To apply more than one guid the syntax is:
mx.data.action({
params : {
applyto : "selection"
actionname : "MyFirstModule.GetFavoriteFood",
guids : [281530811285515, 281530811285506],
},
callback : function(obj) {
// expect single MxObject
alert(obj.get("manufacturer"));
},
error : function(error) {
alert(error.description);
}
}, this);
You can see all of the documentation at http://apidocs.mendix.com/5/client/data.html