wpxml_parser
WordPress (version 3.x and I think there's a plugin for 2.x) can export xml with all your blog posts, comments, etc. This tool can parse the xml file and give you a convenient access to all your posts, comments, categories, etc in a ruby script that you have to write.
The cool thing is — you don't even need to have access to your own WordPress database, all you need is to download the xml file from your admin panel.
Install
gem install wpxml_parser
Usage
require 'wpxml_parser'
include WpxmlParser
# Blog
blog = Blog.new('dump_of_your_blog.xml')
blog.posts.size # => 51
post = blog.posts.first # => <Post>
# Post
post.title # => "Title of your post"
post.categories # => ["ruby", "rails"]
post.date # => <Time>
post.slug # => "title-of-your-post"
post.body # => "...shitload of text..."
post.post_id # => 27
# Comments
post.comments # => [<Comment>, <Comment>, ...]
comment = post.comments.first
comment.author # => 'dude'
comment.date # => <Time>
# Comments have parent and children
comment.parent_id # => 32
comment.parent # => <Comment>
comment.children # => [<Comment>, <Comment>]
# Conveniences
# You can quickly find a post or a comment by post_id or comment_id respectively
blog.find_post(27) # => <Post>
post.find_comment(32) # => <Comment>
# For more info and more accessible properties check out the source code, it's pretty straightforward.
A note on posts
Currently only published posts are included. Drafts, private, etc are skipped. This was done on purpose, since I didn't really use those wordpress features.
A note on comments
Currently only approved comments are included. This was done on purpose, since I didn't need spam.