Add new attribute dynamically to the existing model object in Yii2 framework - yii2

Question

In Yii2 framework is it possible to add a new attribute dynamically to an existing object, which is retrieved from Database?
Example
//Retrieve from $result
$result = Result::findone(1);
//Add dynamic attribute to the object say 'result'
$result->attributes = array('attempt' => 1);
If it is not possible, please suggest an alternate best method to implement it.
Finally I would be converting the result to a json object. In my application, at the behaviour code block, I have used like this:
'formats' => [
'application/json' => Response::FORMAT_JSON,
],

Answer 1

You can add define a public variable inside your model, that will store dynamic attributes as associative array. It'll look something like this:
class Result extends \yii\db\ActiveRecord implements Arrayable
{
public $dynamic;
// Implementation of Arrayable fields() method, for JSON
public function fields()
{
return [
'id' => 'id',
'created_at' => 'created_at',
// other attributes...
'dynamic' => 'dynamic',
];
}
...
..in your action pass some dynamic values to your model, and return everything as JSON:
public function actionJson()
{
\Yii::$app->response->format = \yii\web\Response::FORMAT_JSON;
$model = Result::findOne(1);
$model->dynamic = [
'field1' => 'value1',
'field2' => 2,
'field3' => 3.33,
];
return $model;
}
In result you will get JSON like this:
{"id":1,"created_at":1499497557,"dynamic":{"field1":"value1","field2":2,"field3":3.33}}