Has many through 3.1 beta

Debugger.rb

(rdb:1) pp o
#<Arel::Nodes::SelectCore:0x000001056b0638
 @groups=[],
 @having=nil,
 @projections=
  [#<struct Arel::Attributes::Attribute
    relation=
     #<Arel::Table:0x000001056aea68
      @aliases=[],
      @columns=nil,
      @engine=ActiveRecord::Base,
      @name="questions",
      @primary_key=nil,
      @table_alias=nil>,
    name="*">],
 @set_quantifier=nil,
 @source=
  #<Arel::Nodes::JoinSource:0x000001056b05c0
   @left=
    #<Arel::Table:0x00000105610c00
     @aliases=[],
     @columns=nil,
     @engine=ActiveRecord::Base,
     @name="questions",
     @primary_key=nil,
     @table_alias=nil>,
   @right=
    [#<Arel::Nodes::InnerJoin:0x000001056af2d8
      @left=
       #<Arel::Table:0x000001056af850
        @aliases=[],
        @columns=nil,
        @engine=ActiveRecord::Base,
        @name="questions_has_sections",
        @primary_key=nil,
        @table_alias=nil>,
      @right=
       #<Arel::Nodes::On:0x000001056af300
        @expr=
         #<Arel::Nodes::Equality:0x000001056af328
          @left=
           #<struct Arel::Attributes::Attribute
            relation=
             #<Arel::Table:0x000001056af850
              @aliases=[],
              @columns=nil,
              @engine=ActiveRecord::Base,
              @name="questions_has_sections",
              @primary_key=nil,
              @table_alias=nil>,
            name="question_id">,
          @right=
           #<struct Arel::Attributes::Attribute
            relation=
             #<Arel::Table:0x000001056af468
              @aliases=[],
              @columns=nil,
              @engine=ActiveRecord::Base,
              @name="questions",
              @primary_key=nil,
              @table_alias=nil>,
            name="id">>>>,
     #<Arel::Nodes::InnerJoin:0x00000105632fa8
      @left=
       #<Arel::Table:0x0000010562c400
        @aliases=[],
        @columns=nil,
        @engine=ActiveRecord::Base,
        @name="questions_has_sections",
        @primary_key=nil,
        @table_alias=nil>,
      @right=
       #<Arel::Nodes::On:0x00000105631b58
        @expr=
         #<Arel::Nodes::Equality:0x00000105631900
          @left=
           #<struct Arel::Attributes::Attribute
            relation=
             #<Arel::Table:0x000001055f8d58
              @aliases=[],
              @columns=nil,
              @engine=ActiveRecord::Base,
              @name="questions",
              @primary_key=nil,
              @table_alias=nil>,
            name="id">,
          @right=
           #<struct Arel::Attributes::Attribute
            relation=
             #<Arel::Table:0x0000010562c400
              @aliases=[],
              @columns=nil,
              @engine=ActiveRecord::Base,
              @name="questions_has_sections",
              @primary_key=nil,
              @table_alias=nil>,
            name="question_id">>>>]>,
 @top=nil,
 @wheres=
  [#<Arel::Nodes::And:0x000001056aeba8
    @children=
     [#<Arel::Nodes::Equality:0x0000010563d548
       @left=
        #<struct Arel::Attributes::Attribute
         relation=
          #<Arel::Table:0x0000010562c400
           @aliases=[],
           @columns=nil,
           @engine=ActiveRecord::Base,
           @name="questions_has_sections",
           @primary_key=nil,
           @table_alias=nil>,
         name="section_id">,
       @right=1>]>]>
(rdb:1) list
[125, 134] in /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/arel-2.1.0/lib/arel/visitors/to_sql.rb
   125          [
   126            "SELECT",
   127            (visit(o.top) if o.top),
   128            (visit(o.set_quantifier) if o.set_quantifier),
   129            ("#{o.projections.map { |x| visit x }.join ', '}" unless o.projections.empty?),
=> 130            (visit(o.source) if o.source),
   131            ("WHERE #{o.wheres.map { |x| visit x }.join ' AND ' }" unless o.wheres.empty?),
   132            ("GROUP BY #{o.groups.map { |x| visit x }.join ', ' }" unless o.groups.empty?),
   133            (visit(o.having) if o.having),
   134          ].compact.join ' '
(rdb:1) 

Final debugger WIN

(rdb:1) p target_scope.to_sql
"SELECT \"questions\".* FROM \"questions\" INNER JOIN \"questions_has_sections\" ON \"questions_has_sections\".\"question_id\" = \"questions\".\"id\""
(rdb:1) p @associaction_scope
nil
(rdb:1) list
[82, 91] in /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/bundler/gems/rails-2a98fd96aa2c/activerecord/lib/active_record/associations/association.rb
   82          @target = target
   83          loaded!
   84        end
   85  
   86        def scoped
=> 87          target_scope.merge(@association_scope)
   88        end
   89  
   90        # Construct the scope for this association.
   91        #
(rdb:1) p target_scope.merge(@association_scope).to_sql
"SELECT \"questions\".* FROM \"questions\" INNER JOIN \"questions_has_sections\" ON \"questions_has_sections\".\"question_id\" = \"questions\".\"id\" INNER JOIN \"questions_has_sections\" ON \"questions\".\"id\" = \"questions_has_sections\".\"question_id\" WHERE \"questions_has_sections\".\"section_id\" = 1"
(rdb:1) p target_scope.method[:merge]
ArgumentError Exception: wrong number of arguments(0 for 1)
(rdb:1) p target_scope.method(:merge)
#<Method: ActiveRecord::Relation(Squeel::Adapters::ActiveRecord::Relation)#merge>
(rdb:1) 

question.rb

class Question < ActiveRecord::Base
  has_many :questions_has_sections
  has_many :sections, :through => :questions_has_sections
end

questions_has_section.rb

# coding: utf-8
class QuestionsHasSection < ActiveRecord::Base
  belongs_to :question
  belongs_to :section
end

section.rb

class Section < ActiveRecord::Base
  has_many :questions_has_sections
  has_many :questions, :through => :questions_has_sections
end

Stacktrace

$ rails c
Loading development environment (Rails 3.1.0.beta1)
dok(dev)> Section.first.questions
  Section Load (0.3ms)  SELECT `sections`.* FROM `sections` LIMIT 1
  Question Load (0.2ms)  SELECT `questions`.* FROM `questions` INNER JOIN `questions_has_sections` ON `questions_has_sections`.`question_id` = `questions`.`id` INNER JOIN `questions_has_sections` ON `questions`.`id` = `questions_has_sections`.`question_id` WHERE `questions_has_sections`.`section_id` = 1
Mysql2::Error: Not unique table/alias: 'questions_has_sections': SELECT `questions`.* FROM `questions` INNER JOIN `questions_has_sections` ON `questions_has_sections`.`question_id` = `questions`.`id` INNER JOIN `questions_has_sections` ON `questions`.`id` = `questions_has_sections`.`question_id` WHERE `questions_has_sections`.`section_id` = 1
ActiveRecord::StatementInvalid: Mysql2::Error: Not unique table/alias: 'questions_has_sections': SELECT `questions`.* FROM `questions` INNER JOIN `questions_has_sections` ON `questions_has_sections`.`question_id` = `questions`.`id` INNER JOIN `questions_has_sections` ON `questions`.`id` = `questions_has_sections`.`question_id` WHERE `questions_has_sections`.`section_id` = 1
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/connection_adapters/mysql2_adapter.rb:657:in `query'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/connection_adapters/mysql2_adapter.rb:657:in `block in exec_query'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/connection_adapters/abstract_adapter.rb:222:in `block in log'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activesupport-3.1.0.beta1/lib/active_support/notifications/instrumenter.rb:21:in `instrument'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/connection_adapters/abstract_adapter.rb:217:in `log'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/connection_adapters/mysql2_adapter.rb:655:in `exec_query'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/connection_adapters/mysql2_adapter.rb:649:in `select'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/connection_adapters/abstract/database_statements.rb:12:in `select_all'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/connection_adapters/abstract/query_cache.rb:62:in `select_all'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/base.rb:469:in `find_by_sql'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/relation.rb:106:in `to_a'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/relation/finder_methods.rb:155:in `all'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/associations/has_many_through_association.rb:137:in `find_target'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/associations/collection_association.rb:327:in `load_target'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/associations/collection_proxy.rb:44:in `load_target'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/activerecord-3.1.0.beta1/lib/active_record/associations/collection_proxy.rb:73:in `method_missing'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/wirble-0.1.3/lib/wirble.rb:432:in `output_value'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/railties-3.1.0.beta1/lib/rails/commands/console.rb:44:in `start'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/railties-3.1.0.beta1/lib/rails/commands/console.rb:8:in `start'
	from /Users/fonsan/.rvm/gems/ruby-1.9.2-p180@dok/gems/railties-3.1.0.beta1/lib/rails/commands.rb:39:in `<top (required)>'
	from script/rails:6:in `require'
	from script/rails:6:in `<main>'dok(dev)