partly responsible<\/a> for the hook being where it is — what a stroke of luck.)<\/p>\nThe action hook is ‘edit_post’. FixBack simply hooks into this, and updates the post cache by re-reading from the database. That’s all!<\/p>\n
Further thoughts<\/h2>\n
This problem may be widespread in WordPress. I know many functions in WordPress maintain internal caches that could suffer from similar problems. The FixBack plugin only fixes this one case. This functionality should be added to the core. The simplest way is to add a function that invalidates the cache for a particular post ID, and to call this function immediately after publishing the post.<\/p>\n
It would be even nicer to implement a layer (a class perhaps) that mediates all post data access — this could then maintain its cache without worrying that somebody will bypass it. Following this sort of approach throughout would be quite a big effort — WordPress 2.0?<\/p>\n
Gory details<\/h2>\n
This took me quite some time to figure out. Here I have annotated some excerpts from the WordPress source files. This may illuminate or obscure the foregoing explanations. The two colours of annotation describe the problem and the plugin solution respectively.<\/p>\n
File: wp-admin\/post.php<\/code><\/strong><\/p>\nLine 271<\/span>\r\ncase 'editpost':\r\n\t...\r\n\tThe next line calls user_can_edit_post(), which calls\r\n\tget_post(), which reads the draft post from the database\r\n\tinto $post_cache. The post status is 'draft'.<\/span>\r\n\tif (!user_can_edit_post($user_ID, $post_ID, $blog_ID))\r\n\t\tdie( __('You are not allowed to edit this post.') );\r\n\t...<\/span>\r\n\t$post_status = $_POST['post_status'];\r\n\t...<\/span>\r\nLine 364<\/span>\r\n\tThe next line updates the post in the database. This\r\n\tupdates the post slug and sets the status to 'publish'.<\/span>\r\n\t$result = $wpdb->query(\"\r\n\t\tUPDATE $wpdb->posts SET\r\n\t\t\t...<\/span>\r\n\tNow the post is published, so its slug should be set\r\n\tand its status should be set to 'publish'.<\/span>\r\nLine 430<\/span>\r\n\tif ($prev_status != 'publish' && $post_status == 'publish')\r\n\t\tWe could use this hook to refresh the cache, and\r\n\t\tthis would fix the problem with publishing drafts.\r\n\t\tBut the stale cache may have other effects, so\r\n\t\tlet's delay the refresh until the next line...<\/span>\r\n\t\tdo_action('private_to_published', $post_ID);\r\n\r\n\tHere is where we install a plugin that refreshes\r\n\t$post_cache from the database. Then in the next few\r\n\tlines, pingbacks and trackbacks will use the correct \r\n\tpermalink URL. Also, any plugins using the 'publish_post'\r\n\thook will be able to call get_permalink() with\r\n\tno problems.<\/span>\r\n\tdo_action('edit_post', $post_ID);\r\n\r\n\tif ($post_status == 'publish') {\r\n\t\tdo_action('publish_post', $post_ID);\r\n\t\tHere is the problem. The trackback and pingback\r\n\t\troutines call get_permalink(), which returns the\r\n\t\tunfancy permalink.<\/span>\r\n\t\tdo_trackbacks($post_ID);\r\n\t\tdo_enclose( $content, $post_ID );\r\n\t\tif ( get_option('default_pingback_flag') )\r\n\t\t\tpingback($content, $post_ID);\r\n\t}<\/code><\/pre>\nFile: wp-includes\/template-functions-links.php<\/code><\/strong><\/p>\nLine 25<\/span>\r\nfunction get_permalink($id = 0) {\r\n\t...\r\n\tNext line gets the post from $post_cache. When the cache was\r\n\tfilled (see above) the post slug was empty and the status was\r\n\t'draft'. Even though both are now updated in the database,\r\n\tthe cache is stale.<\/span>\r\n\t$post = & get_post($id);\r\n\t...<\/span>\r\n\tif ('' != $permalink && 'draft' != $post->post_status) {\r\n\t\t... (do the fancy permalink)<\/span>\r\n\t} else { \/\/ if they're not using the fancy permalink option\r\n\t\tWe end up here because the cached post status is\r\n\t\t'draft', though it should be 'publish'.<\/span>\r\n\t\t$permalink = get_settings('home') . '\/?p=' . $post->ID;\r\n\t\treturn apply_filters('post_link', $permalink, $post);\r\n\t}\r\n}<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"There is a bug in the way WordPress 1.5.1 handles draft posts and Advanced Editing mode. One effect of this is that pingbacks and trackbacks are sometimes sent with the wrong URL. This problem has been around for a while, but it looked a bit complicated so I figured that somebody would fix it one […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[13],"tags":[83],"class_list":["post-66","post","type-post","status-publish","format-standard","hentry","category-wordpress","tag-wordpress"],"_links":{"self":[{"href":"https:\/\/thunderguy.com\/semicolon\/wp-json\/wp\/v2\/posts\/66","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/thunderguy.com\/semicolon\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/thunderguy.com\/semicolon\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/thunderguy.com\/semicolon\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/thunderguy.com\/semicolon\/wp-json\/wp\/v2\/comments?post=66"}],"version-history":[{"count":0,"href":"https:\/\/thunderguy.com\/semicolon\/wp-json\/wp\/v2\/posts\/66\/revisions"}],"wp:attachment":[{"href":"https:\/\/thunderguy.com\/semicolon\/wp-json\/wp\/v2\/media?parent=66"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/thunderguy.com\/semicolon\/wp-json\/wp\/v2\/categories?post=66"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/thunderguy.com\/semicolon\/wp-json\/wp\/v2\/tags?post=66"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}