Default values and records
This page is about defining default values and records in your model class, which only affects new records. You can set defaults directly in the database-schema, which affects existing records as well. See Data Types and Casting for details.
Static default values
The DataObject::$defaults array allows you to specify simple static values to be the default values when a record is created.
A simple example is if you have a dog and by default its bark is "Woof":
namespace App\Model;
use SilverStripe\ORM\DataObject;
class Dog extends DataObject
{
private static $db = [
'Bark' => 'Varchar(10)',
];
private static $defaults = [
'Bark' => 'Woof',
];
}Dynamic default values
In many situations default values need to be dynamically calculated. In order to do this, the DataObject::populateDefaults() method will need to be overridden.
This method is called whenever a new record is instantiated, and you must be sure to call the method on the parent object!
A simple example is to set a field to the current date and time:
namespace App\Model;
use SilverStripe\ORM\DataObject;
class Dog extends DataObject
{
// ...
/**
* Sets the Date field to the current date.
*/
public function populateDefaults()
{
$this->Date = date('Y-m-d');
parent::populateDefaults();
}
}This method is called very early in the process of instantiating a new record, before any relations are set for it. If you want to set values based on, for example, a has_one relation called Parent, you can do that by implementing onBeforeWrite() or a setter method - for example:
namespace App\Model;
use SilverStripe\ORM\DataObject;
class Dog extends DataObject
{
// ...
protected function onBeforeWrite()
{
// Only do this if the record hasn't been written to the database yet (optional)
if (!$this->isInDb()) {
$parent = $this->Parent();
// Set the FullTitle based on the parent, if one exists
if ($parent->exists()) {
$this->FullTitle = $parent->Title . ': ' . $this->Title;
} else {
$this->FullTitle = $this->Title;
}
}
}
// or
public function setFullTitle($value): static
{
$parent = $this->Parent();
// Set the FullTitle based on the parent, if one exists
if ($parent->exists()) {
$value = $parent->Title . ': ' . $value;
}
return $this->setField('FullTitle', $value);
}
}Static default records
The DataObject::$default_records array allows you to specify default records created when the database is built.
A simple example of this is having a region model and wanting a list of regions created when the site is built:
namespace App\Model;
use SilverStripe\ORM\DataObject;
class Region extends DataObject
{
private static $db = [
'Title' => 'Varchar(45)',
];
private static $default_records = [
['Title' => 'Auckland'],
['Title' => 'Coromandel'],
['Title' => 'Waikato'],
];
}Dynamic default records
Just like default values, there are times when you want your default records to have some dynamic value or to be created only under certain conditions. To achive this, override the DataObject::requireDefaultRecords() method.
use SilverStripe\Control\Director;
//...
public function requireDefaultRecords()
{
// Require the base defaults first - that way the records we create below won't interfere with any
// declared in $default_records
parent::requireDefaultRecords();
// Make some record only if we're in dev mode and we don't have any of the current class yet.
if (Director::isDev() && !DataObject::get_one(static::class)) {
$record = static::create(['Date' => date('Y-m-d')]);
$record->write();
}
}