ensure that fields tagged with bson:"-" are never considered during querying

query.go

@@ -126,7 +126,7 @@ func populate(r Reference, rcoll string, rawDoc interface{}, d string, src inter
 			tag, err := structtag.Parse(string(ff.Tag))
 			if err == nil {
 				val, err2 := tag.Get("bson")
-				if err2 == nil {
+				if err2 == nil && val.Name != "-" {
 					fttt := ff.Type
 					if fttt.Kind() == reflect.Pointer || fttt.Kind() == reflect.Slice {
 						fttt = fttt.Elem()
@@ -175,6 +175,7 @@ func populate(r Reference, rcoll string, rawDoc interface{}, d string, src inter
 			src = t
 			toReturn = src
 		}
+		t.setExists(true)
 	}
 
 	if toReturn == nil {