From 7780a13fe8f66f59bfbb0e18f91f067d699a2ded Mon Sep 17 00:00:00 2001
From: Alexey Verkhovsky <averkhov@thoughtworks.com>
Date: Mon, 17 Jan 2005 21:22:41 +0000
Subject: [PATCH] Created a special error class for handling graecful rollbacks
 (not sure if Madeleine can take it yet)

---
 config/environment.rb       |  1 +
 libraries/instiki_errors.rb | 15 +++++++++++++++
 2 files changed, 16 insertions(+)
 create mode 100644 libraries/instiki_errors.rb

diff --git a/config/environment.rb b/config/environment.rb
index f38efb72..6e038c7a 100644
--- a/config/environment.rb
+++ b/config/environment.rb
@@ -42,6 +42,7 @@ end
 
 require 'action_controller'
 require 'active_record_stub'
+require 'instiki_errors'
 
 unless defined? RAILS_DEFAULT_LOGGER
   RAILS_DEFAULT_LOGGER = Logger.new(STDERR)
diff --git a/libraries/instiki_errors.rb b/libraries/instiki_errors.rb
new file mode 100644
index 00000000..52efc571
--- /dev/null
+++ b/libraries/instiki_errors.rb
@@ -0,0 +1,15 @@
+# Model methods that want to rollback transactions gracefully 
+# (i.e, returning the user back to the form from which the request was posted)
+# should raise Instiki::ValidationError.
+# 
+# E.g. if a model object does
+#   raise "Foo: '#{foo}' is not equal to Bar: '#{bar}'" if (foo != bar) 
+# 
+# then the operation is not committed; Rails returns the user to the page 
+# where s/he was entering foo and bar, and the error message will be displayed 
+# on the page
+
+module Instiki
+  class ValidationError < StandardError
+  end
+end
\ No newline at end of file