Pre-population of checkboxList with DynamicModel issue - yii2

Question

I have created a DynamicModel to build a search form which contains a checkboxList with the items being populated by the records of a model. The form works fine, however the form appears on the results page and all fields are populated with the previously selected values apart from the checkboxList.
Controller:
$model = DynamicModel::validateData(
['date_from',
'date_to',
'client_site',
'report_types',
]);
$model->addRule(['client_site'], 'integer');
$model->addRule(['client_site', 'report_types'], 'required');
$model->addRule(['date_from','date_to'], 'string');
$model->load(Yii::$app->request->post()) && $model->validate();
$reportTypes = ArrayHelper::map(ReportType::find()->asArray()->all, 'id', 'name');
return $this->render('print-report-form', [
'report_types' => $reportTypes,
'model' => $model,
]);
View:
<?= $form->field($model, 'report_types[]')
->inline(false)
->checkboxList($reportTypes);
?>
Do I need to tie the $reportTypes in within the model another way? Any ideas on why the selected checkboxes are not being pre-populated on the form submission?

Answer 1

First of all, there is a mistake in view form field, variable name is wrong, it should be
<?= $form->field($model, 'report_types[]')
->inline(false)
->checkboxList($report_types);
?>
then in controller
$model = DynamicModel::validateData(
['date_from',
'date_to',
'client_site',
'report_types',
]);
$model->addRule(['client_site'], 'integer');
$model->addRule(['client_site', 'report_types'], 'required');
$model->addRule(['date_from','date_to'], 'string');
$posted_model = clone $model;
$reportTypes = ArrayHelper::map(ReportType::find()->asArray()->all, 'id', 'name');
if($posted_model->load(Yii::$app->request->post()) && $posted_model->validate())
{
// save data or do as per your requirement with $posted_model
// if nothing to be done, and just rendering back to form then
return $this->render('print-report-form', [
'report_types' => $reportTypes,
'model' => $model, // line X
]);
}
else
{
return $this->render('print-report-form', [
'report_types' => $reportTypes,
'model' => $model, // line X
]);
}
This was happening because when the view was rendering the very first time, all checkbox are empty, but when submit the form the model gets filled up with POSTed data ie all its attribute are set and then always you were rendering POSTed model ie the model filled with data.
Now with the above situation you are not rendering POSTed model, you are always rendering empty new model.
This was the situation where you need empty checkbox.
Second Situation:
If you need checkbox to be prepopulated then
remove [] in form field
<?= $form->field($model, 'report_types')
->inline(false)
->checkboxList($report_types);
?>
and replace line X by
'model' => $posted_model,
Here you will get filled checkboxes