mirror of
https://github.com/github/rails.git
synced 2026-02-09 05:35:14 -05:00
STI associations are now aliased to the table name for backwards compatibility. Added docs for table aliasing [Rick Olson]
git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@4015 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
This commit is contained in:
Rick Olson
@@ -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
|
||||
|
||||
Reference in New Issue
Block a user