From e518a6ca32b506a76d68614312f803bcb55296da Mon Sep 17 00:00:00 2001
From: Phil Ross <phil.ross@gmail.com>
Date: Sun, 31 May 2009 15:13:10 +0100
Subject: [PATCH] Added a :case_sensitive => :db option to validates_uniqueness_of, which uses the database's case-sensitivity mode for comparisons.

---
 .../lib/active_record/validations/uniqueness.rb    |   11 +++++++++--
 .../validations/uniqueness_validation_test.rb      |   18 ++++++++++++++++++
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/activerecord/lib/active_record/validations/uniqueness.rb b/activerecord/lib/active_record/validations/uniqueness.rb
index edec4e9..7ddab26 100644
--- a/activerecord/lib/active_record/validations/uniqueness.rb
+++ b/activerecord/lib/active_record/validations/uniqueness.rb
@@ -21,7 +21,9 @@ module ActiveRecord
       # Configuration options:
       # * <tt>:message</tt> - Specifies a custom error message (default is: "has already been taken").
       # * <tt>:scope</tt> - One or more columns by which to limit the scope of the uniqueness constraint.
-      # * <tt>:case_sensitive</tt> - Looks for an exact match. Ignored by non-text columns (+true+ by default).
+      # * <tt>:case_sensitive</tt> - Set to true to look for an exact match or false to look for a
+      #   case insensitive match. Can also be set to :db to use the databases case-sensitivity mode for the column.
+      #   Ignored by non-text columns (+true+ by default).
       # * <tt>:allow_nil</tt> - If set to true, skips this validation if the attribute is +nil+ (default is +false+).
       # * <tt>:allow_blank</tt> - If set to true, skips this validation if the attribute is blank (default is +false+).
       # * <tt>:if</tt> - Specifies a method, proc or string to call to determine if the validation should
@@ -118,7 +120,12 @@ module ActiveRecord
           if value.nil?
             comparison_operator = "IS ?"
           elsif column.text?
-            comparison_operator = "#{connection.case_sensitive_equality_operator} ?"
+            if configuration[:case_sensitive] == :db
+              comparison_operator = "= ?"
+            else
+              comparison_operator = "#{connection.case_sensitive_equality_operator} ?"
+            end
+            
             value = column.limit ? value.to_s[0, column.limit] : value.to_s
           else
             comparison_operator = "= ?"
diff --git a/activerecord/test/cases/validations/uniqueness_validation_test.rb b/activerecord/test/cases/validations/uniqueness_validation_test.rb
index 961db51..7b8720e 100644
--- a/activerecord/test/cases/validations/uniqueness_validation_test.rb
+++ b/activerecord/test/cases/validations/uniqueness_validation_test.rb
@@ -170,6 +170,24 @@ class UniquenessValidationTest < ActiveRecord::TestCase
     end
   end
 
+  def test_validate_db_case_sensitive_uniqueness
+    Topic.validates_uniqueness_of(:title, :case_sensitive => :db, :allow_nil => true)
+
+    t = Topic.new(:title => "I'm unique!")
+    assert t.save, "Should save t"
+
+    db_case_insensitive = Topic.find_all_by_id_and_title(t.id, "I'm UNIQUE!").any?
+    
+    t2 = Topic.new(:title => db_case_insensitive ? "I'm UNIQUE!" : "I'm unique!")
+    assert !t2.valid?, "Shouldn't be valid"
+    assert !t2.save, "Shouldn't save t2 as unique"
+    assert t2.errors[:title].any?, "Should be errors for title"
+    assert_equal ["has already been taken"], t2.errors[:title]
+    
+    t3 = Topic.new(:title => db_case_insensitive ? "I'm truly UNIQUE!" : "I'm UNIQUE!")
+    assert t3.save, "Should save t3"
+  end
+  
   def test_validate_case_sensitive_uniqueness
     Topic.validates_uniqueness_of(:title, :case_sensitive => true, :allow_nil => true)
 
-- 
1.5.6.5