Hi devs,
I wanted to rewrite URL beyond that what's currently possible with the
CouchDB rewrite. I especially had in mind URLs where that need to
conform to a certain standard and where you need a proxy in front of it
to serve them up in that specific way. I have two use cases in mind.
First one with for wikis with subpages. You might want to have URLs like:
http://example.com/wiki/apache-projects/couchdb/info
as opposed to
http://example.com/wiki/apache-projects%2fcouchd%2f/info
While I tried this with JChris' Pages wiki, I found out that if a _show
function is used, you can also have such URLs with the current rewriter
(though directly accessing the documents with non URL encoded slashes
won't be possible).
My second one is a TMS tilecache [1]. Those who don't know what it is,
it's for serving up map tiles like Google or OpenStreetmap does. I would
create a document per tile and attach the file to it. My URL would look
like this (where "tile" is the attachement):
http://example.com/tilecache/3-5-2/tile
But I'd need an URL like
http://example.com/tilecache/tiles/3/5/2.png
(resp.
http://example.com/tilecache/_design/tilecache/_rewrite/tiles/6/9/9.png)
My modification to the rewriter allows you to replace substrings with
other ones. Here's the rewriter rule for this example:
{
"from" : "/tiles/<x>/<y>/<z>.png",
"to" : "..\\/..\\/:x/:y/:z/tile",
"replace": {
"old": "/",
"new": "-",
"limit": -1
}
}
It replaces all occurences of "/" with "-" on the "to"-path. Two slashes
("\\") escape a character, so it won't be replaced. The "limit"
parameter specifies how many occurences should be replaced. It could be
either positive, then it will just count how often a string was already
replaced and stop at the limit. If "limit" is negative, it will count
from the back. This is especially useful if you want to replace slashes
and know how many slashes the attachment has, but not how many the
document has.
The changes are available here:
https://github.com/vmx/couchdb/commit/889024df75892fb46a1e513e54466fa5bbe69e49
Comments please :)
[1] http://wiki.osgeo.org/wiki/Tile_Map_Service_Specification
Cheers,
Volker
