How to keep the form fields filled in case of validation error Magento 2

Question

I have created a custom module for Distributor registration its having a custom form with some extra fields for registration. Distributor registration is working fine but i am not able to retain the form filed value in case there if there is server side validation error.

I have tried to followed customer registration module and form and found that Magento keeps the value in session like this.

in CreatePost.php controller

$this->session->setCustomerFormData($this->getRequest()->getPostValue());

and retaining the form value by bellow line of code in form.

<?php echo $block->escapeHtml($block->getFormData()->getCity()) ?>

Is there any other way i can use to keep the form filled in case of validation error ?

Answer 1

If you check Customer module in Magento 2, you will find that it is using $block->getFormData() function to get data.
Now when you go to Customer\Block\Form\Register block, you will find getFormData function,

public function getFormData()
{
    $data = $this->getData('form_data');
    if ($data === null) {
        $formData = $this->_customerSession->getCustomerFormData(true);
        $data = new \Magento\Framework\DataObject();
        if ($formData) {
            $data->addData($formData);
            $data->setCustomerData(1);
        }
        if (isset($data['region_id'])) {
            $data['region_id'] = (int)$data['region_id'];
        }
        $this->setData('form_data', $data);
    }
    return $data;
}

This function gets data from session you set in your controller with code

$this->_customerSession->setCustomerFormData($this->getRequest()->getPostValue());

and set it in a variable form_data which is used as $block->getFormData in phtml file. You also need to create the same function in your block to get data.