Magento 2: Cart price rule Actions dynamically add text field using UI Components

You can add your custom dynamic fields to the sales rule form by customizing the vendor/magento/module-sales-rule/view/adminhtml/ui_component/sales_rule_form.xml file.

To customize the above file, we need to create a custom module and customize this file in the below path:

app/code/Vendor/Module/view/adminhtml/ui_component/sales_rule_form.xml

The customization code should be like the below code:

    <?xml version="1.0" encoding="UTF-8"?>
<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
    <fieldset name="actions" sortOrder="30">

        <dynamicRows name="dynamic_rows" sortOrder="0">
            <settings>
                <addButtonLabel translate="true">Add Record</addButtonLabel>
                <additionalClasses>
                    <class name="admin__field-wide">true</class>
                </additionalClasses>
                <componentType>dynamicRows</componentType>
            </settings>
            <container name="record" component="Magento_Ui/js/dynamic-rows/record">
                <argument name="data" xsi:type="array">
                    <item name="config" xsi:type="array">
                        <item name="isTemplate" xsi:type="boolean">true</item>
                        <item name="is_collection" xsi:type="boolean">true</item>
                        <item name="componentType" xsi:type="string">container</item>
                    </item>
                </argument>
                <field name="field_1" formElement="input">
                    <argument name="data" xsi:type="array">
                        <item name="config" xsi:type="array">
                            <item name="fit" xsi:type="boolean">false</item>
                        </item>
                    </argument>
                    <settings>
                        <validation>
                            <rule name="required-entry" xsi:type="boolean">true</rule>
                        </validation>
                        <dataType>text</dataType>
                        <label>Field #1</label>
                    </settings>
                </field>

                <actionDelete template="Magento_Backend/dynamic-rows/cells/action-delete">
                    <argument name="data" xsi:type="array">
                        <item name="config" xsi:type="array">
                            <item name="fit" xsi:type="boolean">false</item>
                        </item>
                    </argument>
                    <settings>
                        <additionalClasses>
                            <class name="some-class">true</class>
                        </additionalClasses>
                        <dataType>text</dataType>
                        <label>Actions</label>
                        <componentType>actionDelete</componentType>
                    </settings>
                </actionDelete>
            </container>
        </dynamicRows>
    </fieldset>
</form>

The output will look like this:

To save the custom field in salesrule table:

The salesrules are saved into the salesrule table by sales_rule/promo_quote/save controller. You can find this controller by looking into the network tab while saving the rule. Pls check the attached screenshot

From that above controller, we can now know the controller page. The controller path will be vendor/magento/module-sales-rule/Controller/Adminhtml/Promo/Quote/Save.php

From the above Save.php file, you can find a line $model->save(); which means, the salesrule table Model and resource Model are:

Model => vendor/magento/module-sales-rule/Model/Rule.php ResourceModel => vendor/magento/module-sales-rule/Model/ResourceModel/Rule.php

Every table data is saved from the ResourceModel's save method. So we can customize the save method to inject our new data. For this follow the below steps:

Step 1:

Declare a plugin for vendor/magento/module-sales-rule/Model/ResourceModel/Rule.php class save method in your custom module.

app/code/Vendor/Module/etc/adminhtml/di.xml

<?xml version="1.0"?>
    <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    
        <type name="Magento\SalesRule\Model\ResourceModel\Rule">
            <plugin name="before_save_rule" type="Vendor\Module\Plugin\BeforeSaveCartRule" sortOrder="10"/>
        </type>
    </config>

Step 2: create a plugin class and write the save logic method:

app/code/Vendor/Module/Plugin/BeforeSaveCartRule.php

<?php
declare(strict_types=1);

namespace Vendor\Module\Plugin;

use Magento\Framework\App\RequestInterface;
use Magento\SalesRule\Model\ResourceModel\Rule;

class BeforeSaveCartRule
{
    /**
     * @var RequestInterface
     */
    private $request;

    public function __construct(
        RequestInterface $request
    ) {
        $this->request = $request;
    }
    public function beforeSave(Rule $subject, $object) {
        $data = $this->request->getPostValue();

        $convertedToJson = json_encode($data['dynamic_rows']);
        $object->setCustomField($convertedToJson); /*Here you have to mention your custom field name. 
                                                    For example if the custom field is multiple_actions then the method should be like setMultipleActions()*/

        return null;
    }
}

In the below screenshot you can see, how your custom dynamic fields data is posted from request. I saved this custom field by converting it into an JSON and saved in custom field. You can customise it as per your need and save it.

Once you saved the salesrule you can check your salesrule table and you can see the saved custom field value

Result:

Note: Once you saved the salesrule you cannot find the saved data into your sales rule admin form. Only you can find the data in your database salesrule table, because you might need some dataprovider customisation to fetch and display the data into your custom dynamic row field.