The QDataGrid Variables -- $_ITEM, $_COLUMN, $_CONTROL and $_FORM

As you may have noticed in the first example, we make use of the $_ITEM variable when we render each row's column. There are in fact three special variables used by the QDataGrid: $_ITEM, $_COLUMN, $_CONTROL and $_FORM.

$_ITEM represents a specific row's instance of the array of items you are iterating through. So in our example, the DataSource is an array of Person objects. Therefore, $_ITEM is the specific Person object for the row that we are rendering. $_COLUMN is the QDataGridColumn, $_CONTROL is the QDataGrid itself and $_FORM is the QForm itself.

So in our example, the first column shows the "Row Number", which is basically just the CurrentRowIndex property of the QDataGrid (e.g. $_CONTROL). And the last column's "Full Name" is rendered by the DisplayFullName method we have defined in our ExampleForm (e.g. $_FORM). Note that the DisplayFullName takes in a Person object. Subsequently, in our HTML defintion, we make the call to $_FORM->DisplayFullName passing in $_ITEM.

Finally, note that DisplayFullName is declared as a Public method. This is because DisplayFullName is actually called by the QDataGrid, which only has the rights to call Public methods in your ExampleForm class.