Add Parse Query Params From A URL as a rails til

rails/parse-query-params-from-a-url.md

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+# Parse Query Params From A URL
+
+For all of the conveniences that Ruby and Rails affords a developer through
+their expansive APIs, I am always surprised that it is hard to inspect the
+query params in a URL.
+
+Let's take a URL and walk through the steps it takes to pull out the value of a
+query param.
+
+Here's a URL:
+
+```ruby
+url = "https://example.com?taco=bell&taco_count=3"
+=> "https://example.com?taco=bell&taco_count=3"
+```
+
+Let's parse the URL with `URI`:
+
+```ruby
+> URI(url)
+=> #<URI::HTTPS https://example.com?taco=bell&taco_count=3>
+```
+
+Then grab the `query` part of that `URI`:
+
+```ruby
+> URI(url).query
+=> "taco=bell&taco_count=3"
+```
+
+This is an unparsed string. In a Rails context, this can be parsed with
+`Rack::Utils.parse_nested_query`:
+
+```ruby
+> query_params = Rack::Utils.parse_nested_query(URI(url).query)
+=> {"taco"=>"bell", "taco_count"=>"3"}
+```
+
+And now we have a hash of values we can inspect:
+
+```ruby
+> query_params["taco_count"]
+=> "3"
+```
+
+Be sure to do _string_ and not _symbol_ hash access here.
+
+These steps can be wrapped up into a method:
+
+```ruby
+module UrlHelpers
+  def query_params(url)
+    unparsed_query_params = URI(url).query
+    Rack::Utils.parse_nested_query(unparsed_query_params)
+  end
+end
+```
+
+[source](https://stackoverflow.com/a/3218018/535590)