WordPress上传图片自动添加Alt和图像描述

将下面的代码添加到当前主题函数模板functions.php中：

add_action( 'add_attachment', 'my_set_image_meta_upon_image_upload' ); 
function my_set_image_meta_upon_image_upload( $post_ID ) {
  	// Check if uploaded file is an image, else do nothing
  	if ( wp_attachment_is_image( $post_ID ) ) {
  		$my_image_title = get_post( $post_ID )->post_title;
  		// Sanitize the title:  remove hyphens, underscores & extra spaces:
 		$my_image_title = preg_replace( '%s*[-_s]+s*%', ' ',  $my_image_title );
  		// Sanitize the title:  capitalize first letter of every word (other letters lower case):
 		$my_image_title = ucwords( strtolower( $my_image_title ) );
  		// Create an array with the image meta (Title, Caption, Description) to be updated
 		// Note:  comment out the Excerpt/Caption or Content/Description lines if not needed
 		$my_image_meta = array(
 			'ID'		=> $post_ID,
			// Specify the image (ID) to be updated
 			'post_title'	=> $my_image_title,
		// Set image Title to sanitized title
 			'post_excerpt'	=> $my_image_title,
		// Set image Caption (Excerpt) to sanitized title
 			'post_content'	=> $my_image_title,
		// Set image Description (Content) to sanitized title
 		);
  		// Set the image Alt-Text
 		update_post_meta( $post_ID, '_wp_attachment_image_alt', $my_image_title );
  		// Set the image meta (e.g. Title, Excerpt, Content)
 		wp_update_post( $my_image_meta );  	}  }

代码可以过滤掉图片名称中的空格等多余元素，对之前上传的图片无效。