From 00a5fd3d18ac908af688c5944922cf69c56e850b Mon Sep 17 00:00:00 2001
From: Michael Schuerig <michael@schuerig.de>
Date: Sun, 5 Apr 2009 01:42:21 +0200
Subject: Translate foreign key violations to ActiveRecord::InvalidForeignKey
 exceptions.

Signed-off-by: Michael Koziarski <michael@koziarski.com>
---
 activerecord/lib/active_record/base.rb                            | 4 ++++
 .../lib/active_record/connection_adapters/mysql_adapter.rb        | 2 ++
 .../lib/active_record/connection_adapters/postgresql_adapter.rb   | 2 ++
 activerecord/test/cases/adapter_test.rb                           | 8 ++++++++
 4 files changed, 16 insertions(+)

(limited to 'activerecord')

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index defe1b56b6..027ab8af9e 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -71,6 +71,10 @@ module ActiveRecord #:nodoc:
   class RecordNotUnique < StatementInvalid
   end
 
+  # Raised when a record cannot be inserted or updated because it references a non-existent record.
+  class InvalidForeignKey < StatementInvalid
+  end
+
   # Raised when number of bind variables in statement given to <tt>:condition</tt> key (for example, when using +find+ method)
   # does not match number of expected variables.
   #
diff --git a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
index 59bf01e774..ae065e6bc1 100644
--- a/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/mysql_adapter.rb
@@ -569,6 +569,8 @@ module ActiveRecord
           case exception.errno
           when 1062
             RecordNotUnique.new(message)
+          when 1452
+            InvalidForeignKey.new(message)
           else
             super
           end
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index e990052e09..24482aa19a 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -945,6 +945,8 @@ module ActiveRecord
           case exception.message
           when /duplicate key value violates unique constraint/
             RecordNotUnique.new(message)
+          when /violates foreign key constraint/
+            InvalidForeignKey.new(message)
           else
             super
           end
diff --git a/activerecord/test/cases/adapter_test.rb b/activerecord/test/cases/adapter_test.rb
index 8688fbee49..80530194ff 100644
--- a/activerecord/test/cases/adapter_test.rb
+++ b/activerecord/test/cases/adapter_test.rb
@@ -137,4 +137,12 @@ class AdapterTest < ActiveRecord::TestCase
       @connection.execute "INSERT INTO subscribers(nick) VALUES('me')"
     end
   end
+
+  def test_foreign_key_violations_are_translated_to_specific_exception
+    unless @connection.adapter_name == 'SQLite'
+      assert_raises(ActiveRecord::InvalidForeignKey) do
+        @connection.execute "INSERT INTO fk_test_has_fk (fk_id) VALUES (0)"
+      end
+    end
+  end
 end
-- 
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