The VTEntityData object provides access to an entity object (a record in the application). It implements (among others) the following methods

getModuleName

Returns the module name of the entity.

getId

Returns id of the entity, this will return null if the id has not been saved yet.

getData

Returns the fields of the entity as an array where the field name is the key and the field's value is the value.

isNew

Returns true if new record is being created, false otherwise.

Example: Event handlers add/update distinction

    class MyModuleEventHandler extends VTEventHandler {
        function handleEvent($eventName, $data) {
            if ($data->isNew()) {
                // Creation of new record
            } else {
                // Editing existing record
            }
        }
    }

Modifying the fields of the entity object

In certain events, for example, 'vtiger.entity.beforesave.modifiable' it is possible to modify the entity, so that it gets saved. e.g, for an VTEntityData object called $data you can change the field simple_field to the value 'value' using the following code.

    $data->set('simple_field', 'value');

Now the entity will get saved with simple_field saved as 'value'.