From 7c4681940763e430fc80dd3ecd71404450beb23b Mon Sep 17 00:00:00 2001
From: Lawrence Pit <lawrence.pit@gmail.com>
Date: Fri, 11 Sep 2009 16:18:34 +1000
Subject: [PATCH] Added errors_on and Errors.error methods

---
 activerecord/lib/active_record/validations.rb |   19 ++++++++++++++-
 activerecord/test/cases/validations_test.rb   |   31 +++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletions(-)

diff --git a/activerecord/lib/active_record/validations.rb b/activerecord/lib/active_record/validations.rb
index 1dc7c96..f2e024b 100644
--- a/activerecord/lib/active_record/validations.rb
+++ b/activerecord/lib/active_record/validations.rb
@@ -218,9 +218,18 @@ module ActiveRecord
       errors = @errors[attribute].map(&:to_s)
       errors.size == 1 ? errors.first : errors
     end
-
     alias :[] :on
 
+    # Returns +nil+, if no errors are associated with the specified +attribute+.
+    # Returns the error object, if one error is associated with the specified +attribute+.
+    # Returns an array of error objects, if more than one error is associated with the specified +attribute+.
+    def error(attribute)
+      attribute = attribute.to_s
+      return nil unless @errors.has_key?(attribute)
+      errors = @errors[attribute]
+      errors.size == 1 ? errors.first : errors
+    end
+
     # Returns errors assigned to the base object through +add_to_base+ according to the normal rules of <tt>on(attribute)</tt>.
     def on_base
       on(:base)
@@ -1122,6 +1131,14 @@ module ActiveRecord
       @errors ||= Errors.new(self)
     end
 
+    # Returns +nil+, if no errors are associated with the specified +attribute+.
+    # Returns the error object, if one error is associated with the specified +attribute+.
+    # Returns an array of error objects, if more than one error is associated with the specified +attribute+.
+    def errors_on(attribute)
+      errors.error(attribute)
+    end
+    alias_method :error_on, :errors_on
+
     protected
       # Overwrite this method for validation checks on all saves and use <tt>Errors.add(field, msg)</tt> for invalid attributes.
       def validate
diff --git a/activerecord/test/cases/validations_test.rb b/activerecord/test/cases/validations_test.rb
index 4c023c3..1fdad28 100644
--- a/activerecord/test/cases/validations_test.rb
+++ b/activerecord/test/cases/validations_test.rb
@@ -92,6 +92,37 @@ class ValidationsTest < ActiveRecord::TestCase
     assert_equal 2, r.errors.count
   end
 
+  def test_single_attr_double_error_msg
+    r = Reply.new
+    r.errors.add("title", "Foo")
+    r.errors.add("title", "Bar")
+    assert_equal 2, r.errors[:title].length
+    assert_equal 2, r.errors.on(:title).length
+    assert_equal "Foo", r.errors[:title][0]
+    assert_equal "Bar", r.errors[:title][1]
+  end
+
+  def test_single_attr_double_error_object
+    r = Reply.new
+    r.errors.add("title", "Foo")
+    r.errors.add("title", "Bar")
+    assert_equal 2, r.errors_on(:title).length
+    assert_equal "Foo", r.errors_on(:title)[0].message
+    assert_equal "Bar", r.errors_on(:title)[1].message
+  end
+
+  def test_single_attr_single_error_object
+    r = Reply.new
+    r.errors.add("title", "Foo")
+    assert_equal "Foo", r.errors_on(:title).message
+  end
+
+  def test_errors_on_aliased_with_error_on
+    r = Reply.new
+    r.errors.add("title", "Foo")
+    assert_equal "Foo", r.error_on(:title).message
+  end
+
   def test_error_on_create
     r = Reply.new
     r.title = "Wrong Create"
-- 
1.5.5.1