How do I add a variable to a form panel

[coletek]

Say I have a form with one field such as below, then how do I add a addition value to the form values, so its passed in the submit() call (as commented below):

Ext.define("test.view.AddCommentForm", {
    extend: 'Ext.form.Panel',
    xtype: 'addcommentform',


    requires: [
        'Ext.form.TextArea',
        'Ext.field.Hidden'
    ],


    config: {
        title: 'Add Comment',
        url: 'backend/add_comment.php',
        scrollable: false,


        items: [
            {
                xtype: 'fieldset',
                title: 'Add Comment',


                items: [
                    {
                        xtype: 'textareafield',
                        name: 'comment',
                        label: 'Comment',                                     
                        labelWidth: 150,
                        placeHolder: '',
                        required: true,
                        margin: 20,
                    }
                ]
            },
            {
                id: 'button-send',
                xtype: 'button',
                text: 'Send',
                ui: 'confirm',
                handler: function() {


                    var to_user_id = 50; // how do I add this to the form values, so they get passed in the submit call below, without having to add it to the item list above?


                    var values = this.up('addcommentform').getValues();


                    if (!values.comment)
                    {
                     	Ext.Msg.alert('Add Comment', 'Please enter your comment');
                    }
                    else if (!values.to_user_id) // clearly this will not work until the above variable to_user_id is added to the values
                    {
                     	Ext.Msg.alert('Add Comment', 'No user selected');
                    }
                    else
                    {
                     	this.up('addcommentform').submit({
                            success: function(form, result) {
				Ext.Msg.alert('Add Comment', 'Added comment successfully');
				form.reset();
                            },
                            failure: function(form, result) {
				Ext.Msg.alert('Add Comment', 'An error occurred, please try again later');
                            }
			});
                    }


		}


            }
	]


    }


});

[coletek]

Solved with following after "var to_user_id = 50;"

this.up('addcommentform').add({
                        xtype: 'hiddenfield',
                        name: 'user_id',
                        value: to_user_id
                    });