you!

score 1 · Answer 1 · answered Jul 24 '17 at 19:07

You need to refer to the injected API. That is, replace database with reactiveMongoApi.database:

class Application @Inject() (val reactiveMongoApi: ReactiveMongoApi)
  extends Controller with MongoController with ReactiveMongoComponents  {

  def collection: Future[JSONCollection] =
    reactiveMongoApi.database.map(_.collection[JSONCollection]("Persons"))
  ...
}

Play Framework Dependency Injection error

1 Answers1