Php 检查字段的长度是否大于零

在下面的代码段中，已为联机表单创建了数据包，但如果其中一个字段故意留空，则会抛出错误。我如何修改它，如果字符串长度大于0，就创建数据包，如果不是，就不要设置它或者不定义它

$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;

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isset（），empty（）strlen（）？使用N/A或不可用或未定义预填充表单字段。除非用户为表单字段设置一个值，否则该值不会更改。@John猜想我指的是strlen（）