aliasing of relations

6 files changed, 35 insertions, 9 deletions

diff --git a/lib/active_relation/primitives/attribute.rb b/lib/active_relation/primitives/attribute.rb
index 65ae12cf36..b13f9befe1 100644
--- a/lib/active_relation/primitives/attribute.rb
+++ b/lib/active_relation/primitives/attribute.rb
@@ -9,8 +9,8 @@ module ActiveRelation
         @relation, @name, @alias = relation, name, aliaz
       end
   
-      def alias(aliaz = nil)
-        aliaz ? Attribute.new(relation, name, aliaz) : @alias
+      def as(aliaz = nil)
+        Attribute.new(relation, name, aliaz)
       end
   
       def qualified_name
@@ -18,7 +18,7 @@ module ActiveRelation
       end
   
       def qualify
-        self.alias(qualified_name)
+        self.as(qualified_name)
       end
   
       def ==(other)
diff --git a/lib/active_relation/relations.rb b/lib/active_relation/relations.rb
index a25e82f607..1eb58d3b42 100644
--- a/lib/active_relation/relations.rb
+++ b/lib/active_relation/relations.rb
@@ -8,4 +8,5 @@ require 'active_relation/relations/order'
 require 'active_relation/relations/range'
 require 'active_relation/relations/rename'
 require 'active_relation/relations/deletion'
-require 'active_relation/relations/insertion'
\ No newline at end of file
+require 'active_relation/relations/insertion'
+require 'active_relation/relations/alias'
\ No newline at end of file
diff --git a/lib/active_relation/relations/alias.rb b/lib/active_relation/relations/alias.rb
new file mode 100644
index 0000000000..97950ea5b3
--- /dev/null
+++ b/lib/active_relation/relations/alias.rb
@@ -0,0 +1,19 @@
+module ActiveRelation
+  module Relations
+    class Alias < Compound
+      attr_reader :alias
+  
+      def initialize(relation, aliaz)
+        @relation, @alias = relation, aliaz
+      end
+  
+      def ==(other)
+        relation == other.relation and self.alias == other.alias
+      end
+      
+      def to_sql(options = {})
+        super + " AS #{@alias}"
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/active_relation/relations/base.rb b/lib/active_relation/relations/base.rb
index 960735f07f..b4654f8f4b 100644
--- a/lib/active_relation/relations/base.rb
+++ b/lib/active_relation/relations/base.rb
@@ -45,6 +45,10 @@ module ActiveRelation
         def project(*attributes)
           Projection.new(self, *attributes)
         end
+        
+        def as(aliaz)
+          Alias.new(self, aliaz)
+        end
   
         def order(*attributes)
           Order.new(self, *attributes)
@@ -75,8 +79,8 @@ module ActiveRelation
       end
   
       def to_sql(options = {})
-        [
-          "SELECT #{attributes.collect{ |a| a.to_sql(:use_alias => true) }.join(', ')}",
+        sql = [
+          "SELECT #{attributes.collect{ |a| a.to_sql(:use_alias => true, :use_parens => true) }.join(', ')}",
           "FROM #{quote_table_name(table)}",
           (joins.to_sql(:quote => false) unless joins.blank?),
           ("WHERE #{selects.collect{|s| s.to_sql(:quote => false)}.join("\n\tAND ")}" unless selects.blank?),
@@ -84,6 +88,7 @@ module ActiveRelation
           ("LIMIT #{limit.to_sql}" unless limit.blank?),
           ("OFFSET #{offset.to_sql}" unless offset.blank?)
         ].compact.join("\n")
+        options[:use_parens] ? "(#{sql})" : sql
       end
       alias_method :to_s, :to_sql
     
@@ -95,6 +100,7 @@ module ActiveRelation
       def joins;      nil end
       def limit;      nil end
       def offset;     nil end
+      def alias;      nil end
     end
   end
 end
\ No newline at end of file
diff --git a/lib/active_relation/relations/compound.rb b/lib/active_relation/relations/compound.rb
index 442224a011..26ee92b365 100644
--- a/lib/active_relation/relations/compound.rb
+++ b/lib/active_relation/relations/compound.rb
@@ -3,7 +3,7 @@ module ActiveRelation
     class Compound < Base
       attr_reader :relation
   
-      delegate :attributes, :attribute, :joins, :selects, :orders, :table, :inserts, :limit, :offset, :to => :relation
+      delegate :attributes, :attribute, :joins, :selects, :orders, :table, :inserts, :limit, :offset, :alias, :to => :relation
     end
   end
 end
\ No newline at end of file
diff --git a/lib/active_relation/relations/rename.rb b/lib/active_relation/relations/rename.rb
index c7b99c2127..cff042dbc6 100644
--- a/lib/active_relation/relations/rename.rb
+++ b/lib/active_relation/relations/rename.rb
@@ -23,7 +23,7 @@ module ActiveRelation
       protected
       def attribute(name)
         case
-        when name == self.alias then schmattribute.alias(self.alias)
+        when name == self.alias then schmattribute.as(self.alias)
         when relation[name] == schmattribute then nil
         else relation[name]
         end
@@ -31,7 +31,7 @@ module ActiveRelation
   
       private
       def substitute(a)
-        a == schmattribute ? a.alias(self.alias) : a
+        a == schmattribute ? a.as(self.alias) : a
       end
     end
   end