检查字段长度大于零

Question

在下面的代码段中，已为在线表单创建了一个数据包，但如果其中一个字段有意留空，则会引发错误。我如何修改这个，以便说如果字符串长度大于0，创建数据包，如果没有，只是不设置它或保持未定义？

$formData = $_POST['form'];//form post value

 // Create vendor packet
    $oVendor = new stdClass();
    $oVendor->office_name = $formData['vendor_info'][1]['vendor_bus'];
    $oVendor->first_name = $formData['vendor_info'][1]['vendor_first'];
    $oVendor->middle_name = $formData['vendor_info'][1]['vendor_middle'];
    $oVendor->last_name = $formData['vendor_info'][1]['vendor_last'];

    $oVendor->business_address = array(
        'street' => $formData['vendor_address'][1]['vendor_street'],
        'city' => $formData['vendor_address'][1]['vendor_city'],
        'state' => $formData['vendor_address'][1]['vendor_state'],
        'zip' => $formData['vendor_address'][1]['vendor_zip'],
        'is_primary' => $formData['vendor_address'][1]['checkbox_primary']);

    $oVendor->mailing_address = array(
        'street' => $formData['vendor_mail'][1]['vendor_street'],
        'city' => $formData['vendor_mail'][1]['vendor_city'],
        'state' => $formData['vendor_mail'][1]['vendor_state'],
        'zip' => $formData['vendor_mail'][1]['vendor_zip'],
        'is_primary' => $formData['vendor_mail'][1]['checkbox_primary']);

        $emails = array();
    $i = 1;
    foreach($formData['vendor_emails'] as $email)
        $emails[$i++] = $email['vendor_email'];

    $oVendor->emails = $emails;