RadioGroup not updating bound value

Question

I am using a radiogroup in my form, and I noticed that when I select one of the radio buttons, the value (bound value) is not updated.

Here's a small example:

Ext.create({
    xtype: 'container',
    renderTo: Ext.getBody(),
    items: [{
        xtype: 'formpanel',
        viewModel: {
            data: {
                myValue: 3
            }
        },
        items: [{
            xtype: 'displayfield',
            label: 'This is the value of myValue:',
            bind: '{myValue}'
        }, {
            xtype: 'textfield',
            label: 'Update myValue:',
            bind: '{myValue}'
        }, {
            xtype: 'radiogroup',
            vertical: true,
            label: 'Click a radio button:',
            bind: '{myValue}',
            items: [{
                label: 'One',
                value: 1
            }, {
                label: 'Two',
                value: 2
            }, {
                label: 'Three',
                value: 3
            }, ]
        }]
    }]
});

I created a simple viewModel with one data value: myValue: 3. This is bound to all of the form elements: the radiogroup, a textfield, and a displayfield.

I'd expect that when I click one of the radio buttons, that the displayfield would update its value. The displayfield value is updated when you type into the textfield, but the radiogroup is not updated.

It seems like the radiogroup is only using its bound value when it initializes, but it doesn't notice when it gets updated nor does it update it on its own.

What am I doing wrong? Why doesn't the bound value get updated when I click on a radio button?

Here's an example over on Sencha Fiddle: https://fiddle.sencha.com/#view/editor&fiddle/389i

---

UPDATE: I found a solution adding a change listener to the radiogroup. Well, this fixes updating myValue wen you click on a radio button. I'd need another listener to update the radiogroup when myValue is updated elsewhere (like in the textfield).

This works for my needs, but why should I need to add a change listener? Why doesn't the radiogroup bind to {myValue} correctly?

listeners: {
    change: function(field, val) {
        let vm = field.lookupViewModel();
        vm.set('myValue', val);
    }
}

Here's a fiddle with this update applied: https://fiddle.sencha.com/#view/editor&fiddle/389k

Answer 1

I ran into this issue earlier this year, but I don't think I ever reported it to Sencha because I was using the Community Edition. Anyway, from what I recall, I had tracked it down to some issue in the getValue method, believe it or not, and overrode that to the following (Fiddle here):

Ext.define('MyOverride', {
    override: 'Ext.field.RadioGroup',

    getValue: function () {
        var value = this.callParent(arguments);
        var bind = this.getBind()
        var bindValue = bind && bind.value;
        if (bindValue) {
            if (Ext.isEmpty(value) && !Ext.isEmpty(bindValue.getValue())) {
                value = bindValue.getValue()
            }
            bindValue.setValue(value)
        }
        return value
    }
});

I'm sure this isn't the right method for this override, but it unblocked me for the time being. Not sure if it's useful for you, but I wanted to share.