AtkExpressionAttribute

Attribute: atkExpressionAttribute API docs | Flags

List of other attributes

File:AtkExpressionAttribute.png

atkExpressionAttribute screenshot

example:

$this->add(new atkExpressionAttribute("employee_count", "SELECT COUNT(*) 
                                                         FROM employee_department ed
                                                         WHERE ed.department_id = [table].id"));

This gives you a nice overview of the number of employees in each department in the admin overview of the department node.

Any SQL expression can be used and you can reference the node's table using the [table] block.

Similarly you can use join's (example below is for MySQL LEFT JOIN) to get information through relations. Example:

$this->add(new atkExpressionAttribute("widget_count", "SELECT COUNT(*) 
                                                         FROM widget wi 
                                                         LEFT JOIN widgetBatch wb ON wi.batch_ID=wb.batch_ID
                                                         WHERE wb.name_ID = [table].name_ID"));

Note: http://www.achievo.org/forum/viewtopic.php?t=2409&highlight=atkexpressionattribute