EditableGrid how to fetch rows from MySql in php

I am trying to do an editable grid table in order to modify directly.
There is a field which I need to list all of it content so that I can select one.
Look at my code :

 function fetch_pairs($mysqli,$query){     if (!($res = $mysqli->query($query)))return FALSE;     $rows = array();     while ($row = $res->fetch_assoc()) {         $first = true;         $key = $value = null;         foreach ($row as $val) {             if ($first) { $key = $val; $first = false; }             else { $value = $val; break; }          }         $rows[$key] = $value;     }     return $rows; } $grid->addColumn('product-name', 'Product', 'string' , fetch_pairs($mysqli,'SELECT name FROM table_product'),true); 

In my database I have two tables:
-table_add{id,product-name} -table_product{id,name}
But the list is not appearing.
I am getting this error:
Could not load JSON from url ‘loaddata.php?db_tablename=table_add’
Any idea why ?

I don’t understand how and what you are doing. If you have an editable grid then why not just make a field of type select and put the query in there?