How to grab the value of a dropDownList in Yii2? - yii2

Question

I am not grabbing the selected value ($model->attribute) on a dropDownList in Yii2, what could be wrong? Thanks
This is the code that is located on a View:
$command = $connection->createCommand('SELECT att1
FROM table
ORDER By table_id ASC');
$rows = $command->queryAll();
$command->execute();
$listData = ArrayHelper::index($rows, null, 'table_id');
Then on the same View I call to $listData
<div class="row">
<div class="col-lg-9">
<?php Pjax::begin(['enablePushState' => false]); ?>
<?php $form = ActiveForm::begin(['id' => 'test-form', 'options' => ['data-pjax' => true]
]); ?>
<?= $form->field($model, 'attribute')->dropDownList($listData, ['prompt'=>'List of attributes.']); ?>
<div class="form-group">
<?= Html::submitButton('Submit', ['class' => 'btn btn-primary', 'name' => 'test-button']) ?>
</div>
<?php ActiveForm::end(); ?>
<?php Pjax::end(); ?>
</div>
</div>
This is the Controller:
public function actionTest()
{
$model = new TestForm();
if ($model->load(Yii::$app->request->post()) && $model->validate()) {
$model->insertTest();
return $this->renderAjax('test', ['model' => $model]);
} else {
return $this->renderAjax('test', ['model' => $model]);
}
}
The Model has the definition of $attribute and insertTest() is a function that use the value of $attribute to query onto a DB.

Answer 1

Thinking of you should use
ArrayHelper::map($listData, 'table_id', 'table_id');
Because you need a one-dimensional array.
And it's better to use the ActiveRecord for queries to the database.
ArrayHelper Docs

Answer 2

You are selecting only att1 from table so you should map this column
$listData = ArrayHelper::index($rows, 'att1');
for debug try modify your actionTest commenting $model->insertTest(); and using $model->save();
if the value is saved in db then you should check inside you $model->insertTest() function
public function actionTest()
{
$model = new TestForm();
if ($model->load(Yii::$app->request->post()) && $model->validate()) {
// $model->insertTest();
$model->save();
return $this->renderAjax('test', ['model' => $model]);
} else {
return $this->renderAjax('test', ['model' => $model]);
}
}

Answer 3

you should use map in ArrayHelper
$listdata = ArrayHelper::map(CategoryModel::find()->orderBy(['table_id' => SORT_ASC])->all(), 'table_id', 'table_text');
Note: 'table_text' is table attribute that will appear in dropdown label.

Answer 4

I found the solution to that issue.
By doing this way the form was not able to save the submitted information.
$command = $connection->createCommand('SELECT att1
FROM table
ORDER By table_id ASC');
$rows = $command->queryAll();
$command->execute();
$listData = ArrayHelper::index($rows, null, 'table_id');
However, by this way the form is able to grab the value selected and put it into the variable.
$rows = table::find()->all();
$listData = ArrayHelper::map($rows,'table_id','att1');