WordPress上传文件存放到不同目录的方法

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有时候将不同类型的文件分门别类存储，似乎比年月目录更有意义。例如幻灯片应该存储在slides目录下，下载文件应该存储在downloads文件夹下。就说幻灯片slideshow，我比较喜欢用自定义文章类型（Custom Post Type）实现，有些幻灯片脚本比较个性，不支持绝对路径，必须用相对路径，然后用base参数设置相对于哪个文件夹，这样幻灯片必须存储在某个特定的文件夹中，年月形式显然不满足要求。所以，我们需要条件化的设置上传目录。
一、为Custom Post Type设置上传目录
假设我要将所有在幻灯片类型的文章中上传的文件存储到/wp-content/uploads/slides文件夹中，将下面的代码放到主题的functions.php中即可

代码如下:

function custom_upload_directory( $uploads ) {
  $id = $_REQUEST['post_id'];
    $parent = get_post( $id )->post_parent;
  if( "post-type" == get_post_type( $id ) || "post-type" == get_post_type( $parent ) ) {
    $subdir = 'slides';
    $uploads['subdir'] = $subdir;
    $uploads['path'] = $uploads['basedir'].DIRECTORY_SEPARATOR.$subdir;
    $uploads['url'] = $uploads['baseurl'].'/'.$subdir;
  }
  return $uploads;
}
add_filter( 'upload_dir', 'custom_upload_directory' );

将post-type替换成自己的自定义文章类型名称，将你要创建的子目录赋值给$subdir。
二、将文件保存到插件目录
下面的代码要用在插件中，文件会保存到插件目录下的uploads文件夹下。

代码如下:

/**
 * Change Upload Directory for Custom Post-Type
 *
 * This will change the upload directory for a custom post-type. Attachments will
 * now be uploaded to an "uploads" directory within the folder of your plugin. Make
 * sure you swap out "post-type" in the if-statement with the appropriate value...
 */
function custom_upload_directory( $args ) {
  $id = $_REQUEST['post_id'];
  $parent = get_post( $id )->post_parent;
  // Check the post-type of the current post
  if( "post-type" == get_post_type( $id ) || "post-type" == get_post_type( $parent ) ) {
    $args['path'] = plugin_dir_path(__FILE__) . "uploads";
    $args['url']  = plugin_dir_url(__FILE__) . "uploads";
    $args['basedir'] = plugin_dir_path(__FILE__) . "uploads";
    $args['baseurl'] = plugin_dir_url(__FILE__) . "uploads";
  }
  return $args;
}
add_filter( 'upload_dir', 'custom_upload_directory' );

如果要以年月形式保存，修改一下代码即可

代码如下:

$args['path'] = plugin_dir_path(__FILE__) . "uploads" . $args['subdir'];
$args['url']  = plugin_dir_url(__FILE__) . "uploads" . $args['subdir'];

三、为后台管理页面设定upload_dir
用wp_editor在后台管理页面（比如用add_menu_page创建的页面）创建一个媒体上传功能，希望所有从该页面上传的文件都保存到wp-content/uploads/myfolder目录下。
由 于ajax上传是直接调用wp-admin/async_upload.php文件，只能通过post_id获取post信息，而后台管理页面并非 post，所以判断什么时候应该更改upload_dir有些麻烦。此时，可以用采用判断页面referer的方法,用wp_get_referer() 函数获取引荐url，如果正好与我们的option page url想等，就更该目录。

代码如下:

function custom_upload_directory( $uploads ) {
   if( wp_get_referer() == 'http://domain.com/wp-admin/admin.php?page=myoptionpage'){
    $subdir = 'myfolder';
    $uploads['subdir'] = $subdir;
    $uploads['path'] = $uploads['basedir'].DIRECTORY_SEPARATOR.$subdir;
    $uploads['url'] = $uploads['baseurl'].'/'.$subdir;
   }
   return $uploads;
}
add_filter( 'upload_dir', 'custom_upload_directory' );

四、参考信息
filter:upload_dir是在wp_upload_dir()函数中调用的
$upload_dir = wp_upload_dir();

代码如下:

$upload_dir now contains something like the following (if successful)
Array (
  [path] => C:\path\to\wordpress\wp-content\uploads\2010\05
  [url] => http://example.com/wp-content/uploads/2010/05
  [subdir] => /2010/05
  [basedir] => C:\path\to\wordpress\wp-content\uploads
  [baseurl] => http://example.com/wp-content/uploads
  [error] =>
)