Scala Cookbook

16.6. Updating Documents in a MongoDB Collection

Problem

You want to update one or more documents in a MongoDB collection.

Solution

Use either the findAndModify or update methods from the Casbah MongoCollection class, as shown in this example:

import com.mongodb.casbah.Imports._
import Common._

object Update extends App {

  val collection = MongoFactory.collection

  // findAndModify
  // -------------

  // create a new Stock object
  val google = Stock("GOOG", 500)
  // search for an existing document with this symbol
  var query = MongoDBObject("symbol" -> "GOOG")
  // replace the old document with one based on the 'google' object
  val res1 = collection.findAndModify(query, buildMongoDbObject(google))
  println("findAndModify: " + res1)

  // update
  // ------

  // create a new Stock
  var apple = Stock("AAPL", 1000)
  // search for a document with this symbol
  query = MongoDBObject("symbol" -> "AAPL")
  // replace the old document with the 'apple' instance
  val res2 = collection.update(query, buildMongoDbObject(apple))
  println("update: " + res2)

}

In both cases, you build a document object to replace the existing document in the database, and then create a query object, which lets you find what you want to replace. Then you call either findAndModify or update to perform the update.

For instance, in the findAndModify example, a new Stock instance named google is created, and it’s used to replace the old document in the database whose symbol is GOOG. The buildMongoDbObject method is used to convert the google instance ...