// http://www.gravityhelp.com/forums/topic/database-look-up-validation
// validate 7 digit code
// change the 3 here to your form ID
add_filter('gform_validation_3', 'validate_code');
function validate_code($validation_result){
    // this assumes the code is entered in field one on your form
    // change this input_ number if it's a different field
    if(!is_code_valid($csvdata, $id, $_POST['input_1'])){
        $validation_result['is_valid'] = false;
        foreach($validation_result['form']['fields'] as &$field){
        // field 1 is the field where we want to show the validation message
            if($field['id'] == 1){
                $field['failed_validation'] = true;
                $field['validation_message'] = 'The ABC ID you entered is invalid: please try again.';
                break;
            }
        }
    }
    return $validation_result;
}


// This creates the array from the data file in the fuction below
function csv_in_array($url,$delm=";",$encl="\"",$head=false) {

    $csvxrow = file($url);   // ---- csv rows to array ----

    $csvxrow[0] = chop($csvxrow[0]);
    $csvxrow[0] = str_replace($encl,'',$csvxrow[0]);
    $keydata = explode($delm,$csvxrow[0]);
    $keynumb = count($keydata);

    if ($head === true) {
    $anzdata = count($csvxrow);
    $z=0;
    for($x=1; $x<$anzdata; $x++) {
        $csvxrow[$x] = chop($csvxrow[$x]);
        $csvxrow[$x] = str_replace($encl,'',$csvxrow[$x]);
        $csv_data[$x] = explode($delm,$csvxrow[$x]);
        $i=0;
        foreach($keydata as $key) {
            $out[$z][$key] = $csv_data[$x][$i];
            $i++;
            }
        $z++;
        }
    }
    else {
        $i=0;
        foreach($csvxrow as $item) {
            $item = chop($item);
            $item = str_replace($encl,'',$item);
            $csv_data = explode($delm,$item);
            for ($y=0; $y<$keynumb; $y++) {
               $out[$i][$y] = $csv_data[$y];
            }
        $i++;
        }
    }

return $out;
}

// This calls the abcid.txt file and sends it to the processor function above
$csvdata = csv_in_array( "/home/abcid.txt", ";", "\"", true );



// This searches the array also making another array of just the abcid values
$id = 'abcid';
function is_code_valid($csvdata, $id, $thiscode) {
    $results = array();
    is_code_valid_r($array, $key, $value, $results);
    if($thiscode == $results[0]['#value']) {
        return TRUE;
    }
    // if we did not have a match and are out of codes, return FALSE
    return FALSE;
}

// This is the secondary array
function is_code_valid_r($array, $key, $value, &$results) {
    if (!is_array($array))
        return;

    if ($array[$key] == $value)
        $results[] = $array;

    foreach ($array as $subarray)
        is_code_valid_r($subarray, $key, $value, $results);
}


// doing this here because the redirect URL does not support variables or shortcodes
// change the 3 here to your form ID
add_filter('gform_confirmation_3', 'valid_invitation_confirmation', 10, 4);
function valid_invitation_confirmation($confirmation, $form, $lead, $ajax){
    // customize this URL - I send the code in the query string
    $success_url = 'www.example.com/registration-step-2/?abcid=' . $lead[1];
    $confirmation = array('redirect' => $success_url);
    return $confirmation;
}