Clarified intentions of validates_associated #870

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@1602 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/lib/active_record/validations.rb

@@ -572,7 +572,10 @@ def validates_exclusion_of(*attr_names)
       #     validates_associated :book
       #   end
       #
-      # this would specify a circular dependency and cause infinite recursion. The Rails team recommends against this practice.
+      # ...this would specify a circular dependency and cause infinite recursion.
+      #
+      # NOTE: This validation will not fail if the association hasn't been assigned. If you want to ensure that the association
+      # is both present and guaranteed to be valid, you also need to use validates_presence_of.
       #
       # Configuration options:
       # * <tt>on</tt> Specifies when this validation is active (default is :save, other options :create, :update)

activerecord/test/validations_test.rb

@@ -784,4 +784,14 @@ def test_conditional_validation_using_block_false
     assert t.valid?
     assert !t.errors.on(:title)
   end
-end
+
+  def test_validates_associated_missing
+    Reply.validates_presence_of(:topic)
+    r = Reply.create("title" => "A reply", "content" => "with content!")
+    assert !r.valid?
+    assert r.errors.on(:topic)
+    
+    r.topic = Topic.find :first
+    assert r.valid?
+  end
+end
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