Rails - Aug 2005 - [RE-POST] Finding rows in table a with zero related rows in table b, part ii

Just a quick re-post of my query from the other day. If I could get any 
help with the nature of the error message that I''m receiving when I try
to call my "unassigned_list" method, that would be a big help.
Normally,
I wouldn''t re-post something after just 1 day, but I''m under
some
deadline pressure and this is really stopping my progress.

Thanks for any assistance...

-Brian

------------------------

OK. After a little more digging in MySQL''s manual on SubSelects,
I''ve
come up with this finder_sql entry in my model declaration for 
"unassigned_applicants":

class District < ActiveRecord::Base
	has_many 	:interviewers,
				:order => "lname, fname"
	has_many 	:applicants
	has_many 	:unassigned_applicants,
				:class_name => "Applicant",
				:finder_sql => "select a.* from applicants a left join 
applicants_interviewers ai " +
					"on a.id = ai.applicant_id where ai.applicant_id is null"
end

Running that SQL through the mysql command-line tool returns exactly the
data I''m looking for. However, in my district_controller.rb file,
I''ve
got this method:

	def unassigned_list
		@dist = District.find( params[:dist_id] )
		@applicants = @dist.unassigned_applicants.find( :all )
		@sub_title = "Unassigned Applicants (" + @applicants.size.to_s +
")"
		render :template => "district/app_list"
	end

When I go to the page that calls this method, it throws back this error:

NoMethodError in District#unassigned_list
undefined method `expects_array?'' for #<Array:0x2271d04>

I have no idea what this is trying to tell me. What is the
expects_array? method doing? Or trying to do?

-Brian

Can we see the stack trace?

Tyler

On 8/5/05, Brian V. Hughes
<brianvh-ilmOVS5JQ6Xj7r8U7pfrKh2eb7JE58TQ@public.gmane.org>
wrote:
> 
> Just a quick re-post of my query from the other day. If I could get any
> help with the nature of the error message that I''m receiving when
I try
> to call my "unassigned_list" method, that would be a big help.
Normally,
> I wouldn''t re-post something after just 1 day, but I''m
under some
> deadline pressure and this is really stopping my progress.
> 
> Thanks for any assistance...
> 
> -Brian
> 
> ------------------------
> 
> OK. After a little more digging in MySQL''s manual on SubSelects,
I''ve
> come up with this finder_sql entry in my model declaration for
> "unassigned_applicants":
> 
> class District < ActiveRecord::Base
>         has_many        :interviewers,
>                                 :order => "lname, fname"
>         has_many        :applicants
>         has_many        :unassigned_applicants,
>                                 :class_name => "Applicant",
>                                 :finder_sql => "select a.* from
applicants a left join
> applicants_interviewers ai " +
>                                         "on a.id = ai.applicant_id
where ai.applicant_id is null"
> end
> 
> Running that SQL through the mysql command-line tool returns exactly the
> data I''m looking for. However, in my district_controller.rb file,
I''ve
> got this method:
> 
>         def unassigned_list
>                 @dist = District.find( params[:dist_id] )
>                 @applicants = @dist.unassigned_applicants.find( :all )
>                 @sub_title = "Unassigned Applicants (" +
@applicants.size.to_s + ")"
>                 render :template => "district/app_list"
>         end
> 
> When I go to the page that calls this method, it throws back this error:
> 
> NoMethodError in District#unassigned_list
> undefined method `expects_array?'' for #<Array:0x2271d04>
> 
> I have no idea what this is trying to tell me. What is the
> expects_array? method doing? Or trying to do?
> 
> -Brian
> _______________________________________________
> Rails mailing list
> Rails-1W37MKcQCpIf0INCOvqR/iCwEArCW2h5@public.gmane.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>

Tyler Kiley wrote:
> Can we see the stack trace?
> 
> Tyler
Sure thing. I''ve looked at this before, but not knowing the internals
of
Rails, it almost never makes any sense to me. ;)

-Brian

/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.11.1/lib/active_record/associations/association_proxy.rb:24:in
`send''
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.11.1/lib/active_record/associations/association_proxy.rb:24:in
`method_missing''
/usr/local/lib/ruby/gems/1.8/gems/activerecord-1.11.1/lib/active_record/associations/has_many_association.rb:64:in
`find''
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.9.1/lib/action_controller/base.rb:756:in
`send''
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.9.1/lib/action_controller/base.rb:756:in
`perform_action_without_filters''
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.9.1/lib/action_controller/filters.rb:295:in
`perform_action_without_benchmark''
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.9.1/lib/action_controller/benchmarking.rb:41:in
`perform_action_without_rescue''
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.9.1/lib/action_controller/benchmarking.rb:41:in
`measure''
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.9.1/lib/action_controller/benchmarking.rb:41:in
`perform_action_without_rescue''
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.9.1/lib/action_controller/rescue.rb:80:in
`perform_action''
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.9.1/lib/action_controller/base.rb:356:in
`send''
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.9.1/lib/action_controller/base.rb:356:in
`process''
/usr/local/lib/ruby/gems/1.8/gems/rails-0.13.1/lib/dispatcher.rb:32:in 
`dispatch''
/usr/local/lib/ruby/gems/1.8/gems/rails-0.13.1/lib/webrick_server.rb:105:in 
`handle_dispatch''
/usr/local/lib/ruby/gems/1.8/gems/rails-0.13.1/lib/webrick_server.rb:71:in 
`service''
/usr/local/lib/ruby/1.8/webrick/httpserver.rb:104:in `service''
/usr/local/lib/ruby/1.8/webrick/httpserver.rb:65:in `run''
/usr/local/lib/ruby/1.8/webrick/server.rb:155:in `start_thread''
/usr/local/lib/ruby/1.8/webrick/server.rb:144:in `start''
/usr/local/lib/ruby/1.8/webrick/server.rb:144:in `start_thread''
/usr/local/lib/ruby/1.8/webrick/server.rb:94:in `start''
/usr/local/lib/ruby/1.8/webrick/server.rb:89:in `each''
/usr/local/lib/ruby/1.8/webrick/server.rb:89:in `start''
/usr/local/lib/ruby/1.8/webrick/server.rb:79:in `start''
/usr/local/lib/ruby/1.8/webrick/server.rb:79:in `start''
/usr/local/lib/ruby/gems/1.8/gems/rails-0.13.1/lib/webrick_server.rb:57:in 
`dispatch''

Wow... responding to my own question twice in a single day. Never done 
that before. :)

I''ve got my problem licked. Turns out I was handling the join stuff in 
the wrong location. Once I moved the join into the "find.(:all...)" 
statement, it worked like a charm:

def unassigned_list
	@dist = District.find( params[:dist_id] )
	@applicants = @dist.applicants.find( :all,
			:conditions 	=> "applicants_interviewers.applicant_id is null "
+
				"and applicants.decision != ''U3''",
			:order		=> @app_sort,
			:joins		=> "left join applicants_interviewers " +
				"on applicants.id = applicants_interviewers.applicant_id" )
	@sub_title = "Unassigned Applicants (" + @applicants.size.to_s +
")"
	render :template => "district/app_list"
end

Plus I was able to easily account for the extra condition this way. This 
was thanks to a response from Rick Olsen in the "Using find() in a 
habtm" thread.

I''m still interested in why I was getting the error and what the stack 
trace shows. So if that get''s posted to the list, that would be cool. 
But I think I''m all set now. Oh yeah... Rails is awesome! :)

-Brian



Brian V. Hughes wrote:
> OK. After a little more digging in MySQL''s manual on SubSelects,
I''ve
> come up with this finder_sql entry in my model declaration for 
> "unassigned_applicants":
> 
> class District < ActiveRecord::Base
>     has_many     :interviewers,
>                 :order => "lname, fname"
>     has_many     :applicants
>     has_many     :unassigned_applicants,
>                 :class_name => "Applicant",
>                 :finder_sql => "select a.* from applicants a left
join
> applicants_interviewers ai " +
>                     "on a.id = ai.applicant_id where ai.applicant_id
is
> null"
> end
> 
> Running that SQL through the mysql command-line tool returns exactly the
> data I''m looking for. However, in my district_controller.rb file,
I''ve
> got this method:
> 
>     def unassigned_list
>         @dist = District.find( params[:dist_id] )
>         @applicants = @dist.unassigned_applicants.find( :all )
>         @sub_title = "Unassigned Applicants (" +
@applicants.size.to_s +
> ")"
>         render :template => "district/app_list"
>     end