added fk validation dodge example

Nick Gauthier · Nick Gauthier · commit 2ef76cb6e4ad · 2010-09-05T11:02:55.000-05:00
diff --git a/chapter-2/01-fks.md b/chapter-2/01-fks.md
@@ -0,0 +1,9 @@
+Comment.belongs_to Post
+
+p = Post.new
+c = Comment.new(:post => p)
+p.destroy
+ => true
+c.reload; c.valid?
+ => false
+# but it's in the DB!
