Added Base.validate_uniqueness thatv alidates whether the value of the specified attributes are unique across the system. Useful for making sure that only one user can be named "davidhh".

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@108 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

3 files changed, 30 insertions, 6 deletions

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index cc76204dc0..2346aa19e9 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -665,7 +665,7 @@ module ActiveRecord #:nodoc:
           end
 
           until values.empty?
-            statement.sub!(/\?/, connection.quote(values.shift))
+            statement.sub!(/\?/, encode_quoted_value(values.shift))
           end
           
           statement.gsub('?') { |all, match| connection.quote(values.shift) }
@@ -674,7 +674,7 @@ module ActiveRecord #:nodoc:
         def replace_named_bind_variables(statement, values_hash)
           orig_statement = statement.clone
           values_hash.keys.each do |k|
-            if statement.sub!(/:#{k.id2name}/, connection.quote(values_hash.delete(k))).nil?
+            if statement.sub!(/:#{k.id2name}/, encode_quoted_value(values_hash.delete(k))).nil?
               raise PreparedStatementInvalid, ":#{k} is not a variable in [#{orig_statement}]"
             end
           end
@@ -685,6 +685,12 @@ module ActiveRecord #:nodoc:
 
           return statement
         end
+        
+        def encode_quoted_value(value)
+          quoted_value = connection.quote(value)
+          quoted_value = "'#{quoted_value[1..-2].gsub(/\'/, "\\\\'")}'" if quoted_value.include?("\\\'")          
+          quoted_value
+        end
     end
 
     public
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
index 1a26057528..87bad183ab 100755
--- a/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_adapter.rb
@@ -324,7 +324,7 @@ module ActiveRecord
 
       def quote(value, column = nil)
         case value
-          when String                then "'#{quote_string(value)}'" # ' (for ruby-mode)
+          when String                then %('#{quote_string(value)}') # ' (for ruby-mode)
           when NilClass              then "NULL"
           when TrueClass             then (column && column.type == :boolean ? "'t'" : "1")
           when FalseClass            then (column && column.type == :boolean ? "'f'" : "0")
diff --git a/activerecord/lib/active_record/validations.rb b/activerecord/lib/active_record/validations.rb
index 17810318b7..b2e7b1e99b 100755
--- a/activerecord/lib/active_record/validations.rb
+++ b/activerecord/lib/active_record/validations.rb
@@ -74,7 +74,6 @@ module ActiveRecord
       # situations.
       def validate_confirmation(*attr_names)
         error_message = attr_names.last.is_a?(String) ? attr_names.pop : "doesn't match confirmation"
-
         validation_method = block_given? ? yield : "validate"
 
         for attr_name in attr_names
@@ -111,7 +110,6 @@ module ActiveRecord
       # NOTE: The agreement is considered valid if it's set to the string "1". This makes it easy to relate it to an HTML checkbox.
       def validate_acceptance(*attr_names)
         error_message = attr_names.last.is_a?(String) ? attr_names.pop : "must be accepted"
-        
         validation_method = block_given? ? yield : "validate"
         
         for attr_name in attr_names
@@ -132,7 +130,6 @@ module ActiveRecord
 
       def validate_presence(*attr_names)
         error_message = attr_names.last.is_a?(String) ? attr_names.pop : "can't be empty"
-
         validation_method = block_given? ? yield : "validate"
 
         for attr_name in attr_names
@@ -149,6 +146,27 @@ module ActiveRecord
       def validate_presence_on_update(*attr_names)
         validate_presence(*attr_names) { "validate_on_update" }
       end
+
+      # Validates whether the value of the specified attributes are unique across the system. Useful for making sure that only one user
+      # can be named "davidhh".
+      #
+      #   Model:
+      #     class Person < ActiveRecord::Base
+      #       validate_uniqueness :user_name
+      #     end
+      #
+      #   View:
+      #     <%= text_field "person", "user_name" %>
+      #
+      # When the record is created, a check is performed to make sure that no record exist in the database with the given value for the specified
+      # attribute (that maps to a column). When the record is updated, the same check is made but disregarding the record itself.
+      def validate_uniqueness(*attr_names)
+        error_message = attr_names.last.is_a?(String) ? attr_names.pop : "has already been taken"
+
+        for attr_name in attr_names
+          class_eval(%(validate %{errors.add("#{attr_name}", "#{error_message}") if self.class.find_first(new_record? ? ["#{attr_name} = ?", #{attr_name}] : ["#{attr_name} = ? AND id <> ?", #{attr_name}, id])}))
+        end
+      end
     end
 
     # The validation process on save can be skipped by passing false. The regular Base#save method is