这让我朝着正确的方向前进。这是我想到的。我决定创建一个短代码，这样我就可以把它放到任何需要的地方。使用get\\u page\\u by\\u title（）还可以查找帖子，即使它们的帖子类型在传统搜索中是隐藏的。

function esm_search($atts) {
        extract(shortcode_atts(array(
                "label_codeword" => \'Codeword\',
                "label_submit" => \'Submit\'
        ), $atts));

        if ($_SERVER[\'REQUEST_METHOD\'] == \'POST\') {
                $error = false;
                foreach ($_POST as $field => $value) {
                        if (get_magic_quotes_gpc()) {
                                $value = stripslashes($value);
                        }
                        $form_data[$field] = strip_tags($value);
                }

                if( $form_data[\'codeword\'] != "") {
                        $esmID = get_page_by_title($form_data[\'codeword\'],"","esm" );
                        if( $esmID ) {
                                wp_redirect( get_permalink( $esmID ) );
                        }else{
                                $result = \'That codeword doesn\\\'t exist.\';
                        }

                }else{
                        $result = "Please enter a codeword.";
                }
        }

        if( $result != "" ) {
                $info = \'<div class="info">\'.$result.\'</div>\';
        }

        $esm_form = \'<form method="post" action="\'.get_permalink().\'">
                <div>
                        <input type="text" name="codeword" id="esm_codeword" size="6" maxlength="6" value="\'.$form_data[\'codeword\'].\'" />
                </div>
                <div>
                        <input type="submit" value="Sumbit" name="send" id="esm_send" />
                </div>
        </form>\';

        if($sent == true) {
                return $info;
        } else {
                return $info.$esm_form;
        }
}