Dynamic Tilestache Layers

[ckotil]

Is it possible to pass in arguments to Tilestache? In my current configuration I have a LOT of layers for serving vector data. Each layer only differs slightly in the SQL query where it selects a different layer_id. My config could be greatly simplified into a single layer by having the ability to pass in a !layer_id! argument in the URL request; /vector_data/x/y/z.json?layer_id=52 . I've seen the variable !bbox! which is an argument that can be passed in and parsed by Tilestache, so Im thinking passing in another argument may be possibe. But so far I have not been able to find any examples or found anyone else doing this.

There have been a couple of posts I've stumbled onto that sound close to what I want to do.

https://groups.google.com/forum/#!topic/tilestache/o-xpJ-3FZOE

http://stackoverflow.com/questions/11751628/tilestache-provider-layer-object-can-the-referring-url-be-obtained

Both hint at using a alternate WSGI server, but Im not sure how to go about doing that.

Any ideas?

Thanks,

--Chad

[ckotil]

After thinking about this more, perhaps being able to pass in dynamic arguments to modify the query isn't the best thing for tilestache. It effectively breaks the cache.

However I could argue that as long as the number variables were small that the cache could still be used.

For now Im testing a few different methods.

1. A couple thousand layers

2. Return all of the data at once in a handful of layers and use JS to display/hide the data as needed.

[Olivier Ceyral]

So, I had this problems a few months back for a project.

I queried my layer with a basic /tiles/layer_id/x/y/z.json url, but I wanted to be able to add and remove layers on the fly, so I couldn't have a gigantic static config file.

The solution I found was to use TileStache.Goodies.ExternalConfigServer as a base, and then modify it to query the database instead of a remote configuration server. It's fairly easy to do and worked quite well. It also doesn't breaks the cache, the tiles will be cached as different layers anyway, so you'll have a directory for each layer e.g. /tiles/layer1/..., /tiles/layer2/..., etc... With thousands of layers though, you might want to look at filesystem restrictions regarding the number of files in a folder.

[Alex King]

Hi Oceyral,

I know it's been several years, but would you by chance have an example of how you changed your ExternalConfigServer file? I'm very interested in your solution.

Thanks!
Alex