How to extract URL parameters from a URL with Ruby or Rails?

I found myself needing the same thing for a recent project. Building on Levi's solution, here's a cleaner and faster method:

Rack::Utils.parse_nested_query 'param1=value1&param2=value2&param3=value3'
# => {"param1"=>"value1", "param2"=>"value2", "param3"=>"value3"}

Just Improved with Levi answer above -

Rack::Utils.parse_query URI("http://example.com?par=hello&par2=bye").query

For a string like above url, it will return

{ "par" => "hello", "par2" => "bye" } 

For a pure Ruby solution combine URI.parse with CGI.parse (this can be used even if Rails/Rack etc. are not required):

CGI.parse(URI.parse(url).query) 
# =>  {"name1" => ["value1"], "name2" => ["value1", "value2", ...] }

There more than one ways, to solve your problem. Others has shown you the some tricks. I know another trick. Here is my try :-

require 'uri'
url = "http://www.example.com/something?param1=value1&param2=value2&param3=value3"
uri = URI(url)
# => #<URI::HTTP:0x89e4898 URL:http://www.example.com/something?param1=value1&param2=value2&param3=value3>
URI::decode_www_form(uri.query).to_h # if you are in 2.1 or later version of Ruby
# => {"param1"=>"value1", "param2"=>"value2", "param3"=>"value3"}
Hash[URI::decode_www_form(uri.query)] # if you are below 2.1 version of Ruby
# => {"param1"=>"value1", "param2"=>"value2", "param3"=>"value3"}

Read the method docomentation of ::decode_www_form.

Check out the addressable gem - a popular replacement for Ruby's URI module that makes query parsing easy:

require "addressable/uri"
uri = Addressable::URI.parse("http://www.example.com/something?param1=value1&param2=value2&param3=value3")
uri.query_values['param1']
=> 'value1'

(It also apparently handles param encoding/decoding, unlike URI)

Using CGI might be an outdated approach with Ruby 2.7/3.

Here's a neat way to do this with URI:

uri = URI.parse 'https://duckduckgo.com/?q=ruby+programming+language'
params = Hash[URI.decode_www_form uri.query]
# => {"q"=>"ruby programming language"} 

you can also use this method

require 'uri'
require 'cgi'
uri = URI("https://example.com/?query=1&q=2&query=5")
a = CGI::parse(uri.query)
puts a                   #=> {"query"=>["1", "5"], "q"=>["2"]}
puts a["query"].to_s     #=> ["1", "5"]
puts a["query"][0]       #=>  1
puts a["query"][1]       #=>  5
puts a["q"][0]           #=>  2

its safe and much easier

Sadly both the URI and addressable libraries break when attempting to extract query params from buggy URLs. E.g. this breaks both:

http://localhost:4300/webapp/foo/#//controller/action?account=001-001-111&email=john%40email.com

Building on Arthur / Levi's solution, with url.split("?").try(:last) you can grab just the query param portion of the URL, and use Rack::Utils.parse_nested_query to parse that string of parameters into a hash.

Or in full:

Rack::Utils.parse_nested_query(url.split("?").try(:last))

returning in my example:

{"account": "001-001-111", "email": "[email protected]"}

The above answers are very well written and they serve the purpose, however I tried some query manipulation and wanted to share here. So, here is my take:

   URI("http://example.com?par=hello&par2=bye").query.split('&').map { |param| {query_param: param.split('=')[0] , value: param.split('=')[1]}  }

It serves the purpose and return an array of objects for each query param. Having said that, please keep in mind the COC principle of ROR.