Allow validate_uniqueness_of to be scoped by more than just one column. Closes #1559.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3206 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

 *SVN*
 
+* Allow validate_uniqueness_of to be scoped by more than just one column.  #1559. [jeremy@jthopple.com, Marcel Molina Jr.]
+
 * Firebird: active? and reconnect! methods for handling stale connections.  #428 [Ken Kunz <kennethkunz@gmail.com>]
 
 * Firebird: updated for FireRuby 0.4.0.  #3009 [Ken Kunz <kennethkunz@gmail.com>]

activerecord/lib/active_record/validations.rb

@@ -471,7 +471,14 @@ def validates_length_of(*attrs)
       # can be named "davidhh".
       #
       #   class Person < ActiveRecord::Base
-      #     validates_uniqueness_of :user_name, :scope => "account_id"
+      #     validates_uniqueness_of :user_name, :scope => :account_id
+      #   end
+      #
+      # It can also validate whether the value of the specified attributes are unique based on multiple scope parameters.  For example,
+      # making sure that a teacher can only be on the schedule once per semester for a particular class. 
+      #
+      #   class TeacherSchedule < ActiveRecord::Base
+      #     validates_uniqueness_of :teacher_id, :scope => [:semester_id, :class_id] 
       #   end
       #
       # When the record is created, a check is performed to make sure that no record exists in the database with the given value for the specified
@@ -479,10 +486,11 @@ def validates_length_of(*attrs)
       #
       # Configuration options:
       # * <tt>message</tt> - Specifies a custom error message (default is: "has already been taken")
-      # * <tt>scope</tt> - Ensures that the uniqueness is restricted to a condition of "scope = record.scope"
+      # * <tt>scope</tt> - One or more columns by which to limit the scope of the uniquness constraint.
       # * <tt>if</tt> - Specifies a method, proc or string to call to determine if the validation should
       # occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }).  The
       # method, proc or string should return or evaluate to a true or false value.
+       
       def validates_uniqueness_of(*attr_names)
         configuration = { :message => ActiveRecord::Errors.default_error_messages[:taken] }
         configuration.update(attr_names.pop) if attr_names.last.is_a?(Hash)
@@ -491,9 +499,11 @@ def validates_uniqueness_of(*attr_names)
           condition_sql = "#{attr_name} #{attribute_condition(value)}"
           condition_params = [value]
           if scope = configuration[:scope]
-            scope_value = record.send(scope)
-            condition_sql << " AND #{scope} #{attribute_condition(scope_value)}"
-            condition_params << scope_value
+            Array(scope).map do |scope_item|
+              scope_value = record.send(scope_item)
+              condition_sql << " AND #{scope_item} #{attribute_condition(scope_value)}"
+              condition_params << scope_value
+            end
           end
           unless record.new_record?
             condition_sql << " AND #{record.class.primary_key} <> ?"

activerecord/test/validations_test.rb

@@ -280,6 +280,30 @@ def test_validate_uniqueness_with_scope
     assert r3.valid?, "Saving r3"
   end
 
+  def test_validate_uniqueness_with_scope_array
+    Reply.validates_uniqueness_of(:author_name, :scope => [:author_email_address, :parent_id])
+
+    t = Topic.create("title" => "The earth is actually flat!")
+ 
+    r1 = t.replies.create "author_name" => "jeremy", "author_email_address" => "jeremy@rubyonrails.com", "title" => "You're crazy!", "content" => "Crazy reply"
+    assert r1.valid?, "Saving r1"
+    
+    r2 = t.replies.create "author_name" => "jeremy", "author_email_address" => "jeremy@rubyonrails.com", "title" => "You're crazy!", "content" => "Crazy reply again..."
+    assert !r2.valid?, "Saving r2. Double reply by same author." 
+    
+    r2.author_email_address = "jeremy_alt_email@rubyonrails.com"
+    assert r2.save, "Saving r2 the second time." 
+    
+    r3 = t.replies.create "author_name" => "jeremy", "author_email_address" => "jeremy_alt_email@rubyonrails.com", "title" => "You're wrong", "content" => "It's cubic"
+    assert !r3.valid?, "Saving r3"
+    
+    r3.author_name = "jj"
+    assert r3.save, "Saving r3 the second time."
+    
+    r3.author_name = "jeremy"
+    assert !r3.save, "Saving r3 the third time."
+  end
+
   def test_validate_format
     Topic.validates_format_of(:title, :content, :with => /^Validation\smacros \w+!$/, :message => "is bad data")