Yii2 - Dropdownlist OnChange to Display Other Model Attribute - yii2

Question

I have these Model Classes
Model:Subject
public function attributeLabels()
{
return [
'subject_id' =>Yii::t('app', 'ID'),
'subject_title' => Yii::t('app', 'Subject Title'),
];
}
Model:Grouping
public function attributeLabels()
{
return [
'grouping_id' => Yii::t('app', 'Grouping ID'),
'grouping_name' => Yii::t('app', 'Grouping Name'),
];
}
Model:SubjectGrouping
public function attributeLabels()
{
return [
'subject_grouping_id' => 'Subject Grouping ID',
'subject_grouping_grouping_id' => 'Subject Grouping Grouping ID',
'subject_grouping_subject_id' => 'Subject Grouping Subject ID',
];
}
Model:Exam
public function attributeLabels()
{
return [
'exam_id' =>Yii::t('app', 'ID'),
'exam_name' => Yii::t('app', 'Exam Name'),
'exam_group_id' => Yii::t('app', 'Exam Group'),
];
}
Model:SubjectGrouping has Foreign Keys from Model: Grouping (subject_grouping_grouping_id) and Model:Subject (subject_grouping_subject_id)
In Model:Exam, exam_group_id relates to subject_grouping_grouping_id in Model:SubjectGrouping.
Controller
public function actionCreate()
{
$model = new Exam();
if (Yii::$app->request->isAjax && $model->load(Yii::$app->request->post())) {
\Yii::$app->response->format = \yii\web\Response::FORMAT_JSON;
return ActiveForm::validate($model);
}
if ($model->load(Yii::$app->request->post())) {
$model->attributes = $_POST['Exam'];
$model->save();
return $this->redirect(['index']);
} else {
return $this->render(
'create', [
'model' => $model
]
);
}
}
View
<div class="col-xs-12 col-sm-4 col-lg-4">
<?=$form->field($model, 'exam_name')->textInput(['maxlength' => 50, 'placeholder' => 'Enter Exam Name'])?>
</div>
<div class="col-xs-12 col-sm-4 col-lg-4">
<?=$form->field($model, 'exam_group_id')->widget(
Select2::classname(), [
'data' => ArrayHelper::map(app\models\Grouping::find()->all(), 'grouping_id', 'grouping_name'),
'language' => 'en',
'options' => ['placeholder' => '--- Select Grouping ---'],
'pluginOptions' => [
'allowClear' => true
]
]
);
?>
</div>
From the diagram, how do I achieve these?
when Dropdownlist for exam_group_id is onChange the list of subjects with respect to grouping is displayed using the relationship between Model: SubjectGrouping and Model: Subject.
Others fields such as exam_name (textInput) and exam_group_id (Dropdownlist) should be save into the Model: Exam. But the subject list should not be saved. It is only for display purpose.
How do I achieve these?
I am using kartik\widgets\Select2 for the dropdownlist

Answer 1

I have done similar code by Kartik extension for state and country data.
here is the code for that.
<?php
//in view use this
use kartik\widgets\DateTimePicker; // or kartik\select2\Select2
use kartik\widgets\DepDrop;
use kartik\widgets\Select2;
?>
<?php
echo
$form->field($model, 'country_id')->widget(
Select2::className(),
[
'data' => \yii\helpers\ArrayHelper::map(common\models\Country::find()->all(), 'id', 'name'),
'options' => [
'id' => 'country_id',
'prompt' => Yii::t('aspns', 'Select')
]
]
);
?>
<?php
echo
$form->field($model, 'state_id')->widget(
DepDrop::classname(),
[
'data' => !empty($model->state_id) ? \yii\helpers\ArrayHelper::map(common\models\State::find()->where(['country_id' => $model->country_id])->all(), 'id', 'name') : [],
'options' => ['id' => 'state_id', 'placeholder' => Yii::t('aspns', 'Select')],
'pluginOptions' => [
'depends' => ['country_id'],
'url' => Url::to(['//country/get-states'])
]
]
)->label(Yii::t('aspns', 'State'));
?>
// In Controller section you need to do this
public function actionGetStates() {
$out = [];
if (isset($_POST['depdrop_parents'])) {
$parents = $_POST['depdrop_parents'];
if ($parents != null) {
$country_id = (int)$parents[0];
$out = State::find()->where(['country_id'=>$country_id])->select(['id', 'name'=>'name'])->asArray()->all();
return Json::encode(['output'=>$out, 'selected'=>'']);
}
}
return Json::encode(['output'=>'', 'selected'=>'']);
}
Change the code according to your requirement.
Thanks