Magento 2 : Pre fill Textarea Value

Question

I added a text area in the admin form and want to show pre-defined text in that. So is it possible and How?

$fieldset->addField(
                'approval_note',
                'textarea',
                [
                'name' => 'approval_note',
                'label' => __('Thank you Note'),
                'title' => __('Thank you Note')
                ]
            );

I want to show text with the below data by default.

Need Help !!

Answer 1

Try with below code

$fieldset->addField(
    'approval_note',
    'textarea',
    [
    'name' => 'approval_note',
    'label' => __('Thank you Note'),
    'title' => __('Thank you Note'),
    'value' => 'Hello Symon,
How are you?
Thanks for contacting me.'
    ]
);

Answer 2

For Custom Form

$fieldset->addField(
    'approval_note',
    'textarea',
    [
    'name' => 'approval_note',
    'label' => __('Thank you Note'),
    'title' => __('Thank you Note'),
    'values' => 'Default Value'
    ]
);

For System Config

You can give a default value to the Textarea field by creating a config.xml file.
Place your file in the below-mentioned path

namespace\modulename\etc\config.xml

and add code as below and change "Section Name" and "Group Name" according to your system.xml file.

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
    <default>
        <sectionname>
            <groupname>
                <description>Textarea default text</description>
            </groupname>
        </sectionname>
    </default>
</config>

Answer 3

If simple "Value" not working then you can add renderer as below.

add below code in your form block e.g main.php

 $fieldset->addType(
            'htmldata',
            '\Vendor\Module\Block\Adminhtml\Items\Renderer\Autofill'
  );
    
   $fieldset->addField(
            'approval_note',
            'htmldata',
            ['name' => 'approval_note', 'label' => __('Thank you Note'), 'title' => __('Product Cost Notes'), 'required' => false,'nl2br' => true,
                'escape' => true]
        );

add new file Autofill.php as per definded path in file "Vendor\Module\Block\Adminhtml\Items\Renderer" and add below code

<?php 
namespace Vendor\Module\Block\Adminhtml\Items\Renderer;
 
/**
* CustomFormField Customformfield field renderer
*/
class Autofill extends \Magento\Framework\Data\Form\Element\AbstractElement
{
    /**
    * Get the after element html.
    *
    * @return mixed
    */
    public function getElementHtml()
    {
        // here you can write your code.
        if($this->getValue()){
            $enquiryData = nl2br($this->getValue());
        }else{
        /*default value
            $enquiryData = "Your default text here";
        }
        return $enquiryData;
    }
}

accept as a solution and do upvote if its works for you.