3 files changed, 65 insertions, 1 deletions
diff --git a/db/mr.cpp b/db/mr.cpp
index 79042b23d41..521ef79fcd2 100644
--- a/db/mr.cpp
+++ b/db/mr.cpp
@@ -124,6 +124,13 @@ namespace mongo {
                         finalizeCode = cmdObj["finalize"].ascode();
                     }
                     
+
+                    if ( cmdObj["mapparams"].type() == Array ){
+                        mapparams = cmdObj["mapparams"].embeddedObjectUserCheck();
+                    }
+                    else {
+                        mapparams = BSONObj();
+                    }
                 }
                 
                 { // query options
@@ -174,6 +181,8 @@ namespace mongo {
             string mapCode;
             string reduceCode;
             string finalizeCode;
+            
+            BSONObj mapparams;
 
             // output tables
             string incLong;
@@ -375,7 +384,7 @@ namespace mongo {
                         if ( mr.verbose ) mt.reset();
                         
                         state.scope->setThis( &o );
-                        if ( state.scope->invoke( state.map , BSONObj() , 0 , true ) )
+                        if ( state.scope->invoke( state.map , state.setup.mapparams , 0 , true ) )
                             throw UserException( (string)"map invoke failed: " + state.scope->getError() );
                         
                         if ( mr.verbose ) mapTime += mt.micros();
diff --git a/jstests/mr3.js b/jstests/mr3.js
new file mode 100644
index 00000000000..3ca5ef2b606
--- /dev/null
+++ b/jstests/mr3.js
@@ -0,0 +1,47 @@
+
+t = db.mr3;
+t.drop();
+
+t.save( { x : 1 , tags : [ "a" , "b" ] } );
+t.save( { x : 2 , tags : [ "b" , "c" ] } );
+t.save( { x : 3 , tags : [ "c" , "a" ] } );
+t.save( { x : 4 , tags : [ "b" , "c" ] } );
+
+m = function( n , x ){
+    x = x || 1;
+    this.tags.forEach(
+        function(z){
+            for ( var i=0; i<x; i++ )
+                emit( z , { count : n || 1 } );
+        }
+    );
+};
+
+r = function( key , values ){
+    var total = 0;
+    for ( var i=0; i<values.length; i++ ){
+        total += values[i].count;
+    }
+    return { count : total };
+};
+
+res = t.mapReduce( m , r );
+z = res.convertToSingleObject()
+
+assert.eq( 3 , z.keySet().length , "A1" );
+assert.eq( 2 , z.a.count , "A2" );
+assert.eq( 3 , z.b.count , "A3" );
+assert.eq( 3 , z.c.count , "A4" );
+
+res.drop();
+
+res = t.mapReduce( m , r , { mapparams : [ 2 , 2 ] } );
+z = res.convertToSingleObject()
+
+assert.eq( 3 , z.keySet().length , "B1" );
+assert.eq( 8 , z.a.count , "B2" );
+assert.eq( 12 , z.b.count , "B3" );
+assert.eq( 12 , z.c.count , "B4" );
+
+res.drop();
+
diff --git a/shell/collection.js b/shell/collection.js
index 50a24b1de5e..03eb824d1d0 100644
--- a/shell/collection.js
+++ b/shell/collection.js
@@ -502,6 +502,14 @@ MapReduceResult.prototype.drop = function(){
     return this._coll.drop();
 }
 
+/**
+* just for debugging really
+*/
+MapReduceResult.prototype.convertToSingleObject = function(){
+    var z = {};
+    this._coll.find().forEach( function(a){ z[a._id] = a.value; } );
+    return z;
+}
 
 /**
 * @param optional object of optional fields;