/**
 * Custom shortcode to calculate and display the result on a page.
 */
function calculate_result_shortcode() {
    // Get the submitted form entry.
    $entry_id = FrmAppHelper::get_param( 'entry' );
    $entry = FrmEntry::getOne( $entry_id );
    $form_id = $entry->form_id;
	
	// Calculate the result for vloerverwarming.
	$result = calculate_result_zonnepanelen( $entry );

	// Format the result to display two decimals, change the decimal symbol to a comma, and remove the thousand separator.
	$formatted_result = number_format( $result, 2, ',', '' );

	return $formatted_result;
}
add_shortcode( 'calculate_result', 'calculate_result_shortcode' );

Why is my $form_id always empty in the above PHP code I wrote? I want to do check on the form_id because I want to do different calculations based on what form was used in the same shortcode as I am using that shortcode in a page I show on confirmation. Can anyone help me out?

Edit: added the functions below

/**
 * Custom function to calculate the result of vloerverwarming based on the given parameters.
 *
 * @param object $entry  The form entry object.
 *
 * @return float         The calculated result.
 */
function calculate_result_vloerverwarming( $entry ) {
    // Get the value of the number field
    $field1_value = FrmProEntriesController::get_field_value_shortcode( array( 'field_id' => '67', 'entry' => $entry ) );

    // Get the selected option from the dropdown field
    $dropdown_value = FrmProEntriesController::get_field_value_shortcode( array( 'field_id' => '66', 'entry' => $entry ) );

    // Perform the calculation based on the selected option and multiplication factor.
    if ( $dropdown_value === 'Droog' ) {
        $result = $field1_value * 32;
    } else {
        $result = $field1_value * 58;
	}
	
	$result = apply_building_year_calculation( $entry, $result, '65' );

    return $result;
}

/**
 * Custom function to calculate the result for zonnepanelen based on the given parameters.
 *
 * @param object $entry  The form entry object.
 *
 * @return float         The calculated result.
 */
function calculate_result_zonnepanelen( $entry ) {
    // Get the value of the dropdown field
    $dropdown_value = FrmProEntriesController::get_field_value_shortcode( array( 'field_id' => '53', 'entry' => $entry ) );

    // Get the value of the number field for available surface in square meters
    $surface_value = FrmProEntriesController::get_field_value_shortcode( array( 'field_id' => '54', 'entry' => $entry ) );

    // Get the value of the number field for yearly energy consumption
    $energy_consumption = FrmProEntriesController::get_field_value_shortcode( array( 'field_id' => '61', 'entry' => $entry ) );

    // Calculate the energy production based on available surface
    $energy_production = $surface_value * 200;

    // Determine the factor to multiply based on the dropdown selection
    $multiplication_factor = ( $dropdown_value === 'Plat' ) ? 1 : 1.15;

    // Check if the energy production exceeds the energy consumption
    if ( $energy_production > $energy_consumption ) {
        // Use the energy consumption as the upper limit
        $result = $energy_consumption * 1.36 * $multiplication_factor;
    } else {
        // Use the energy production multiplied by 1.36 and the multiplication factor
        $result = $energy_production * 1.36 * $multiplication_factor;
    }
	
    // Apply the building year calculation to the result
	$result = apply_building_year_calculation( $entry, $result, '52' );

    return $result;
}

/**
 * Apply the building year calculation to the result.
 *
 * @param object $entry   The form entry object.
 * @param float  $result  The current result.
 * @param float  $building_year_field_id  The building year field id.
 *
 * @return float          The result with the building year calculation applied.
 */
function apply_building_year_calculation( $entry, $result, $building_year_field_id ) {
    // Get the value of the slider field
    $building_year = FrmProEntriesController::get_field_value_shortcode( array( 'field_id' => $building_year_field_id, 'entry' => $entry ) );

    // Get the current year.
    $current_year = intval( date( 'Y' ) );

    // Calculate the age of the building.
    $building_age = $current_year - intval( $building_year );

    // Set the multiplication factor based on the building age.
    $multiplication_factor = ( $building_age < 10 ) ? 1.21 : 1.06;

    // Apply the multiplication factor to the result.
    $result *= $multiplication_factor;

    return $result;
}