How to write data to Yii2 intermediate table?

Question

Yii

Hello! Unable to write data to intermediate table.
Database schema:


Added a checkboxlist to the form for adding an entry (area), which displays a list of workers from the workers table:

<?= $form->field($model, 'workAreas')->checkboxList(ArrayHelper::map(Workers::find()->all(), 'id', 'name')) ?>

In AreaController.php:

public function actionCreate()
    {
        $model = new Area();
        $workarea = new WorkArea();

        if ($model->load(Yii::$app->request->post()) && $model->save()) {
            
            $workarea->area_id = $model->id;
            $workarea->worker_id = $model->workAreas;
            
          //$workarea->save();

            var_dump($workarea);

            return $this->redirect(['view', 'id' => $model->id]);
        }

        return $this->render('create', [
            'model' => $model,
        ]);
    }

In the Area.php model:

public function getWorkAreas()
    {
        return $this->hasMany(WorkArea::className(), ['area_id' => 'id']);
    }

All the data is leaving the form and all of them are correct:

var_dump($workarea) shows the required area_id, but the worker_id array is empty for some reason. I tried separately var_dump($model->workAreas), the array is also empty. If I substitute $workarea->worker_id = 7 (or any other) in the controller, then the entry in the database occurs correctly.

At this stage, I can’t understand why this is happening ( Please help me figure out why the data in the array is not visible. And also how to save the array correctly? So that the intermediate table looks like this:

Answer 1

Does the Area model have a property and rules for workAreas? How are they loaded from post into the model?
In the rules workAreas should be safe, then the array will be loaded and available. And yet, it must be translated into a string in order to save it to the database. worker_id must be of the appropriate type.