I have the following data models:
Code:
Ext.regModel('Result', {
    associations: [
        {
            type: 'hasOne',
            model: 'Score',
            associationKey: 'halfTime',
            getterName: 'getHalfTime'
        },
        {
            type: 'hasOne',
            model: 'Score',
            associationKey: 'fullTime',
            getterName: 'getFullTime'
        },
        {
            type: 'hasOne',
            model: 'Score',
            associationKey: 'overTime',
            getterName: 'getOverTime',
            autoLoad: false
        },
        {
            type: 'hasOne',
            model: 'Score',
            associationKey: 'afterPenalties',
            getterName: 'getAfterPenalties',
            autoLoad: false
        }    
    ]
});

Ext.regModel('Score', {
    fields: [
        {name : 'home', type : 'int', optional: true, defaultValue: null}, 
        {name : 'away', type : 'int', optional: true, defaultValue: null}
    ],
    belongsTo: 'Result'
});
Now the problem is that some of the associations can be NULL in the received JSON data. Example:

Code:
"result":{
   "halfTime":{
      "home":3,
      "away":0
   },
   "fullTime":{
      "home":4,
      "away":1
   },
   "overTime":null,
   "afterPenalties":null
}
In this case if I try to access the data like

Code:
var score = result.getFullTime();
It results in the error:

Code:
Uncaught TypeError: Cannot call method 'indexOf' of undefined
If I remove the 'overTime' and 'afterPenalties' association it all works fine with the above data. I don't understand how I should add 'optional' associations.