如何重构我的Sinatra应用程序？

Question

I've just started writing a reasonably straightforward site using sinatra. My problem is that I wanted to refactor the main app.rb file but am getting errors trying to access the url params.

In my get '/' action, Sinatra's looking at which params are set and then needs to do a few different things depending on what's in the url. Something like this.

class App < Sinatra::Application
  ...
  get '/' do
    if params['code1']
      @network = 'code1'
      mode code here
    elsif params['called'] && params['mac']
      @network = 'code2'
      mode code here
    elsif params['code3']
      @network = 'code3'
      mode code here
    end  
  end      

The problem is that I need to require a file that also uses the params.

I've put the following in the above code:

require File.dirname(__FILE__) + '/lib/networks/code1.rb'

Where code1.rb includes:

class App < Sinatra::Application
  if params['login']  # == 'login'
    pass = 'uampass'
  elsif
  ...

But that gives me the following error:

undefined local variable or method `params' for main:Object

How can I refactor this without causing an error

Answer 1

As far as i know you can't use two (or more) Sinatra applications in, well one application. Since both files define a Sinatra::Application descendant this isn't possible.

Also if you want to use values from the params -hash you should define helper methods Helper Documentation , which you call when processing the route, or you just create Class which has class or instance methods which take params-values as parameters. Actually calling params from another file/class doesn't seem like good practice.

To put this in context: Sinatra applications are organised as handlers. The Sinatra::Application descendant is something like the main handler which uses support methods(helpers and instance methods of the Sinatra::Application descendant) or support Classes, which are usually defined in other files, but do not descend from Sinatra::Application .

To make this a little bit more clearly:

Your main Sinatra file:

require_relative 'another_file.rb'
class App < Sinatra::Application
  # ...
  @a_handler = MyHandler.new
  get '/' do

    if params['something'] == 'wanted_value'
      @a_handler.handle_it(params)
    end

end

Another file ('another_file.rb'):

class MyHandler
  def initialize
    @an_instance_variable = 'foobar'
  end
  def handle_it(params_hash)
    if params_hash['login']  # == 'login'
      pass = 'uampass'
    elsif
     # ...
    end
    # ...
    # do some stuff
    # ....
    return pass
  end
end

Actual code would of course depend on the real problem you're trying to solve, so if you would elaborate i could be more precise...

Answer 2

The error message contains everything you need to know, and it's nothing to do with Sinatra.

You are requiring code1.rb, which contains this (slightly edited so it will run):

require 'sinatra'

class App < Sinatra::Application
  if params['login']  # == 'login'
    pass = 'uampass'
  end
end

Ruby evaluates code as it encounters it. In this case, you've required 'code1.rb', so it evaluates the code in that file. It encounters 'params' and asks "is there a local variable or method with that name?". There isn't, so it fails as you've seen. Open an irb session and check it out.

Class definitions in ruby are just an expression with a scope.

In relation to Sinatra: params is available in the block that a route declaration takes.

I'd recommend reading Sinatra: Up and Running , which explains some of the 'magic' that is going on (a good companion to the Sinatra Book ).