diff options
| -rw-r--r-- | activerecord/CHANGELOG | 4 | ||||
| -rwxr-xr-x | activerecord/lib/active_record/associations.rb | 10 |
2 files changed, 12 insertions, 2 deletions
diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG index ad7d0a668d..37d0ca53e4 100644 --- a/activerecord/CHANGELOG +++ b/activerecord/CHANGELOG @@ -1,6 +1,8 @@ *SVN* -* Docs: warn that associations names shouldn't be reserved words. #4378 [murphy@cYcnus.de, Josh Susser] +* Document deep eager includes. #6267 [Josh Susser, Dan Manges] + +* Document warning that associations names shouldn't be reserved words. #4378 [murphy@cYcnus.de, Josh Susser] * Sanitize Base#inspect. #8392 [Nik Wakelin] diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb index 85696505ab..b13c34d59c 100755 --- a/activerecord/lib/active_record/associations.rb +++ b/activerecord/lib/active_record/associations.rb @@ -422,7 +422,15 @@ module ActiveRecord # for post in Post.find(:all, :include => [ :author, :comments ]) # # That'll add another join along the lines of: LEFT OUTER JOIN comments ON comments.post_id = posts.id. And we'll be down to 1 query. - # But that shouldn't fool you to think that you can pull out huge amounts of data with no performance penalty just because you've reduced + # + # To include a deep hierarchy of associations, using a hash: + # + # for post in Post.find(:all, :include => [ :author, { :comments => { :author => :gravatar } } ]) + # + # That'll grab not only all the comments but all their authors and gravatar pictures. You can mix and match + # symbols, arrays and hashes in any combination to describe the associations you want to load. + # + # All of this power shouldn't fool you into thinking that you can pull out huge amounts of data with no performance penalty just because you've reduced # the number of queries. The database still needs to send all the data to Active Record and it still needs to be processed. So it's no # catch-all for performance problems, but it's a great way to cut down on the number of queries in a situation as the one described above. # |