如何将我从下拉列表中选择的数据附加到yii2中的下一个输入字段

Question

I want to select courses from the course field, then let it show in my courses field and submit the courses to the database. or if someone can help me so my courses can appear has a checkbox and once i tick a checkbox, it appears in the courses field

<?php $form = ActiveForm::begin(); ?>
<?=$form->field($model, 'student_id') ?>
<?=
$form->field($model, 'faculty_id')->dropDownList(
        ArrayHelper::map(Faculties::find()->asArray()->all(), 'faculty_id', 'faculty_name'), [
    'prompt' => 'Select Faculty',
    'onchange' => '$.post("' . Yii::$app->urlManager->createUrl('/departments/lists?id=') . '"+$(this).val(), function(data) {
                            $("select#registrations-department_id").html (data);
                        });'
        ]
);
?>
<?=
$form->field($model, 'department_id')->dropDownList(
        ArrayHelper::map(Departments::find()->asArray()->all(), 'department_id', 'department_name'), [
    'id' => 'registrations-department_id',
    'prompt' => 'Select Department',
    'onchange' => '$.post("' . Yii::$app->urlManager->createUrl('/courses/lists?id=') . '"+$(this).val(), function(data) {
                            $("select#registrations-course_id").html (data);
                        });'
]);
?>

<?=
$form->field($model, 'course_id')->dropDownList(
        ArrayHelper::map(Courses::find()->asArray()->all(), 'course_id', 'course_name'), [
    'id' => 'registrations-course_id',
    'prompt' => 'Select Course',
    'onchange' => '$.post("(selected:)."+$(this).val(), function(data){
                            $("#registrations-courses").append(data)
                        });'
]);
?>
<!--        <?//= $form->field($model, 'courses')->checkBoxList([]) ?> -->


<?=$form->field($model, 'courses') ?>
<?=$form->field($model, 'comment') ?>
<?=$form->field($model, 'status') ?>
<?=$form->field($model, 'created_at') ?>
<?=$form->field($model, 'updated_at') ?>

<div class="form-group">
    <?=Html::submitButton('Submit', ['class' => 'btn btn-primary']) ?>
</div>
<?php ActiveForm::end(); ?>

EDIT

this is my controller how do I save the courses in the database in the same column?

 public function actionCreate()
{
    $model = new Registrations();

    if ($model->load(Yii::$app->request->post())) {
        if ($model->validate()) {
            // form inputs are valid, do something here
            $model->student_id = Yii::$app->user->identity->id;
            $model->faculty_id = 1 ;
            $model->department_id = null ;
            $model->course_id = 1;
            $model->save();
            return $this->redirect('../site/profile');
        }
    }
    return $this->render('create', [
        'model' => $model,
    ]);
}

Answer 1

You can use the checkBoxList() to create the list of checkboxes based on the courses list.

Change your course_id field to the following

$form->field($model, 'course_id')->checkboxList(yii\helpers\ArrayHelper::map(Courses::find()->asArray()->all(), 'course_id', 'course_name'), [
    'inline' => true, 
    'unselect'=>null,
    'item' => function($index, $label, $name, $checked, $value){
        $checked = $checked ? 'checked' : '';
        return "<input type='checkbox' class='my-courses' name='{$name}' value='{$value}' {$checked} data-label='{$label}'>&nbsp;<label>{$label}</label>";
    }]);

add an id attribute to your courses field like below

$form->field($model, 'courses', ['inputOptions' => ['id' => 'courses']]);

and then add this javascript code to the top of your page

$js = <<< JS
        $(".my-courses").on('click',function(e){
                let course_name=$(this).data('label');
                let course_field=$("#courses");
                if($(this).is(":checked")){
                    $("#courses").val()==''?course_field.val(course_name):course_field.val(course_field.val()+', '+ course_name);
                }else{
                    let regex=new RegExp(',{0,1}\\\s{0,1}('+course_name+')','g');
                    course_field.val(course_field.val().replace(regex,''));
                }
            })
JS;
$this->registerJs($js, \yii\web\View::POS_READY);

Now if you select the checkbox the name of the course would be copied to the input field and when you submit your form you can get the fields in your $_POST array under your specific model index like below.

[course_id] => Array
                (
                    [0] => 1
                    [1] => 2
                )

[courses] => asdas, shugal, spoon

You can verify by adding a print_r(Yii::$app->request->post()) in your controller action inside the check

if($model->load(Yii::$app->request->post())){
     print_r(Yii::$app->request->post());

You can iterate on the course_id to save all of the course_id that were selected as checkboxes.