Controller::Rewrite

The Controller::Rewrite layer can match and rewrite requests before they processed. This allows you to handle URLs like /post/15/view or /blog/123-pictures-of-my-cat easily. The basic rewrite operation is to extract some part of the path and optionally executes a block. That means that the path is modified before being passed on to the next layer in the controller, and controller instance variables may be set.

Regular Expressions

In your controller.rb:

prepend Rewrite, Actions

rewrite.extract_prefix permalink: /(?<id>\d+)-(?<title>.*)/ do |request, path, match|
	# The rewrite matched, but there was no valid post, so we fail:
	fail! unless @post = Post.find(@permalink[:id])
	
	# If the path matched, but there was no suffix, we make it default to the post action:
	if match.post_match.empty?
		match.post_match.components << "post"
	end
end

on 'post' do
	# You can do further processing here.
	fail! unless @post.published?
	
	@comments = @post.comments.first(5)
end

on 'edit' do
	# You can do further processing here.
	fail! unless @current_user&.editor?
end

In your post.xnode, as an example:

<content:page>
	<content:heading>Post #{attributes[:permalink][:id]} about #{attributes[:permalink][:title]}</content:heading>
	
	<p>#{attributes[:post].content}</p>
</content:page>

Keep in mind, that URLs like /123-pictures-of-my-cat/edit will work as expected, and hit the edit action of the controller.

Restful Resources

Similar to the above, if we were solely interested in IDs, we could do the following:

prepend Rewrite, Actions

rewrite.extract_prefix post_id: Integer do |request, path, match|
	# The rewrite matched, but there was no valid post, so we fail:
	fail! unless @post = Post.find(@post_id)
	
	# If the path matched, but there was no suffix, we make it default to the post action:
	if match.post_match.empty?
		match.post_match.components << "post"
	end
end

This will only match complete integers. Assuming this code is in /blog/controller.rb, it would match something like /blog/123/view and assign Integer("123") to @post_id.

Matching.. other things

It’s possible to match using Integer, Float, String, and you can provide your own class which will be instantiated. If it doesn’t match, raise an exception and the rewrite rule will fail.