How to find index of parent loop in itemTpl Sencha Touch

I have a table which has checkbox for each row. I am unable to select multiple checkboxes simantaneously. Below is the code of Item Tpl for ref:

+'<tpl for="rows">'
 + '<tr>'
   +'<tpl for="columns">'
     +'<tpl if="dataIndex== \'checkbox\'">'
        + '<td><input type="checkbox" id="checkbox{#}" class="regular-checkbox" /><label class="m0" for="checkbox{#}"></label></td>'
    +'<tpl else>'
      +'<td><p>{value}</p></td>'
    +'</tpl>'
  +'</tpl>'
 +'</tr>'
+'</tpl>'

I have a problem to get index for the rows loop in item Tpl to have a unique id for each checkbox. Can anyone guide me hoe to get it ?