Re: Using Rack Middlware to filter parameters

["Iñaki Baz Castillo" <ibc@aliax.net>]

El Jueves, 5 de Noviembre de 2009, RobL escribió:
> Hi there,
> 
> I wanted to ask if anyone could point me in the direction of some code
> examples where you can use Rack Middleware to filter incoming
> parameters.

> But as a very tivial example I want be able to do something like
> 
> module Rack
>   class Myfilter
>     def initialize(app)
>       @app = app
>     end
> 
>     def call(env)
>        request = Rack::Request.new(env)
>        request.params.delete('someparam')
>        # but at this point I want/need to modify env
>        @app.call(env)
>     end
>   end
> end
> 
> I'm not sure how I'd then get the modified env back, do you have to
> literally modify something like env['query_string'], also at this
> point the content length would be different so I'd have to update that
> also.

Do you mean parameters in the request URI? or in the body? in the first case 
the content-length should not be modified.

 
> Most of the applications I've seen are an endpoint and an app in
> itself than sitting in the middle of the incoming request, and I'm yet
> to find an example of modifying the incoming params.

I expect that Rack is not designed for that, as changing the request is not a 
very common usage (IMHO).

-- 
Iñaki Baz Castillo <ibc@aliax.net>