Rails - Aug 2010 - 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''

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On Mon, Aug 2, 2010 at 2:26 PM, wprater
<mc.willprater-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 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 Bates 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

>
> 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''
>
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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

On Aug 3, 8:01 am, Conrad Taylor
<conra...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> On Mon, Aug 2, 2010 at 2:26 PM, wprater
<mc.willpra...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 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 Bates 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
>
>
>
> > 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''
>
> > --
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Thanks, that worked for me.  I''m not able to upgrade to RC1 quite yet.

Cheers,

-Will


On Aug 3, 3:20 am, Huet <h...-j1senl6PQQNhbmWW9KSYcQ@public.gmane.org>
wrote:
> 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
>
> On Aug 3, 8:01 am, Conrad Taylor
<conra...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
>
>
> > On Mon, Aug 2, 2010 at 2:26 PM, wprater
<mc.willpra...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > > Here is my model and an attempt to convert to json.  Whether
there is
> > > data returned or not, acircularreference 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 Bates 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
>
> > > 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''
>
> > > --
> > > You received this message because you are subscribed to the
Google Groups
> > > "Ruby on Rails: Talk" group.
> > > To post to this group, send email to
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> > >
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e@googlegroups.com>
> > > .
> > > For more options, visit this group at
> > >http://groups.google.com/group/rubyonrails-talk?hl=en.
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