Mryntu

<?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="rule_information" sortOrder="10">
 <field name="from_date" formElement="date">
 <argument name="data" xsi:type="array">
 <item name="config" xsi:type="array">
 <item name="options" xsi:type="array">
 <item name="dateFormat" xsi:type="string">yyyy-MM-dd</item>
 <item name="timeFormat" xsi:type="string">HH:mm:ss</item>
 <item name="showsTime" xsi:type="boolean">true</item>
 </item>
 </item>
 </argument>
 </field>
 <field name="to_date" formElement="date">
 <argument name="data" xsi:type="array">
 <item name="config" xsi:type="array">
 <item name="options" xsi:type="array">
 <item name="dateFormat" xsi:type="string">yyyy-MM-dd</item>
 <item name="timeFormat" xsi:type="string">HH:mm:ss</item>
 <item name="showsTime" xsi:type="boolean">true</item>
 </item>
 </item>
 </argument>
 </field>
 </fieldset>
</form>

This is my sales_rule_form.xml
i changed dB column as VARCHAR/datetime, its showing invalid date, and how can i save it in db.

This is a bug. Try following way for the fix:

app/code/SR/MagentoCommunity/etc/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="MagentoUiComponentFormElementDataTypeDate">
 <plugin name="SR_MagentoCommunity::allow_format_from_config"
 type="SRMagentoCommunityPluginUiComponentFormElementDataTypeDate" sortOrder="1"/>
 </type>
</config>

app/code/SR/MagentoCommunity/Plugin/Ui/Component/Form/Element/DataType/Date.ph

code>
<?php
namespace SRMagentoCommunityPluginUiComponentFormElementDataType;

class Date

 public function aroundPrepare(
 MagentoUiComponentFormElementDataTypeDate $subject,
 Closure $proceed
 ) 
 $configOrig = $subject->getData('config');
 $proceed();
 $config = $subject->getData('config');
 if (isset($configOrig['options']) && isset($configOrig['options']['dateFormat'])) 
 $config['options']['dateFormat'] = $configOrig['options']['dateFormat'];
 

 if (isset($configOrig['options']) && isset($configOrig['options']['timeFormat'])) 
 $config['options']['timeFormat'] = $configOrig['options']['timeFormat'];
 

 $subject->setData('config', $config);
 

[Update]

app/code/SR/MagentoCommunity/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">
 <preference for="MagentoSalesRuleControllerAdminhtmlPromoQuoteSave" type="SRMagentoCommunityControllerAdminhtmlPromoQuoteSave"/>
</config>

app/code/SR/MagentoCommunity/Controller/Adminhtml/Promo/Quote/Save.php

<?php
namespace SRMagentoCommunityControllerAdminhtmlPromoQuote;

class Save extends MagentoSalesRuleControllerAdminhtmlPromoQuoteSave

 /**
 * @var MagentoFrameworkStdlibDateTimeFilterDateTime
 */
 private $dateTimeFilter;

 /**
 * Save constructor.
 *
 * @param MagentoBackendAppActionContext $context
 * @param MagentoFrameworkRegistry $coreRegistry
 * @param MagentoFrameworkAppResponseHttpFileFactory $fileFactory
 * @param MagentoFrameworkStdlibDateTimeFilterDate $dateFilter
 * @param MagentoFrameworkStdlibDateTimeFilterDateTime $dateTimeFilter
 */
 public function __construct(
 MagentoBackendAppActionContext $context,
 MagentoFrameworkRegistry $coreRegistry,
 MagentoFrameworkAppResponseHttpFileFactory $fileFactory,
 MagentoFrameworkStdlibDateTimeFilterDate $dateFilter,
 MagentoFrameworkStdlibDateTimeFilterDateTime $dateTimeFilter
 ) 
 parent::__construct($context, $coreRegistry, $fileFactory, $dateFilter);
 $this->dateTimeFilter = $dateTimeFilter;
 

 /**
 * Promo quote save action
 *
 * @return void
 * @SuppressWarnings(PHPMD.CyclomaticComplexity)
 * @SuppressWarnings(PHPMD.NPathComplexity)
 */
 public function execute()
 
 if ($this->getRequest()->getPostValue()) 
 try 
 /** @var $model MagentoSalesRuleModelRule */
 $model = $this->_objectManager->create(MagentoSalesRuleModelRule::class);
 $this->_eventManager->dispatch(
 'adminhtml_controller_salesrule_prepare_save',
 ['request' => $this->getRequest()]
 );
 $data = $this->getRequest()->getPostValue();

 $filterValues = ['from_date' => $this->dateTimeFilter];
 if ($this->getRequest()->getParam('to_date')) 
 $filterValues['to_date'] = $this->dateTimeFilter;
 
 $inputFilter = new Zend_Filter_Input(
 $filterValues,
 [],
 $data
 );
 $data = $inputFilter->getUnescaped();

 $id = $this->getRequest()->getParam('rule_id');
 if ($id) 
 $model->load($id);
 if ($id != $model->getId()) 
 throw new MagentoFrameworkExceptionLocalizedException(__('The wrong rule is specified.'));
 
 

 $session = $this->_objectManager->get(MagentoBackendModelSession::class);

 $validateResult = $model->validateData(new MagentoFrameworkDataObject($data));
 if ($validateResult !== true) 
 foreach ($validateResult as $errorMessage) 
 $this->messageManager->addErrorMessage($errorMessage);
 
 $session->setPageData($data);
 $this->_redirect('sales_rule/*/edit', ['id' => $model->getId()]);
 return;
 

 if (isset(
 $data['simple_action']
 ) && $data['simple_action'] == 'by_percent' && isset(
 $data['discount_amount']
 )
 ) 
 $data['discount_amount'] = min(100, $data['discount_amount']);
 
 if (isset($data['rule']['conditions'])) 
 $data['conditions'] = $data['rule']['conditions'];
 
 if (isset($data['rule']['actions'])) 
 $data['actions'] = $data['rule']['actions'];
 
 unset($data['rule']);
 $model->loadPost($data);

 $useAutoGeneration = (int)(
 !empty($data['use_auto_generation']) && $data['use_auto_generation'] !== 'false'
 );
 $model->setUseAutoGeneration($useAutoGeneration);

 $session->setPageData($model->getData());

 $model->save();
 $this->messageManager->addSuccessMessage(__('You saved the rule.'));
 $session->setPageData(false);
 if ($this->getRequest()->getParam('back')) 
 $this->_redirect('sales_rule/*/edit', ['id' => $model->getId()]);
 return;
 
 $this->_redirect('sales_rule/*/');
 return;
 catch (MagentoFrameworkExceptionLocalizedException $e) 
 $this->messageManager->addErrorMessage($e->getMessage());
 $id = (int)$this->getRequest()->getParam('rule_id');
 if (!empty($id)) 
 $this->_redirect('sales_rule/*/edit', ['id' => $id]);
 else 
 $this->_redirect('sales_rule/*/new');
 
 return;
 catch (Exception $e) 
 $this->messageManager->addErrorMessage(
 __('Something went wrong while saving the rule data. Please review the error log.')
 );
 $this->_objectManager->get(PsrLogLoggerInterface::class)->critical($e);
 $this->_objectManager->get(MagentoBackendModelSession::class)->setPageData($data);
 $this->_redirect('sales_rule/*/edit', ['id' => $this->getRequest()->getParam('rule_id')]);
 return;
 
 
 $this->_redirect('sales_rule/*/');