Hi all,
The setup:
I''ve got a Candidate model, and it has two associations like:
has_many :next_tasks, :class_name => ''Task'', :foreign_key
=>
''candidate_id'', :conditions => [''start_time >
now() and not deleted 0''], :order => ''start_time''
has_many :previous_tasks, :class_name => ''Task'',
:foreign_key =>
''candidate_id'', :conditions => [''start_time <
now() and not deleted 0''], :order => ''start_time
desc''
I have a controller which is using will_paginate, which at some point is
using ActiveRecord to get a count, and it''s eager loading both of these
associations:
:include => [:status, :position, :user, { :previous_tasks => :user },
{:next_tasks => :user}, :hiring_manager]
The problem:
I''m getting an error like:
Column ''start_time'' in on clause is ambiguous ...
The two relevant areas of the clause are:
LEFT OUTER JOIN `tasks` ON tasks.candidate_id = candidates.id AND
start_time < now() and not deleted = 0
and
LEFT OUTER JOIN `tasks` next_tasks_candidates ON
next_tasks_candidates.candidate_id = candidates.id AND start_time >
now() and not deleted = 0
So, AR is smart enough to join ''tasks'' as
next_tasks_candidates, but not
to append that join name to the conditions.
This seems (notice, just seems... I don''t pretend to be a Rails expert,
demanding that this is a problem with Rails and not my code) to be a
problem with AR and doing a count on a query that is eager loading two
associations which have conditions with the same variable names in them.
Anyone have any thoughts on what I can do to fix this?
Thanks,
Luke
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Frederick Cheung
2008-Sep-04 07:46 UTC
Re: Eager loading, like column names, and conditions
On 4 Sep 2008, at 07:01, Luke Ivers wrote:> > Hi all, > > The setup: > I''ve got a Candidate model, and it has two associations like: > has_many :next_tasks, :class_name => ''Task'', :foreign_key => > ''candidate_id'', :conditions => [''start_time > now() and not deleted > 0''], :order => ''start_time'' > has_many :previous_tasks, :class_name => ''Task'', :foreign_key => > ''candidate_id'', :conditions => [''start_time < now() and not deleted > 0''], :order => ''start_time desc'' > > I have a controller which is using will_paginate, which at some > point is > using ActiveRecord to get a count, and it''s eager loading both of > these > associations: > :include => [:status, :position, :user, { :previous_tasks => :user }, > {:next_tasks => :user}, :hiring_manager] > > The problem: > > I''m getting an error like: > Column ''start_time'' in on clause is ambiguous ... > The two relevant areas of the clause are: > LEFT OUTER JOIN `tasks` ON tasks.candidate_id = candidates.id AND > start_time < now() and not deleted = 0 > and > LEFT OUTER JOIN `tasks` next_tasks_candidates ON > next_tasks_candidates.candidate_id = candidates.id AND start_time > > now() and not deleted = 0 > > > So, AR is smart enough to join ''tasks'' as next_tasks_candidates, but > not > to append that join name to the conditions. > > This seems (notice, just seems... I don''t pretend to be a Rails > expert, > demanding that this is a problem with Rails and not my code) to be a > problem with AR and doing a count on a query that is eager loading two > associations which have conditions with the same variable names in > them. > > Anyone have any thoughts on what I can do to fix this? >AR is not smart enough to parse your sql fragments and qualify table names. You''d probably have to basically parse the sql exactly as the database does to do that. What you can do is have an interpolated condition. Off the top of my head, :conditions => ''...#{aliased_table_name}.start_time...'', ... The single quotes are important. Fred> Thanks, > Luke > -- > Posted via http://www.ruby-forum.com/. > > >--~--~---------~--~----~------------~-------~--~----~ 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 rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
Frederick Cheung wrote:> On 4 Sep 2008, at 07:01, Luke Ivers wrote: > >> 0''], :order => ''start_time desc'' >> >> >> >> Anyone have any thoughts on what I can do to fix this? >> > AR is not smart enough to parse your sql fragments and qualify table > names. You''d probably have to basically parse the sql exactly as the > database does to do that. > > What you can do is have an interpolated condition. Off the top of my > head, > > :conditions => ''...#{aliased_table_name}.start_time...'', ... > > The single quotes are important. > > FredActually: I JUST found this out right before I read your reply: If you, in your conditions, specify the table name, so in my case something like: has_many :next_tasks, :class_name => ''Task'', :foreign_key => ''candidate_id'', :conditions => [''tasks.start_time > now() and not tasks.deleted = 0''], :order => ''start_time'' When it does the join, it WILL automatically replace the tasks. part with the correct entry from the SQL query that it generates. Thanks for the help, though, it''s good to know that the alternative option exists as well. :) -Luke -- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ 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 rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---