Added support for validates_uniqueness_of in PostgreSQL array columns. Fixes: #8075.

activerecord/CHANGELOG.md

@@ -1,5 +1,10 @@
 ## Rails 4.0.0 (unreleased) ##
 
+*   Added support for `validates_uniqueness_of` in PostgreSQL array columns.
+    Fixes #8075.
+
+    *Pedro Padron*
+
 *   Allow int4range and int8range columns to be created in PostgreSQL and properly convert to/from database.
 
     *Alexey Vasiliev aka leopard*

activerecord/lib/active_record/validations/uniqueness.rb

@@ -71,7 +71,12 @@ module ActiveRecord
         end
 
         column = klass.columns_hash[attribute.to_s]
-        value = column.limit ? value.to_s[0, column.limit] : value.to_s if !value.nil? && column.text?
+
+        if !value.nil? && column.text? && column.limit
+          value = value.to_s[0, column.limit]
+        else
+          value = klass.connection.type_cast(value, column)
+        end
 
         if !options[:case_sensitive] && value && column.text?
           # will use SQL LOWER function before comparison, unless it detects a case insensitive collation

activerecord/test/cases/validations/uniqueness_validation_test.rb

@@ -30,6 +30,11 @@ class ReplyWithTitleObject < Reply
   def title; ReplyTitle.new; end
 end
 
+class Employee < ActiveRecord::Base
+  self.table_name = 'postgresql_arrays'
+  validates_uniqueness_of :nicknames
+end
+
 class UniquenessValidationTest < ActiveRecord::TestCase
   fixtures :topics, 'warehouse-things', :developers
 
@@ -341,16 +346,28 @@ class UniquenessValidationTest < ActiveRecord::TestCase
     assert w6.errors[:city].any?, "Should have errors for city"
     assert_equal ["has already been taken"], w6.errors[:city], "Should have uniqueness message for city"
   end
-  
+
   def test_validate_uniqueness_with_conditions
     Topic.validates_uniqueness_of(:title, :conditions => Topic.where('approved = ?', true))
     Topic.create("title" => "I'm a topic", "approved" => true)
     Topic.create("title" => "I'm an unapproved topic", "approved" => false)
-    
+
     t3 = Topic.new("title" => "I'm a topic", "approved" => true)
     assert !t3.valid?, "t3 shouldn't be valid"
-    
+
     t4 = Topic.new("title" => "I'm an unapproved topic", "approved" => false)
     assert t4.valid?, "t4 should be valid"
   end
+
+  def test_validate_uniqueness_with_array_column
+    return skip "Uniqueness on arrays has only been tested in PostgreSQL so far." if !current_adapter? :PostgreSQLAdapter
+
+    e1 = Employee.create("nicknames" => ["john", "johnny"], "commission_by_quarter" => [1000, 1200])
+    assert e1.persisted?, "Saving e1"
+
+    e2 = Employee.create("nicknames" => ["john", "johnny"], "commission_by_quarter" => [2200])
+    assert !e2.persisted?, "e2 shouldn't be valid"
+    assert e2.errors[:nicknames].any?, "Should have errors for nicknames"
+    assert_equal ["has already been taken"], e2.errors[:nicknames], "Should have uniqueness message for nicknames"
+  end
 end