如何在ExtJS中的绑定公式中使用逻辑运算符？

我在表单中有3个输入字段,并且只有在前两个输入具有值时才启用第三个输入.

这似乎不起作用:

Ext.define('MyApp.view.myobj.MyPanel', {
    extend:'Ext.Panel',

    viewModel: {},

    items: [{
        xtype: 'form',
        defaultType: 'textfield',
        items: [
            {fieldLabel: 'Field 1', reference: 'field1', publishes: 'value'},
            {fieldLabel: 'Field 2', reference: 'field2', publishes: 'value'},
            {
                fieldLabel: 'Field 3', 
                bind: {
                    disabled: '{!field1.value} || {!field2.value}'
                }
            },            
        ],
    }],
});

小提琴

在视图模型中,添加公式以返回{!field1.value} ||的值 {!field1.value}

按照小提琴:

viewModel: {
    formulas: {
        something: {
            bind: {
                x: '{!field1.value}',
                y: '{!field2.value}'
            },

            get: function (data) {
                if (data.x || data.y) return true;
                else return false;
            }
        }
    }
},

items: [{
    xtype: 'form',
    defaultType: 'textfield',
    bodyPadding: 10,
    items: [
        {fieldLabel: 'Field 1', reference: 'field1', publishes: 'value'},
        {fieldLabel: 'Field 2', reference: 'field2', publishes: 'value'},
        {
            fieldLabel: 'Field 3', 
            bind: {
                disabled: "{something}"
            }
        },            
    ],

}]