I am writing a web-based dev-console for Rails development. In one of my controller actions, I am calling Rake, but I am unable to capture any of the output that Rake generates. For example, here is some sample code, from the controller:

require 'rake'
require 'rake/rdoctask'
require 'rake/testtask'
require 'tasks/rails'
require 'stringio'

...

def show_routes

  @results = capture_stdout { Rake.tasks['routes'].invoke }

  # @results is nil -- the capture_stdout doesn't catpure anything that Rake generates

end

def capture_stdout
  s = StringIO.new
  $stdout = s
  yield
  s.string
ensure
  $stdout = STDOUT
end

Does anybody know why I can't capture the Rake output? I've tried going through the Rake source, and I can't see where it fires a new process or anything, so I think I ought to be able to do this.

Many thanks! Adrian

I have since discovered the correct way to call Rake from inside Ruby that works much better:

Rake.application['db:migrate:redo'].reenable
Rake.application['db:migrate:redo'].invoke

Strangely, some rake tasks work perfectly now (routes), some capture the output the first time the run and after that are always blank (db:migrate:redo) and some don't seem to ever capture output (test). Odd.