don't cache invalid subsets when preloading hmt associations.

closes #8423.

1 files changed, 22 insertions, 0 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 4fa37cc5c2..4489ca1aff 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,5 +1,27 @@
 ## Rails 4.0.0 (unreleased) ##
 
+*   Preloading `has_many :through` associations with conditions won't
+    cache the `:through` association. This will prevent invalid
+    subsets to be cached.
+    Fixes #8423.
+
+    Example:
+
+        class User
+          has_many :posts
+          has_many :recent_comments, -> { where('created_at > ?', 1.week.ago) }, :through => :posts
+        end
+
+        a_user = User.includes(:recent_comments).first
+
+        # this is preloaded
+        a_user.recent_comments
+
+        # fetching the recent_comments through the posts association won't preload it.
+        a_user.posts
+
+    *Yves Senn*
+
 *   Don't run after_commit callback when creating through an association
     if saving the record fails.