GXT 3.0 JsonReader with multiple root objects - json

Question

I'm starting out with GXT and am a bit confused on how to use the JsonReader to parse a valid json string with multiple root objects. I have a set of selection boxes to build the sql statement to display records in a grid. I'm getting the values for the selections from the database as well. What I'm attempting to do is a single request to my php database functions to build the json with all the values for the selection boxes in one string. My first thought was the JsonReader.
Here's an example of the json I'm working with:
"categories":[{"id":"1","value":"categoryValue1"},{"id":"2","value":"categoryValue2"}], "frequencies":[{"id":"1","value":"frequencyValue1"},{"id":"2","value":"frequencyValue2"}]
Building off the cityList example in the api, this is what I've got so far.
JsonRootObject interface:
public interface JsonRootObject {
List<SelectionProperties> getCategories();
List<SelectionProperties> getFrequencies();
}
JsonRootObjectAutoBeanFactory:
public interface JsonRootObjectAutoBeanFactory extends AutoBeanFactory {
AutoBean<JsonRootObject> jsonRootObject();
}
I created a SelectionProperties interface as all are single int/string value pairs:
public interface SelectionProperties {
String getId();
String getValue();
}
Now, according to the api:
// To convert from JSON data, extend a JsonReader and override
// createReturnData to return the desired type.
So I created a reader for both categories and frequencies;
CategoryReader:
public class CategoryReader
extends
JsonReader<ListLoadResult<SelectionProperties>, JsonRootObject> {
public CategoriesReader(AutoBeanFactory factory, Class<JsonRootObject> rootBeanType) {
super(factory, rootBeanType);
}
protected ListLoadResult<SelectionProperties> createReturnData(Object loadConfig, JsonRootObject incomingData) {
return new ListLoadResultBean<SelectionProperties>(incomingData.getCategories());
}
}
FrequencyReader:
public class FrequencyReader extends
JsonReader<ListLoadResult<SelectionProperties>, net.apoplectic.testapps.client.JsonRootObject> {
public FrequencyReader(AutoBeanFactory factory, Class<JsonRootObject> rootBeanType) {
super(factory, rootBeanType);
}
protected ListLoadResult<SelectionProperties> createReturnData(Object loadConfig, JsonRootObject incomingData) {
return new ListLoadResultBean<SelectionProperties>(incomingData.getFrequencies());
}
}
This doesn't feel quite right. I'm creating multiple instances of basically the same code and parsing the actual json string twice (at this point. I may have more options for the grid once I dig in). My question is am I missing something or is there a more efficient way to parse the response string? From my onSuccessfulResponse:
JsonRootObjectAutoBeanFactory factory = GWT.create(JsonRootObjectAutoBeanFactory.class);
CategoryReader catReader = new CategoriesReader(factory, JsonRootObject.class);
FrequencyReader freqReader = new FrequenciesReader(factory, JsonRootObject.class);
categories = catReader.read(null, response);
frequencies = freqReader.read(null, response);
List<SelectionProperties> categoriesList = categories.getData();
List<SelectionProperties> frequenciesList = frequencies.getData();
ListBox cateBox = new ListBox(false);
ListBox freqBox = new ListBox(false);
for (SelectionProperties category : categoriesList )
{
cateBox.addItem(category.getValue(), category.getId());
}
for (SelectionProperties frequency : frequenciesList)
{
freqBox.addItem(frequency.getValue(), frequency.getId());
}
The above does work, both the ListBoxes are populated correctly. I just wonder if this is the correct approach. Thanks in advance!