yii2: Undefined variable: model - yii2-advanced-app

Question

I am just starting Yii2 framework.
I want to create a dropdown list which is 1 to 10 and a submit button
Once select the option and click the button should go to next page to show the number I choose.
In my view file : index.php
use yii\widgets\ActiveForm;
<?php $form = ActiveForm::begin(); ?>
<?= $form->field($model, 'QTY')->dropDownList(range(1, 10)) ?>
<?= Html::submitButton('Buy', ['class' => 'btn btn-primary']) ?>
<?php ActiveForm::end(); ?>
Then when I go to the page it gave me 'Undefined variable: model' at dropdown list there.
What should I do to make it correct?
And what is the different between Html and CHtml?
Thanks.

Answer 1

this code is form.php not index.php.
because we can see, there are active form.
your model is undefined maybe you write the wrong code
this is example of controller index.php
public function actionIndex()
{
$searchModel = new PersediaanBarangSearch();
$dataProvider = $searchModel->search(Yii::$app->request->queryParams);
return $this->render('index', [
'searchModel' => $searchModel,
'dataProvider' => $dataProvider,
]);
}
Html and Chtml is the same
in Yii1=CHtml
in Yii2=Html

Answer 2

This is ment to be pagination? If yes use default functionality of the grid view.
This goes to controller:
$query = Post::find()->where(['status' => 1]);
$provider = new ActiveDataProvider([
'query' => $query,
'pagination' => [
'pageSize' => 10,
],
'sort' => [
'defaultOrder' => [
'created_at' => SORT_DESC,
'title' => SORT_ASC,
]
],
]);
return $this->render('path_to_view',['dataProvider'=>$provider]);
Read more
This goes to view:
GridView::widget([
'dataProvider' => $dataProvider,
'columns' => [
'id',
'name',
'created_at:datetime',
// ...
],
]);
Read more

Answer 3

Actually you model is not loaded, Please check below example.
public function actionIndex($id = Null)
{
$data=array();
$data['model'] = !empty($id) ? \app\models\YourModel::findOne($id) : new \app\models\YourModel();
return $this->render('index', $data);
}