Question: I used Google Line Chart, however it shows error when there is no data available, how can I show a custom text in this case?

Answer: Very simple, you check the number of data row first before display chart

<?php
if($this->dataStore("mystore")->countData()>0)
{
    LineChart::create(array(
        "dataSource"=>$this->dataStore("mystore"),
        ...
    ));
}
?>