Question: I want to display a Column Chart which to show to quantity sold for list of items. Then I want to use the client events to track the click on item, I dont want o get the item name but the item_id. How can I do that?

Answer:: This is a workaround for this situation, you will create a special annotationText column under item name:

Let say your dataStore sample has three columns item_id item_name and quantity

<?php
ColumnChart::create([
    "dataStore"=>$this->dataStore("sample"),
    "columns"=>[
        "item_name"=>[
            "annotationText"=>function($row)
            {
                return (int)$row["item_id"];
            }
        ],
        "quantity"=>[
            "type"=>"number",
        ],
    ],
    "clientEvents"=>[
        "itemSelect"=>"function(params){
            console.log(params);
        }"
    ]
]);
?>

When user click to column, you can get the item_id in params.selectedRow[1]