Setting default values on create and update in yii - yii2

Question

I am trying to update some fields in yii 1.1 using the following rules, but it is not working.
public function rules()
{
return [
['CreatedOn','default','value'=>time(),'isEmpty'=>true,'on'=>'insert'],
['CreatedBy','default','value'=>\Yii::$app->user->identity->id,'isEmpty'=>true,'on'=>'insert'],
['ModifiedOn','default','value'=>time(),'isEmpty'=>true,'on'=>'update'],
['ModifiedBy','default','value'=>\Yii::$app->user->identity->id,'isEmpty'=>true,'on'=>'update'],
];
}
I am looking to update CreatedBy and CreatedOn when inserting, and ModifiedBy and ModifiedOn when updating.

Answer 1

From soju's excellent answer, with Yii2:
By default, a model supports only a single scenario named default
You should therefore set the scenario manually in your controller i.e:
$model->scenario = 'insert';
You could also use when instead of on i.e:
['CreatedOn', 'default', 'value'=>time(), 'isEmpty'=>true, 'when'=>
function($model) { return $model->isNewRecord; }
],
['ModifiedOn', 'default', 'value'=>time(), 'isEmpty'=>true, 'when'=>
function($model) { return !$model->isNewRecord; }
],
An alternative to setting them in rules() would be to use beforeSave() to set them:
public function beforeSave($insert) {
if ($insert) {
$this->CreatedBy = \Yii::$app->user->identity->id;
$this->CreatedOn = time();
} else {
$this->ModifiedBy = \Yii::$app->user->identity->id;
$this->ModifiedOn = time();
}
return parent::beforeSave($insert);
}

Answer 2

This is the correct way to do it:
Behaviors:
public function behaviors()
{
return [
'timestamp' => [
'class' => TimestampBehavior::className(),
'attributes' => [
ActiveRecord::EVENT_BEFORE_INSERT => 'created_on',
ActiveRecord::EVENT_BEFORE_UPDATE => 'modified_on',
ActiveRecord::EVENT_BEFORE_DELETE => 'deleted_at',
],
'value' => function () {
return date('Y-m-d H:i:s');
}
],
[
'class' => BlameableBehavior::className(),
'createdByAttribute' => 'created_by_id',
'updatedByAttribute' => 'updated_by_id',
],
];
}
If you need just a simple rule for default value, this is enough:
public function rules()
{
return [
['CreatedOn','default','value'=>time()],
['ModifiedOn','default','value'=>time(),'isEmpty'=>true],
...
]
}
The 'isEmpty'=>true option override the default isEmpty() function and returns true (it is always seen as empty) dues it is always populated with time()

Answer 3

For Yii2 version 2.0.8 from April 2016 I had an error with 'isEmpty'=>true because according to documentation it expects a function so you must to do like this:'isEmpty' => function ($value) {return true;}.
When you use this solution you get a value for ModifiedBy even on create and I believe that was not an intention. It is possible to write isEmpty to return true in case of an update but I simply used 'when' because it is much more readable for me. So, my solution for rules in a model was :
['CreatedBy', 'default', 'value' => Yii::$app->user->id],
['ModifiedBy', 'default', 'value' => Yii::$app->user->id,
'when' => function ($model) { return !$model->isNewRecord;}],
As a side note for this question is that for timestamps you should rely on database to fill them, CreatedOn with default value and a before update trigger for ModifiedOn.