1-issue-description.scala

/* I'm trying to refactor $and and $or (which are essentially the same code returning a different outer query).

The problem is that currently only "String, Any" pairs work, and I need to be able to combine both those *AND* "Query Expression Objects".

Here's the $or spec right now

*/ 
  "Casbah's DSL $or Operator" should {
    "Accept multiple values" in {
      val or = $or("foo" -> "bar", "x" -> "y")
      or must haveListEntry("$or", Seq(MongoDBObject("foo" -> "bar"), MongoDBObject("x" -> "y")))
    }
    "Work with nested operators" in {
      val or = $or( "foo" $lt 5 $gt 1, "x" $gte 10 $lte 152 )
      or must haveSuperclass[BasicBSONList]
      or must beEqualTo(MongoDBObject("$or" -> MongoDBList(MongoDBObject("foo" -> "bar", "x" -> "y"))))
    }
  }

/**
 the second block doesn't compile or work and I need to figure out an idiom that works.  

  I've fiddled with a few things but Type Classes don't work due to needing a wildcard / <: on the second arg to the tuple pairs.

*/

2-current-$or.scala

/**
 * Trait to provide the $or method as a bareword operator.
 *
 * $or ("Foo" -> "bar")
 *
 * Targets an RValue of (String, Any)* to be converted to a  DBObject  
 *
 * TODO - Test that rvalue ends up being an array e.g.:
 * 
 *   scala> $or ("foo" -> "bar", "X" -> 5)           
 *   res1: com.mongodb.casbah.commons.Imports.DBObject = { "$or" : [ { "foo" : "bar" , "X" : 5}]}
 *  
 * 
 * @author Brendan W. McAdams <brendan@10gen.com>
 * @since 2.0
 * @see http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-%24or
 */

trait OrOp extends BarewordQueryOperator {

  def $or(fields: (String, Any)*) = {
    val bldr = MongoDBList.newBuilder
    for ((k, v) <- fields) bldr += MongoDBObject(k -> v)
    MongoDBObject("$or" -> bldr.result)
  }

}

2-current-or.scala

/**
 * Trait to provide the $or method as a bareword operator.
 *
 * $or ("Foo" -> "bar")
 *
 * Targets an RValue of (String, Any)* to be converted to a  DBObject  
 *
 * TODO - Test that rvalue ends up being an array e.g.:
 * 
 *   scala> $or ("foo" -> "bar", "X" -> 5)           
 *   res1: com.mongodb.casbah.commons.Imports.DBObject = { "$or" : [ { "foo" : "bar" , "X" : 5}]}
 *  
 * 
 * @author Brendan W. McAdams <brendan@10gen.com>
 * @since 2.0
 * @see http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-%24or
 */

trait OrOp extends BarewordQueryOperator {

  def $or(fields: (String, Any)*) = {
    val bldr = MongoDBList.newBuilder
    for ((k, v) <- fields) bldr += MongoDBObject(k -> v)
    MongoDBObject("$or" -> bldr.result)
  }

}

3-type-class-tests.scala

trait OrOp extends BarewordQueryOperator {

  def $or(fields: (String, Any)*) = {
    val bldr = MongoDBList.newBuilder
    for ((k, v) <- fields) bldr += MongoDBObject(k -> v)
    MongoDBObject("$or" -> bldr.result)
  }

  def $or[A : ValidBarewordExpressionArgType](fields: A*) =
    MongoDBObject("$or" -> implicitly[ValidBarewordExpressionArgType[A]].listify(fields))
}

trait ValidTypes {
  trait KVPair[-A] extends ValidBarewordExpressionArgType[(String, A)] {
    def listify(args: Seq[(String, A)]): Seq[DBObject] = {
      val bldr = MongoDBList.newBuilder
      args.foreach(kv => bldr += MongoDBObject(kv))
      bldr.result.asInstanceOf[Seq[DBObject]]
    }
  }
  // Valid Bareword Query Expression entries
  trait CoreOperatorResultObj extends ValidBarewordExpressionArgType[DBObject with QueryExpressionObject] {
    def listify(args: Seq[DBObject with QueryExpressionObject]): Seq[DBObject] = {
      val bldr = MongoDBList.newBuilder
      args.foreach(bldr.+=)
      bldr.result.asInstanceOf[Seq[DBObject]]
    }
  }
}


trait ValidBarewordExpressionArgTypeHolder {
  import com.mongodb.casbah.query.ValidTypes.{CoreOperatorResultObj, KVPair}
  implicit def kvPairOk[A]: KVPair[A] = new KVPair[A] {}
  implicit object CoreOperatorResultObjOk extends CoreOperatorResultObj
}

// give it a shot!