We-Eat/server/app/com/weEat/migrations/RecipeVersionCollection.scala

package com.weEat.migrations

import org.mongodb.scala.MongoDatabase
import com.mongodb.client.model._
import org.mongodb.scala.model.Filters._
import org.mongodb.scala.model.Field
import org.mongodb.scala.bson.{BsonArray,BsonDocument}
import com.weEat.shared.models.{FoodNodeId,RecipeNodeId}
import com.weEat.models.{FoodNodeView,FoodNode,RecipeVersion}
import scala.concurrent.ExecutionContext

object RecipeVersionCollection extends Migration {
  
  implicit val ec: ExecutionContext = ExecutionContext.global

  private def typ = `type` _

  def execute(db: MongoDatabase) = createRecipeVersionCollection(db)
    .flatMap((_) => createFoodView(db))

  def createRecipeVersionCollection(db: MongoDatabase) =
    db.createCollection(RecipeVersion.collectionName).head().flatMap({ (_) =>
      val foods = db.getCollection[RecipeNodeId](FoodNode.collectionName)
      foods.aggregate(Seq(
        Aggregates.`match`(equal("_t", "RecipeNodeId")),
        Aggregates.addFields(Field("vid", "$_id")),
        Aggregates.out(RecipeVersion.collectionName)
      )).head().flatMap({ (_) =>
        val foods = db.getCollection[FoodNodeId](FoodNode.collectionName)
        foods.aggregate(Seq(
          Aggregates.`match`(equal("_t", "RecipeNodeId")),
          Aggregates.project(Projections.fields(
            Projections.include("_id", "uid", "name"),
            Projections.computed("headVid", "$_id"),
            Projections.computed("_t", "RecipeMetaNodeId")
          )),
          Aggregates.merge(FoodNode.collectionName)
        ))
        .head()
      })
    })

  def createFoodView(db: MongoDatabase) =
    db.createView(
      FoodNodeView.collectionName,
      FoodNode.collectionName,
      Seq(
        Aggregates.lookup(
          RecipeVersion.collectionName,
          "headVid",
          "_id",
          "recipe"
        ),
        Aggregates.addFields(Field("recipe._id", "$_id")),
        Aggregates.replaceRoot(
          BsonDocument(("$ifNull", BsonArray(
            BsonDocument(("$first", "$recipe")),
            "$$ROOT"
          )))
        ),
        Aggregates.project(Projections.exclude("recipe")),
      )
    ).head()
}