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I'm Jason, a web applications developer in the San Francisco Bay area.

Building a Query String from a Hash with Rails 3

I have a model has a method that generates and stores a cached link to it’s own view for use in mailers. Under Rails 2 the method which generated this link created the beginning of the URL based on the owner of the object (this is a multi-domain system I’m working on), however it required that a hash of parameters be included in the link.

Under Rails 2 the ‘options’ hash would be passed to build_query_string inside of my method like so:

params =

Under Rails 3 I receive this error:

wrong number of arguments (0 for 7)

It turns out that under Rails 3 the Hash library includes a to_query method.

irb(main):001:0> h = {:blah => '1', :blah2 => '2'}
=> {:blah=>"1", :blah2=>"2"}

irb(main):002:0> h.to_query
=> "blah2=2&blah=1"

Thanks to mjrussel for posting this on StackOverflow.