主代码请检查此块后的辅助代码

/*
 * Prevent Duplicated Titles
 *
 */

if( is_admin() ) // check if we are in the administrative area
{
    add_action( \'save_post\', \'wpse_54258_check_for_duplicate_title\', 11, 2 );
    add_action( \'admin_head-post.php\', \'wpse_54258_check_for_notice\' );
}

/*
 * Checks for more than one post with the same title
 *
 * Adds filter redirect_post_location if duplicate title found
 *
 */

function wpse_54258_check_for_duplicate_title( $post_id, $post )
{
    // HERE, FURTHER FILTERING CAN BE DONE, RESTRICT USERS, POST_TYPES, ETC
    if ( 
        ( defined( \'DOING_AUTOSAVE\' ) && DOING_AUTOSAVE )
        or ! current_user_can( \'edit_post\', $post_id )
        or wp_is_post_revision( $post )
        // ADD OTHER FILTERS, LIKE post_type
    )
    { // Noting to do.
        return;
    }

    $termid = get_post_meta($post_id, \'_is_dup\', true);
    if ( \'\' != $termid ) 
    {
        // it\'s a new record
        $count_dups = 0;
        update_post_meta($post_id, \'_is_dup\', \'new-post-check\');
    } 
    else 
    {
        $count_dups = 1;
    }
    
    // NO CHECKING IS BEING DONE REGARDING UPPER AND LOWERCASES, NOR FOR HTML TAGS
    global $wpdb;
    $title_exists = $wpdb->get_results( $wpdb->prepare( "SELECT ID FROM $wpdb->posts WHERE post_title = \'$post->post_title\' AND post_status = \'publish\'") );

    if( count($title_exists) > $count_dups ) 
        add_filter(\'redirect_post_location\',\'wpse_54258_add_error_query_var\');
}


/*
 * Removes the previous applied filter and adds error var to the redirect
 *
 */

function wpse_54258_add_error_query_var( $loc ) 
{
    remove_filter( \'redirect_post_location\',\'wpse_54258_add_error_query_var\' );
    return add_query_arg( \'duplicated_title\', 123, $loc );
}


/*
 * Error checking after saving the post
 *
 */

function wpse_54258_check_for_notice()
{
    if( isset( $_GET[\'duplicated_title\'] ) )
        add_action( \'admin_notices\', \'wpse_54258_display_error_message\' );
}

/*
 * Actual error message for duplicated post titles
 *
 */
function wpse_54258_display_error_message()
{ ?>
    <div class="error fade">ERROR</div>
    <?php
    remove_action( \'admin_notices\', \'wpse_54258_display_error_message\' );
}

用于检查是否正在创建新帖子/页面的方法需要post_meta 这必须应用于以前的所有帖子/页面。

/*
 * Update ALL PUBLISHED posts and pages with the controller post_meta required by the main code
 *
 * Important: Run Only Once 
 * -> Paste in functions.php
 * -> Remove the comment to add_action
 * -> Visit any administrative page
 * -> Delete or disable this code
 * 
 */
//add_action(\'admin_init\',\'wpse_54258_run_only_once\');
function wpse_54258_run_only_once()
{   
    global $wpdb;
    $allposts = $wpdb->get_results( "SELECT ID FROM $wpdb->posts WHERE post_status = \'published\'" );
    foreach( $allposts as $pt )
    {
        update_post_meta( $pt->ID, \'_is_dup\', \'new-post-check\');
    }
}

这个答案是通过以下方式组合而成的：

托肖对这个问题的回答：Take excerpt of the content of the post and send it as the title to create new post

Otto\'s solution 在Ana Ban提供的链接中，回答如下：Passing error/warning messages from a meta box to "admin_notices"Check for update vs new post on save_post actionpost-new.php 死亡医生对另一个问题的回答是：Why does save_post action fire when creating a new post?