extjs - How to make date picker readonly in sencha touch -

i have date picker in sencha touch . want make readonly.

can tell me how it. below code :

{             xtype: 'datepickerfield',             width: '100%',             labelwidth: '150px',             labelcls: 'labelfieldcss',             ui: 'text',             inputcls: 'selecttext',             dateformat: 'm d, y',             value: {                 day: new date().getdate(),                 month: (new date().getmonth() + 1),                 year: new date().getfullyear()             },             placeholder: 'select end date',             cls: 'customplaceholderfield',             id: 'expdate',             label: 'date'         } 

official docs can use readonly: true property http://docs.sencha.com/touch/2.2.1/#!/api/ext.field.datepicker-cfg-readonly