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このクラスからオブジェクトをインスタンス化するにはどうすればよいですか? MongoUtils以下に定義されているクラスを使用したい別のクラスがあります。このクラスはreactmongoからのものです

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

  /*
   * Get a JSONCollection (a Collection implementation that is designed to work
   * with JsObject, Reads and Writes.)
   * Note that the `collection` is not a `val`, but a `def`. We do _not_ store
   * the collection reference to avoid potential problems in development with
   * Play hot-reloading.
   */
  def collection: JSONCollection = db.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.insert(json).map(lastError =>
      Ok("Mongo LastError: %s".format(lastError)))
  }

  def createFromJson = Action.async(parse.json) { request =>
    import play.api.libs.json.Reads._
    /*
     * request.body is a JsValue.
     * There is an implicit Writes that turns this JsValue as a JsObject,
     * so you can call insert() with this JsValue.
     * (insert() takes a JsObject as parameter, or anything that can be
     * turned into a JsObject using a Writes.)
     */
    val transformer: Reads[JsObject] =
      Reads.jsPickBranch[JsString](__ \ "firstName") and
        Reads.jsPickBranch[JsString](__ \ "lastName") and
        Reads.jsPickBranch[JsNumber](__ \ "age") reduce

    request.body.transform(transformer).map { result =>
      collection.insert(result).map { lastError =>
        Logger.debug(s"Successfully inserted with LastError: $lastError")
        Created
      }
    }.getOrElse(Future.successful(BadRequest("invalid json")))
  }

  def findByName(name: String) = Action.async {
    // let's do our query
    val cursor: Cursor[JsObject] = collection.
      // find all people with name `name`
      find(Json.obj("name" -> name)).
      // sort them by creation date
      sort(Json.obj("created" -> -1)).
      // perform the query and get a cursor of JsObject
      cursor[JsObject]()

    // gather all the JsObjects in a list
    val futurePersonsList: Future[List[JsObject]] = cursor.collect[List]()

    // transform the list into a JsArray
    val futurePersonsJsonArray: Future[JsArray] =
      futurePersonsList.map { persons => Json.arr(persons) }

    // everything's ok! Let's reply with the array
    futurePersonsJsonArray.map { persons =>
      Ok(persons)
    }
  }
}

これまで試してみval mongoutil = new MongoUtils(reactiveMongoApi = play.modules.reactivemongo) ましたが、どうやらうまくいかないようです。

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2 に答える 2

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Play の依存性注入メカニズムを使用して、MongoDB へのインターフェースである ReactiveMongoApi のインスタンスを解決できます。手順は次のとおりです。

以下の行を application.conf に追加します

play.modules.enabled += "play.modules.reactivemongo.ReactiveMongoModule"
play.modules.enabled += "modules.CommonModule"

modules.CommonModuleはバインディングを定義する場所です。これにより、Play 2.4 に統合された DI フレームワークである Guice は、特定のインターフェイスに使用する実装を認識できます。例えば、

package modules

import com.google.inject.AbstractModule
import dao.impl.UserDaoMongo
import dao.UserDao
import play.api.{Configuration, Environment}
import services.{UserService, UserServiceImpl}
case class CommonModule(environment: Environment, configuration: Configuration) extends AbstractModule {

  def configure() {
    bindDAOs()
    bindServices()
  }

  private def bindDAOs(): Unit = {
    bind(classOf[UserDao]).to(classOf[UserDaoMongo])
  }

  def bindServices(): Unit = {
    bind(classOf[UserService]).to(classOf[UserServiceImpl])
  }
}

さらに、コントローラーをシングルトンにすることをお勧めします。例えば：

import javax.inject.{Singleton, Inject}

@Singleton    
class UserController @Inject()(userService: UserService) extends Controller {

Play フレームワークで Reactivemongo を使用する方法については、こちらをお読みください。一方、これは完全な例です: https://github.com/luongbalinh/play-mongo

于 2016-01-19T06:44:22.077 に答える