Scala Cookbook

16.5. Searching a MongoDB Collection

Problem

You want to find objects in your MongoDB collection using Scala and the Casbah driver.

Solution

Use the find* methods of the MongoCollection class to get the elements you want, specifically the find and findOne methods.

Assuming that you have everything set up as shown in Recipe 16.3, the following code demonstrates these techniques:

• How to find all the documents in a collection

• How to find one document that matches your search criteria

• How to find all documents that match your search criteria

• How to limit the number of results returned by a find query

Here’s the code:

import com.mongodb.casbah.Imports._

object Find extends App {

  val collection = MongoFactory.collection

  // (1) find all stocks with find()
  // -------------------------------
  println("\n___ all stocks ___")
  var stocks = collection.find
  stocks.foreach(println)

  // (2) search for an individual stock
  // ----------------------------------
  println("\n___ .findOne(query) ___")
  val query = MongoDBObject("symbol" -> "GOOG")
  val result = collection.findOne(query)          // Some
  val stock = convertDbObjectToStock(result.get)  // convert it to a Stock
  println(stock)

  // (3) find all stocks that meet a search criteria
  // -----------------------------------------------
  println("\n___ price $gt 500 ___")
  stocks = collection.find("price" $gt 500)
  stocks.foreach(println)

  // (4) find all stocks that match a search pattern
  // -----------------------------------------------
  println("\n___ stocks that begin with ...