SAPUI5 - create a JSONModel from Ajax response - sapui5

Question

I'm trying to build a SAPUI5 application using JSON model.
I want to add 2 dropdown select menus, so that the second one fills in depending on the current selection of the first one.
I tried to get it done, but stucked at the very beginning.
This is what I get from Ajax (the object itself is passed from the server):
var data = {
"firm1":["firm1project1","firm1project2","firm1project3"],
"firm2":["firm2project1","firm2project2","firm2project3"],
"firm3":["firm3project1","firm3project2","firm3project3"],
"firm4":["firm4project1","firm4project2","firm4project3"]
};
var oModel = new sap.ui.model.json.JSONModel();
oModel.setData(data);
sap.ui.getCore().setModel(oModel);
The first menu should be the list of firms and the second one - is the selected firm's projects. And now I have no idea how to bind the data to the controls the right way.
Thank you.
EDIT:
According to what I've read in the developer's guide, the data that should appear in different controls is contained under fixed keys (as shown in "Aggregation Data Binding in a Simple Application" part of the page that I linked above), so it would be possible to just write something like:
var oListItemTemplate = new sap.ui.commons.ListItem("ListItemTemplate", {
text : "{firm}",
});
and for the projects:
var oListItemTemplate = new sap.ui.commons.ListItem("ListItemTemplate", {
text : "{firm/project}",
});
But in my case there is no firm key. My ListItems for the firm selection menu are keys, not values. And ListItems for the project selection menu are in an array, not just separate values under fixed keys.
So, is there a way or to bind somehow the data I have in its current form to controls, or how the data should look like to be useful for binding?

Answer 1

your data looks better like the following, the data binding JSON objects are with keys. And there are two data models needed for two dropdown boxes, multi data model binding should be used. I did a example at JSBin which fulfills your requirements, you can have a look and get some thoughts.
{
"firms": [
{
"name": "firm1",
"projects": [
{
"name": "firm1project1"
},
{
"name": "firm1project2"
},
{
"name": "firm1project3"
}
]
},
{
"name": "firm2",
"projects": [
{
"name": "firm2project1"
},
{
"name": "firm2project2"
},
{
"name": "firm2project3"
}
]
},
{
"name": "firm3",
"projects": [
{
"name": "firm3project1"
},
{
"name": "firm3project2"
},
{
"name": "firm3project3"
}
]
},
{
"name": "firm4",
"projects": [
{
"name": "firm4project1"
},
{
"name": "firm4project2"
},
{
"name": "firm4project3"
}
]
}
]
}