fix group with [] in inital SERVER-361

db/dbcommands.cpp

@@ -1278,7 +1278,7 @@ namespace mongo {
                 "  if ( $arr[n] == null ){ "
                 "    next = {}; "
                 "    Object.extend( next , $key ); "
-                "    Object.extend( next , $initial ); "
+                "    Object.extend( next , $initial , true ); "
                 "    $arr[n] = next; "
                 "    next = null; "
                 "  } "

jstests/group4.js

@@ -0,0 +1,45 @@
+
+t = db.group4
+t.drop();
+
+function test( c , n ){
+    var x = {};
+    c.forEach( 
+        function(z){
+            assert.eq( z.count , z.values.length , n + "\t" + tojson( z ) );
+        }
+    );
+}
+
+t.insert({name:'bob',foo:1})
+t.insert({name:'bob',foo:2})
+t.insert({name:'alice',foo:1})
+t.insert({name:'alice',foo:3})
+t.insert({name:'fred',foo:3})
+t.insert({name:'fred',foo:4})
+
+x = t.group( 
+    {
+        key: {foo:1},
+        initial: {count:0,values:[]},
+        reduce: function (obj, prev){
+            prev.count++
+            prev.values.push(obj.name)
+        }
+    } 
+);
+test( x , "A" );
+
+x = t.group(
+    {
+        key: {foo:1},
+        initial: {count:0},
+        reduce: function (obj, prev){
+            if (!prev.values) {prev.values = [];}
+            prev.count++;
+            prev.values.push(obj.name);
+        }
+    }
+);
+test( x , "B" );
+

shell/utils.js

@@ -125,9 +125,13 @@ assert.gt = function( a , b , msg ){
     doassert( a + " is not greater than " + b + " : " + msg );
 }
 
-Object.extend = function( dst , src ){
+Object.extend = function( dst , src , deep ){
     for ( var k in src ){
-        dst[k] = src[k];
+        var v = src[k];
+        if ( deep && typeof(v) == "object" ){
+            v = Object.extend( typeof ( v.length ) == "number" ? [] : {} , v , true );
+        }
+        dst[k] = v;
     }
     return dst;
 }