Question

I’m positive this is a dupe, but I couldn’t find the original.

Given a GET-style string like foo=bar&x[0]=baz, how can I decode this into a params-like array in a Rails app?

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Updated to add: Note that CGI.parse seems to do much less than whatever magic Rails does:

1.9.3p194 :006 > CGI::parse 'foo=bar&x[foo][bar]=baz'
 => {"foo"=>["bar"], "x[foo][bar]"=>["baz"]} 

CGI.parse didn’t unpack the nested objects into a mult-level hash. In Rails, at some level, this is actually examined.

Answer 1

For nested queries, Rails uses Racks’ parameter parser Rack::Utils.parse_nested_query:

Rack::Utils.parse_nested_query 'foo=bar&x[foo][bar]=baz'
 => {"foo"=>"bar", "x"=>{"foo"=>{"bar"=>"baz"}}}