framework/rest/ViewAction.php
public function run($id)
    {
        $model = $this->findModel($id);
        if ($this->checkAccess) {
            call_user_func($this->checkAccess, $this->id, $model);
        }

        return $model;
    }
public function run($id)
    {
        $model = $this->findModel($id);
        if ($this->checkAccess) {
            call_user_func($this->checkAccess, $this->id, $model);
        }

        return $model;
    }
Displays a model.
@param string $id the primary key of the model.
@return \yii\db\ActiveRecordInterface the model being displayed