Rails3-beta4: Calling to_json on an ActiveRecord::Relation causes an error

Here is my model and an attempt to convert to json. Whether there is
data returned or not, a circular reference error is thrown. How can I
avoid this?

ruby-1.8.7-p249 > PayPeriod
=> PayPeriod(id: integer, start_date: date, end_date: date, pay_date:
date)
ruby-1.8.7-p249 > PayPeriod.where(‘end_date < ?’, Time.now)
=> []
ruby-1.8.7-p249 > PayPeriod.where(‘end_date < ?’, Time.now).to_json
ActiveSupport::JSON::Encoding::CircularReferenceError: object
references itself
from /Users/wprater/.rvm/gems/ruby-1.8.7-p249/gems/
activesupport-3.0.0.beta4/lib/active_support/json/encoding.rb:59:in
`check_for_circular_references’

On Mon, Aug 2, 2010 at 2:26 PM, wprater [email protected] wrote:

Here is my model and an attempt to convert to json. Whether there is
data returned or not, a circular reference error is thrown. How can I
avoid this?

wprater, I would recommend trying Rails 3 RC by doing the following:

gem install rails --pre

Also, if you don’t have a requirement to use Ruby 1.8.7, I would
recommend
using Ruby 1.9.2 RC2 by doing the following:

rvm install 1.9.2

Ryan B. recently added the following screencast which covers the
installation
of both Rails 3 and Ruby 1.9.2.

http://media.railscasts.com/videos/225_upgrading_to_rails_3_part_1.mov

Good luck,

-Conrad

Thanks, that worked for me. I’m not able to upgrade to RC1 quite yet.

Cheers,

-Will

Hi All,

I have had this problem with Rails 3 and 1.9.1. The fix for this error
is to add to_a to the json call.

render :json => {:top => @top.to_a.as_json(:only => [:id, :title ] ) }

Hope this helps.

Huet

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