postData not passing any parameters!

You current implementation of serializeGridData just remove all functions parameters from the postData. So you should either extend data parameter inside of serializeGridData instead of the usage of postData. Another way is to modify serializeGridData to the following:

serializeGridData: function (data){
    var propertyName, propertyValue, dataToSend = {};
    for (propertyName in data) {
        if (data.hasOwnProperty(propertyName)) {
            propertyValue = data[propertyName];
            if ($.isFunction(propertyValue)) {
                dataToSend[propertyName] = propertyValue();
            } else {
                dataToSend[propertyName] = propertyValue
            }
        }
   }
   return JSON.stringify(dataToSend);
}

In the code above we enumerate all properties and call all functions explicitly. Moreover I prefer to use JSON.stringify function from json2.js. The function will be native implemented in many web browsers.

See the demo here.