diff options
Diffstat (limited to 'activerecord')
| -rwxr-xr-x | activerecord/lib/active_record/associations.rb | 63 |
1 files changed, 54 insertions, 9 deletions
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb index 6f149d16e0..24ba392190 100755 --- a/activerecord/lib/active_record/associations.rb +++ b/activerecord/lib/active_record/associations.rb @@ -261,9 +261,57 @@ module ActiveRecord # in both conditions and orders. So :order => "posts.id DESC" will work while :order => "id DESC" will not. This may require that # you alter the :order and :conditions on the association definitions themselves. # - # It's currently not possible to use eager loading on multiple associations from the same table. Eager loading will also not pull + # It's currently not possible to use eager loading on multiple associations from the same table. Eager loading will not pull # additional attributes on join tables, so "rich associations" with has_and_belongs_to_many is not a good fit for eager loading. # + # == Table Aliasing + # + # ActiveRecord uses table aliasing in the case that a table is referenced multiple times in a join. If a table is referenced only once, + # the standard table name is used. The second time, the table is aliased as #{reflection_name}_#{parent_table_name}. Indexes are appended + # for any more successive uses of the table name. + # + # Post.find :all, :include => :comments + # # => SELECT ... FROM posts LEFT OUTER JOIN comments ON ... + # Post.find :all, :include => :special_comments # STI + # # => SELECT ... FROM posts LEFT OUTER JOIN comments ON ... AND comments.type = 'SpecialComment' + # Post.find :all, :include => [:comments, :special_comments] # special_comments is the reflection name, posts is the parent table name + # # => SELECT ... FROM posts LEFT OUTER JOIN comments ON ... LEFT OUTER JOIN comments special_comments_posts + # + # Acts as tree example: + # + # TreeMixin.find :all, :include => :children + # # => SELECT ... FROM mixins LEFT OUTER JOIN mixins childrens_mixins ... + # TreeMixin.find :all, :include => {:children => :parent} # using cascading eager includes + # # => SELECT ... FROM mixins LEFT OUTER JOIN mixins childrens_mixins ... + # LEFT OUTER JOIN parents_mixins ... + # TreeMixin.find :all, :include => {:children => {:parent => :children}} + # # => SELECT ... FROM mixins LEFT OUTER JOIN mixins childrens_mixins ... + # LEFT OUTER JOIN parents_mixins ... + # LEFT OUTER JOIN mixins childrens_mixins_2 + # + # Has and Belongs to Many join tables use the same idea, but add a _join suffix: + # + # Post.find :all, :include => :categories + # # => SELECT ... FROM posts LEFT OUTER JOIN categories_posts ... LEFT OUTER JOIN categories ... + # Post.find :all, :include => {:categories => :posts} + # # => SELECT ... FROM posts LEFT OUTER JOIN categories_posts ... LEFT OUTER JOIN categories ... + # LEFT OUTER JOIN categories_posts posts_categories_join LEFT OUTER JOIN posts posts_categories + # Post.find :all, :include => {:categories => {:posts => :categories}} + # # => SELECT ... FROM posts LEFT OUTER JOIN categories_posts ... LEFT OUTER JOIN categories ... + # LEFT OUTER JOIN categories_posts posts_categories_join LEFT OUTER JOIN posts posts_categories + # LEFT OUTER JOIN categories_posts categories_posts_join LEFT OUTER JOIN categories categories_posts + # + # If you wish to specify your own custom joins using a :joins option, those table names will take precedence over the eager associations.. + # + # Post.find :all, :include => :comments, :joins => "inner join comments ..." + # # => SELECT ... FROM posts LEFT OUTER JOIN comments_posts ON ... INNER JOIN comments ... + # Post.find :all, :include => [:comments, :special_comments], :joins => "inner join comments ..." + # # => SELECT ... FROM posts LEFT OUTER JOIN comments comments_posts ON ... + # LEFT OUTER JOIN comments special_comments_posts ... + # INNER JOIN comments ... + # + # Table aliases are automatically truncated according to the maximum length of table identifiers according to the specific database. + # # == Modules # # By default, associations will look for objects within the current module scope. Consider: @@ -1257,10 +1305,10 @@ module ActiveRecord @parent = parent @reflection = reflection @aliased_prefix = "t#{ join_dependency.joins.size }" - @aliased_table_name = sti? ? pluralize(reflection.name) : table_name # start with the table name - @parent_table_name = sti? ? pluralize(parent.active_record.name.underscore) : parent.active_record.table_name + @aliased_table_name = table_name # start with the table name + @parent_table_name = parent.active_record.table_name - if !parent.table_joins.blank? && parent.table_joins =~ %r{#{aliased_table_name}} + if !parent.table_joins.blank? && parent.table_joins.to_s.downcase =~ %r{join(\s+\w+)?\s+#{aliased_table_name.downcase}\son} join_dependency.table_aliases[aliased_table_name] += 1 end @@ -1270,6 +1318,7 @@ module ActiveRecord table_index = join_dependency.table_aliases[aliased_table_name] @aliased_table_name = @aliased_table_name[0..active_record.connection.table_alias_length-3] + "_#{table_index+1}" if table_index > 0 end + if reflection.macro == :has_and_belongs_to_many || (reflection.macro == :has_many && reflection.options[:through]) @aliased_join_table_name = reflection.macro == :has_and_belongs_to_many ? reflection.options[:join_table] : parent.active_record.reflect_on_association(reflection.options[:through]).klass.table_name unless join_dependency.table_aliases[aliased_join_table_name].zero? @@ -1362,16 +1411,12 @@ module ActiveRecord join << %(AND %s.%s = %s ) % [ aliased_table_name, reflection.active_record.connection.quote_column_name(reflection.active_record.inheritance_column), - klass.quote(klass.name)] if sti? + klass.quote(klass.name)] unless klass.descends_from_active_record? join << "AND #{interpolate_sql(sanitize_sql(reflection.options[:conditions]))} " if reflection.options[:conditions] join end protected - def sti? - !klass.descends_from_active_record? - end - def pluralize(table_name) ActiveRecord::Base.pluralize_table_names ? table_name.to_s.pluralize : table_name end |