filter_input_array POST和GET

Question

一旦我点击提交按钮，我会得到未定义的索引用户名，密码并记住。

<?php

$errors = array();
/* Form not submitted */
$input = array(
    'username'  => NULL,// POST //
    'password'  => NULL,// POST //
    'remember'  => NULL,// POST //
    'return'    => NULL// GET //
);
/* Form is submitted */
if(filter_has_var(INPUT_POST, 'submit')){

    $defs_POST = array(
        'username'  => FILTER_SANITIZE_STRING,
        'password'  => FILTER_UNSAFE_RAW,
        'remember'  => FILTER_SANITIZE_STRING
    );
    $defs_GET = array(
        'return'    => FILTER_SANITIZE_STRING
    );

    $input = filter_input_array(INPUT_POST, $defs_POST);
    $input = filter_input_array(INPUT_GET, $defs_GET);

    if(empty($input['username'])){
        $errors[] = 'Please enter your username.';
    }
    if(empty($input['password'])){
        $errors[] = 'Please enter your password.';
    }

}

if(filter_has_var(INPUT_POST, 'submit') and empty($errors)){

    /* QUERYs*/
    /* ..................*/

    if(!empty($input['return']))
        redirect(urldecode($input['return']));
    else
        redirect('index.php?do=home');

}

?>

............................................... .................................................. .................................................. ....... FORM

<!-- Login wrapper -->
    <div class="login-wrapper">
        <form method="post">
        <input type="hidden" name="csrfKey" value="{$csrfKey}">
        <input type="hidden" name="csrfToken" value="{$csrfToken}">
            <div class="popup-header">
                <a href="../" class="pull-left"><i class="icon-home4"></i></a>
                <span class="text-semibold">{$lang.global.a_0001}</span>
                <div class="btn-group pull-right">
                    <a href="#" class="dropdown-toggle" data-toggle="dropdown"><i class="icon-cogs"></i></a>
                    <ul class="dropdown-menu icons-right dropdown-menu-right">
                        <li><a href="#"><i class="icon-info"></i>{$lang.global.a_0002}</a></li>
                        <li><a href="#"><i class="icon-info"></i>{$lang.global.a_0003}</a></li>
                    </ul>
                </div>
            </div>
            <div class="well">
                <div class="form-group has-feedback">
                    <label>{$lang.global.a_0004}</label>
                    <input type="text" name="username" value="{$input.username}" class="form-control" placeholder="{$lang.placeholder.a_0001}">
                    <i class="icon-users form-control-feedback"></i>
                </div>

                <div class="form-group has-feedback">
                    <label>{$lang.global.a_0005}</label>
                    <input type="password" name="password" value="{$input.password}" class="form-control" placeholder="{$lang.placeholder.a_0002}">
                    <i class="icon-lock form-control-feedback"></i>
                </div>

                <div class="row form-actions">
                    <div class="col-xs-6">
                        <div class="checkbox checkbox-success">
                        <label>
                            <input type="checkbox" name="remember" value="{$input.remember}" class="styled">
                            {$lang.global.a_0006}
                        </label>
                        </div>
                    </div>

                    <div class="col-xs-6">
                        <button type="submit" name="submit" class="btn btn-default pull-right"><i class="icon-enter"></i>{$lang.button.a_0001}</button>
                    </div>
                </div>
            </div>
        </form>
    </div>  
    <!-- /login wrapper -->