README.markdown

Post Merge

A WordPress plugin to merge two Posts into each other.

The plugin can be divided into three phases. In the first, Select Posts, you have to select the posts to merge. To select posts, navigate to the posts view in the admin area and use the links in the horizontal menu below a post.

The second phase, Merging, you can edit, how the merged post will look like.

Thirdly, in the Preparing stage, the plugin prepares the post to merge.

In the fourth phase, Real Merging, Post Merge will fulfill its task for real. Thus it will update the first post to be merged with the post from phase 2 and delete the other post.

About the name

There has always already been nothing to tell about it.

License

The plugin is licensed under the 2-claused BSD license. See LICENSE for details.

Extending the plugin

There are some hooks, that influence, what happens when.

Post-Merge supplies some of these hooks itself. They can be enabled as usual or disabled with remove_action or remove_filter or (later, when this is implemented) using the settings page. See below for a list.

The following filters can be hooked in a pm_merge action.

• pm_enrich_post is a filter to add additional data a post might have.

• pm_merge_fields filters fields to display when merging. You can easily remove fields not to display for merging. Note, that adding fields is not necessary Note, that it uses all fields from the post as default (after pm_enrich_post). It passes both of the posts to be merged as arguments, if you add the filter accordingly.

The following hooks can be added or removed in a pm_real_merge action.

• pm_prepare_merged_post is a filter to set specific attributes of the to be saved post.

• pm_save_post is an action to save additional fields. The old IDs are available in the old_IDs member of the post.

Internal hooks

The following filters might be used in pm_merge_fields.

• 'pm_remove_id_etc' to remove the id, the author and the date fields, so that a new post will be created with the metadata as if the current user just created the post.

Filters to be called in pm_prepare_post might be:

• With a very low priority, 'pm_prepare_basics' to save all basic fields. It will save specific metadata if it is set before. If you want to remove this, add a filter to pm_prepare_post that creates a post in the WordPress database.

The plugin might use these actions in pm_save_merged_post.

• 'pm_merge_comments' to merge comments (to be implemented).

Is there any example code on how to extend it?

Glad you asked:

# add a field to posts
function my_add_foobar($post) {
  $post->foobar = my_db_get_foobar ($post);
  return $post;
}
# remove post_author field for pages
function my_remove_author($fields, $one, $another) {
  if ($one->post_type == 'page')
    unset($fields["post_author"]);
  return $fields;
}
function my_merge() {
  add_filter('pm_enrich_post', 'my_add_foobar');
  # default priority 10
  add_filter('pm_merge_fields', 'my_remove_author', 10, 3);
}
add_action('pm_merge', 'my_merge');

function my_save_foobar($post) {
  my_db_set_foobar ($post->ID, $post->foobar);
}
function my_real_merge() {
  add_action('pm_save_merged_post','my_save_foobar');
}
add_action('pm_real_merge', 'my_real_merge');

Known bugs

There is one big one. In the Selecting Phase, you cannot use the Search Pages functionality of WordPress. This is a limitation in WordPress. See the WordPress bug for details.

Also there is this pretty non-functional page under Tools. You can click on it, and it will tell you, that you should go away. See that [WordPress bug]((https://core.trac.wordpress.org/ticket/18850).

I guess, there are plenty others. Please file a bug in the bugtracker if you find any.

There no Ajax workflow, because it has not been implemented. It should be possible using html5 history support or pretty hacky with some for now missing WordPress functionality (at least for WP3.2). Feel free to send patches.