Yii url rules - optional parameters

Assume we have an action "articles/get" which accepts optional parameters and we want to setup following URLs:

articles/[article id or name]
articles/[article id or name]/draft
articles/[article id or name]/revisions/99
articles/[article id or name]/revisions/98/draft
articles/revisions/[revision id]
articles/revisions/[revision id]/draft

We have a list of articles and each article has several revisions. Also each revision can have draft and published version.

In the code we have a single 'article/get' action which allows us to get specific article (last revision) by name ('GET articles/my-article') or id ('GET articles/33').

Using additional parameters we can get last revision draft ('GET articles/33/draft'), get specific revision ('GET articles/33/revisions/99') or get article using revision ID only ('GET articles/revisions/99').

Now we can setup URL rules for these routes like this:

//- articles/revisions/98/draft
array('article/get',
'pattern' => 'articles/revisions/<revision:\d+>/<version:published|draft>',
'verb' => 'GET'
),
//- articles/revisions/99
array('article/get',
'pattern' => 'articles/revisions/<revision:\d+>',
'verb' => 'GET'
),
//- articles/77/revisions/99/draft
array('article/get',
'pattern' => 'articles/<article:[\w\d\.]+>/revisions/<revision:\d+>/<version:published|draft>',
'verb' => 'GET'
),
//- articles/77/revisions/99
array('article/get',
'pattern' => 'articles/<article:[\w\d\.]+>/revisions/<revision:\d+>',
'verb' => 'GET'
),
//- articles/77/draft
array('article/get',
'pattern' => 'articles/<revision:[\w\d\.]+>/<version:published|draft>',
'verb' => 'GET'
),
// articles/77 (or articles/[name])
array('articles/get',
'pattern' => 'article/<article:[\w\d\.]+>',
'verb' => 'GET'
),

But there is much better option. We can describe this a single URL route with optional parameters (regexp groups with trailing question mark do the trick):

array('app/get',
'pattern' => 'apps(/<app:[\w\d\.]+>)?(/updates/<update:\d+>)?(/<revision:published|draft>)?',
'verb' => 'GET'
),

Optional parameters at the end

The special case is when we need to allow any number of additional parameters at the end of the URL. This case is supported by URL manager:

If a pattern ends with '/*', it means additional GET parameters may be appended to the path info part of the URL; otherwise, the GET parameters can only appear in the query string part.