Yii2 update related model makes insert - activerecord

Question

Depending on this question: Yii2 updating two related models does not show data of the second. I have manged calling the related model InvoiceItems to the Invoices model it hasMany relation.
However, updating leads to insert new records in invoice_items table instead of updating the current related records to the invoices table.
I tried to add the id field of each InvoiceItems record in the _form view to solve this issue, but it still exist.
The following is actionUpdate of the InvoicesController:
public function actionUpdate($id)
{
$model = $this->findModel($id);
//$invoiceItems = new InvoiceItems();
$count = count(Yii::$app->request->post('InvoiceItems', []));
//Send at least one model to the form
$invoiceItems = [new InvoiceItems()];
//Create an array of the products submitted
for($i = 1; $i < $count; $i++) {
$invoiceItems[] = new InvoiceItems();
}
if ($model->load(Yii::$app->request->post()) && $model->save()) {
//$invoiceItems->invoice_id = $model->id;
if (Model::loadMultiple($invoiceItems, Yii::$app->request->post())){
foreach ($invoiceItems as $item){
$item->invoice_id = $model->id;
//$item->id = $model->invoiceItems->id;
$item->save(false);
}
return $this->redirect(['view', 'id' => $model->id]);
}
else{
return var_dump($invoiceItems);
}
} else {
//$invoiceItems->invoice_id = $model->id;
$invoiceItems = $this->findInvoiceItemsModel($model->id);
return $this->render('update', [
'model' => $model,
'invoiceItems' => $invoiceItems,
]);
}
}
This is the code of _form view of InvoicesController:
<div class="invoices-form">
<?php $form = ActiveForm::begin(); ?>
<?= $form->field($model, 'created')->textInput() ?>
<?= $form->field($model, 'type')->textInput(['maxlength' => true]) ?>
<hr />
<?php if (is_array($invoiceItems)): ?>
<?php foreach ($invoiceItems as $i => $item): ?>
<?= $form->field($item, "[$i]id")->textInput();?>
<?= $form->field($item, "[$i]item_id")->textInput();?>
<?= $form->field($item, "[$i]unit_id")->textInput();?>
<?= $form->field($item, "[$i]qty")->textInput();?>
<?php endforeach; ?>
<?php else: ?>
<?= $form->field($invoiceItems, "item_id")->textInput();?>
<?= $form->field($invoiceItems, "unit_id")->textInput();?>
<?= $form->field($invoiceItems, "qty")->textInput();?>
<?php endif; ?>
<div class="form-group">
<?= Html::submitButton($model->isNewRecord ? Yii::t('app', 'Create') : Yii::t('app', 'Update'), ['class' => $model->isNewRecord ? 'btn btn-success' : 'btn btn-primary']) ?>
</div>
<?php ActiveForm::end(); ?>
</div>
The following screen shot, visually, demonstrates what I have got:

Answer 1

if you in update you don't need new record you should remove
this part
$count = count(Yii::$app->request->post('InvoiceItems', []));
//Send at least one model to the form
$invoiceItems = [new InvoiceItems()];
//Create an array of the products submitted
for($i = 1; $i < $count; $i++) {
$invoiceItems[] = new InvoiceItems();
}
The $invoiceItems you create in this way are obviuosly "new" and then are inserted ..for an update the model must to be not new..
You have already the related models to save they came from post.. and from load multiple
If you however need to manage new model (eg: because you added new record in wide form update operation) you can test
$yourModel->isNewRecord
and if this is new check then if the user have setted properly the related fields you can save it with
$yourModel->save();
otherwise you can simple discart.. (not saving it)

Answer 2

I am pretty sure that this code below of course fills a array named $invoiceItems with the submitted data.
if (Model::loadMultiple($invoiceItems, Yii::$app->request->post())){
foreach ($invoiceItems as $item){
$item->invoice_id = $model->id;
//$item->id = $model->invoiceItems->id;
$item->save(false);
}
}
But all $items have the scenario "insert" (could be that you allow the setting of the attribute 'ID' but normally this isn't allowed in the Gii generated code. and then you get "new items" whenever you save.
if you add a return var_dump($invoiceItems);after the loadMultiple you will see that only the safe attributes are filled with the submitted data.
You are also not validating them before saving, which is also kind of bad.
if (Model::loadMultiple($invoiceItems, Yii::$app->request->post()) && Model::validateMultiple($invoiceItems)) {
http://www.yiiframework.com/doc-2.0/guide-input-tabular-input.html

Answer 3

According to scaisEdge answer and this widget documentation. I could able to determine the problem solution.
Simply, in my code I neglected the relation between the two models, when I say:
$count = count(Yii::$app->request->post('InvoiceItems', []));
//Send at least one model to the form
$invoiceItems = [new InvoiceItems()];
The value of $invoiceItems should be obtained using the relation like the following:
$invoiceItems = $model->invoiceItems;
However, I still have another issue with adding new records to the related model InvoiceItems during the update.