$expand multiple child entity sets on master item selection

Question

Hi,
I have OData service with following entityset structure:
Deals                       -> Master
   Systems               -> Detail
   Documents           -> Detail
   References           -> Detail
On Master view, I am displaying list of Deals. And when user selects any particular Deal from master view, it should show Systems, Documents and References list on details view.
Problem is its calling OData service 3 times, each for Systems, Documents and References. I want to fetch all these 3 details in one call.
I know we can use $expand. I have written following code in Master view for select event of List. And I notice its fetching data correctly here.
handleListSelect : function (evt) {
  //alert("context.getPath(): " + context.getPath());
  var context = evt.getParameter("listItem").getBindingContext();
  var oModel = this.getView().getModel();
  var newContext = null;
  oModel.read(context.getPath(), null, {"$expand":"SystemCollection,DocumentCollection,ReferenceCollection"}, false, function(oData, oResponse){ 
   var model = new sap.ui.model.json.JSONModel(oData);
   newContext = new sap.ui.model.Context(model, context.getPath());
  this.nav.to("Detail", newContext);
And in App.controller.js following code is written to set the context binding.
to : function (pageId, context) {
  var app = this.getView().app;
  // load page on demand
  var master = ("Master" === pageId);
  if (app.getPage(pageId, master) === null) {
   var page = sap.ui.view({
    id : pageId,
    viewName : "test.demo.view." + pageId,
    type : "XML"
   page.getController().nav = this;
   app.addPage(page, master);
   jQuery.sap.log.info("app controller > loaded page: " + pageId);
  // show the page
  app.to(pageId);
  // set data context on the page
  if (context) {
   var page = app.getPage(pageId);
   page.setBindingContext(context);     // Data is coming correctly here
And in Detail view item mapping is done:
<Table id="IbOverview" headerText="Systems"  items="{path : 'SystemCollection'}">
<List id="AttachmentList" items="{path : 'DocumentCollection'}"
<List items="{path : 'ReferenceCollection'}" headerText="Document References" >
I notice data is coming correctly in context but still Details view making individual calls for fetching Systems, Documents and Reference data. Am I missing something?
Regards,
Vikram

Answer 1

Hi,
          You link more than one Child table to a header table with document type, through code. It is highly possible.