GravityForms - Use custom conditional logic to display other fields which are not supported out of the box by GF

functions.php

<?php
/**
 * Validates the custom mask date field format MM/YYYY.
 */
add_filter('gform_field_validation_8', function($result, $value, $form, $field) {
    $date_field_ids = [119, 120, 121]; // Field IDs of the custom date field

    if (!in_array($field->id, $date_field_ids)) {
        return $result;
    }

    if (empty($value)) {
        return $result;
    }

    $date_parts = explode('/', $value);
    if (count($date_parts) !== 2) {
        $result['is_valid'] = false;
        $result['message'] = 'Please enter date in MM/YYYY format';
        return $result;
    }

    $month = intval($date_parts[0]);
    $year = intval($date_parts[1]);
    $current_year = (int)date('Y');

    if ($month < 1 || $month > 12) {
        $result['is_valid'] = false;
        $result['message'] = 'Please enter a valid month (01-12)';
        return $result;
    }

    if ($year < 1950 || $year > $current_year) {
        $result['is_valid'] = false;
        $result['message'] = sprintf('Please enter a year between 1950 and %d', $current_year);
        return $result;
    }

    return $result;
}, 10, 4);

function validation_pass_based_on_date($field_value, $result) {
    if (empty($field_value)) {
        return $result;
    }

    $date_parts = explode('/', $field_value);
    if (count($date_parts) !== 2) {
        return $result;
    }

    $month = intval($date_parts[0]);
    $year = intval($date_parts[1]);

    if ($month < 1 || $month > 12) {
        return $result;
    }

    $current_year = (int)date('Y');
    if ($year < 1950 || $year > $current_year) {
        return $result;
    }

    try {
        $input_date = new DateTime(sprintf('%04d-%02d-01', $year, $month));
        $current_date = new DateTime();
        $interval = $current_date->diff($input_date);
        $year_diff = $interval->y + ($interval->m / 12);
    } catch (Exception $e) {
        return $result;
    }

    if ($year_diff >= 2) {
        $result['is_valid'] = true;
    }

    return $result;
}

/**
 * Validates the address field based on the custom date field value.
 */
add_filter('gform_field_validation_8_17', function($result, $value, $form, $field) {
    $address_date_value = rgpost('input_119'); // Date field ID
    
    return validation_pass_based_on_date($address_date_value, $result);
}, 10, 4);

add_filter('gform_field_validation_8_123', function($result, $value, $form, $field) {
    $address_date_value = rgpost('input_120'); // Date field ID
    
    return validation_pass_based_on_date($address_date_value, $result);
}, 10, 4);

add_filter('gform_field_validation_8_124', function($result, $value, $form, $field) {
    $address_date_value = rgpost('input_120'); // Date field ID
    
    return validation_pass_based_on_date($address_date_value, $result);
}, 10, 4);

add_filter('gform_field_validation_8_125', function($result, $value, $form, $field) {

    $currently_employed_field = rgpost('input_44');
    
    if( strtolower(trim($currently_employed_field)) === 'no' ){
        $result['is_valid'] = true;

        return $result;
    }
    
    $address_date_value = rgpost('input_121'); // Date field ID
    
    return validation_pass_based_on_date($address_date_value, $result);
}, 10, 4);

/**
 * Adds JavaScript for controlling address field visibility.
 */
add_action('wp_footer', function() {
    ?>
    <script type="text/javascript">
    document.addEventListener('gform/post_render', (event) => {
        const formId = 8;

        if (event.detail.formId !== formId) {
            return;
        }

        // Address related fields
        const dateFieldId = 119;
        const oldAddressFieldId = 17;
        const oldAddressDurationFieldId = 80;

        // Bank related fields
        const bankDateFieldId = 120;
        const previousBankFieldId = 123;
        const previousBankDurationFieldId = 78;
        const previousBankReasonFieldId = 124;

		// Employment related fields
		const employmentDateFieldId = 121;
		const previousEmploymentNameFieldId = 125;
		const previousEmploymentDurationFieldId = 79;

        // Address related elements
        const dateField = document.getElementById(`input_${formId}_${dateFieldId}`);
        const oldAddressField = document.getElementById(`field_${formId}_${oldAddressFieldId}`);
        const oldAddressDurationField = document.getElementById(`field_${formId}_${oldAddressDurationFieldId}`);

        // Bank related elements
        const bankDateField = document.getElementById(`input_${formId}_${bankDateFieldId}`);
        const previousBankField = document.getElementById(`field_${formId}_${previousBankFieldId}`);
        const previousBankDurationField = document.getElementById(`field_${formId}_${previousBankDurationFieldId}`);
        const previousBankReasonField = document.getElementById(`field_${formId}_${previousBankReasonFieldId}`);

		// Employment related elements
		const employmentDateField = document.getElementById(`input_${formId}_${employmentDateFieldId}`);
		const previousEmploymentNameField = document.getElementById(`field_${formId}_${previousEmploymentNameFieldId}`);
		const previousEmploymentDurationField = document.getElementById(`field_${formId}_${previousEmploymentDurationFieldId}`);

        if (!dateField || !oldAddressField || !oldAddressDurationField) return;
        if (!bankDateField || !previousBankField || !previousBankDurationField || !previousBankReasonField) return;
		if (!employmentDateField || !previousEmploymentNameField || !previousEmploymentDurationField) return;

        // Initially hide all conditional fields
        oldAddressField.style.display = 'none';
        oldAddressDurationField.style.display = 'none';
        previousBankField.style.display = 'none';
        previousBankDurationField.style.display = 'none';
        previousBankReasonField.style.display = 'none';

		previousEmploymentNameField.style.display = 'none';
		previousEmploymentDurationField.style.display = 'none';

        function isValidDate(month, year) {
            if (month < 1 || month > 12) return false;

            const currentYear = new Date().getFullYear();
            if (year < 1950 || year > currentYear) return false;
            
            return true;
        }

        function checkDateAndToggleFields(dateValue, fieldsToToggle) {
            const datePattern = /^(0[1-9]|1[0-2])\/([0-9]{4})$/;
            if (!datePattern.test(dateValue)) {
                fieldsToToggle.forEach(field => field.style.display = 'none');
                return;
            }

            const [monthStr, yearStr] = dateValue.split('/');
            const month = parseInt(monthStr);
            const year = parseInt(yearStr);

            if (!isValidDate(month, year)) {
                fieldsToToggle.forEach(field => field.style.display = 'none');
                return;
            }
            
            const inputDate = new Date(year, month - 1);
            const currentDate = new Date();
            
            const yearDiff = (currentDate.getFullYear() - inputDate.getFullYear()) +
                          (currentDate.getMonth() - inputDate.getMonth()) / 12;
            
            const displayStyle = yearDiff < 2 ? 'block' : 'none';
            fieldsToToggle.forEach(field => field.style.display = displayStyle);
        }

        function checkAddressDate() {
            checkDateAndToggleFields(dateField.value, [
                oldAddressField,
                oldAddressDurationField
            ]);
        }

        function checkBankDate() {
            checkDateAndToggleFields(bankDateField.value, [
                previousBankField,
                previousBankDurationField,
                previousBankReasonField
            ]);
        }

		function checkEmploymentDate() {
			checkDateAndToggleFields(employmentDateField.value, [
				previousEmploymentNameField,
				previousEmploymentDurationField
			]);
		}

        dateField.addEventListener('keyup', (e) => {
            const cursorPos = e.target.selectionStart;
            checkAddressDate();
            e.target.setSelectionRange(cursorPos, cursorPos);
        });

        bankDateField.addEventListener('keyup', (e) => {
            const cursorPos = e.target.selectionStart;
            checkBankDate();
            e.target.setSelectionRange(cursorPos, cursorPos);
        });

        employmentDateField.addEventListener('keyup', (e) => {
            const cursorPos = e.target.selectionStart;
            checkEmploymentDate();
            e.target.setSelectionRange(cursorPos, cursorPos);
        });

        // Initial check for both date fields
        checkAddressDate();
        checkBankDate();
        checkEmploymentDate();
    });
    </script>
    <?php
});

// exclude custom conditional fields from submission
add_filter('gform_pre_submission_8', 'exclude_conditional_fields');
function exclude_conditional_fields($form) {

    $address_date_value = $_POST['input_119']; // Date field ID
    $address_validation_result = validation_pass_based_on_date($address_date_value, []);

    if( is_array($address_validation_result) && isset($address_validation_result['is_valid']) ){
        unset($_POST['input_17_1']);
        unset($_POST['input_17_2']);
        unset($_POST['input_17_3']);
        unset($_POST['input_17_4']);
        unset($_POST['input_17_5']);
        unset($_POST['input_17_6']);

        unset($_POST['input_80']);
    }

    $bank_date_value = $_POST['input_120']; // Date field ID
    $bank_validation_result = validation_pass_based_on_date($bank_date_value, []);

    if( is_array($bank_validation_result) && isset($bank_validation_result['is_valid']) ){
        unset($_POST['input_123']);
        unset($_POST['input_78']);
        unset($_POST['input_124']);
    }

    $currently_employed_field = $_POST['input_44'];
	$employment_date_value = $_POST['input_121']; // Date field ID
    $employment_validation_result = validation_pass_based_on_date($employment_date_value, []);

    if( 
        strtolower(trim($currently_employed_field)) === 'no' ||
        ( is_array($employment_validation_result) && isset($employment_validation_result['is_valid']) ) ){
        unset($_POST['input_125']);
        unset($_POST['input_79']);
    }
}