Rails Routes: Programmatically extract params from a URL

Question

I need to programmatically extract the params from a URL, ie the hash that the controller would receive if the URL was called. This is not happening inside the controller, it's for an introspection tool, so the controller is never run. I want to predict what would happen if the controller was run, hopefully using the same API Rails itself is using.

For example, given a Rails route /blogs/:id and a URL query of /blogs/123?published=true, I want to extract { id: 123, published: true }.

Using Rails.application.routes.recognize_path, I can get the id in this example as it's part of the route pattern, but not the extra CGI param (published). I could manually add those, but I'd like to know if there's a proper API for this.

No, I know the basic of params but this needs to be done programmatically. Updated the question to clarify that. — mahemoff
– mahemoff, Commented Jan 7, 2015 at 12:08
based on your comment on an answer below? are you looking to run this as a Rack App? Does it need to sit in front of the controller? will it be run in production? Or is it more simulating / gathering metadata about that app? — Doon
– Doon, Commented Jan 7, 2015 at 12:51
Just gathering metadata. It's primarily needed for a batch controller that lets callers multiplex a bunch of calls together. — mahemoff
– mahemoff, Commented Jan 7, 2015 at 18:28

Harsh Gupta · Accepted Answer · 2015-01-07 19:27:12Z

3

You can parse the URL, read the query string and convert them to hash.

u = URI.parse("http://localhost:3000/blogs/213?published=true")
cgi_params = u.query.split('&').map { |e| e.split('=') }.to_h

Merge them with params that you got using Rails.application.routes.recognize_path

answered Jan 7, 2015 at 19:27

Harsh Gupta

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Simone Carletti · Accepted Answer · 2015-01-07 12:01:29Z

1

The params Hash contains all the route parameters, including the query parameters.

# Given /blogs/123?published=true
def action
  params[:id] # => 123
  params[:published] # => "true"
end

answered Jan 7, 2015 at 12:01

Simone Carletti

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1 Comment

mahemoff Over a year ago

Thanks but I'm looking for an introspection tool where the controller isn't actually run.

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