Subqueries in select clause (fixes activerecord-hackery#20)

lib/squeel/adapters/active_record.rb

@@ -1,3 +1,5 @@
+ActiveRecord::Relation.send :include, Squeel::Nodes::Aliasing
+
 case ActiveRecord::VERSION::MAJOR
 when 3
   case ActiveRecord::VERSION::MINOR

lib/squeel/adapters/active_record/3.0/compat.rb

@@ -1,5 +1,11 @@
 module Arel
 
+  class SelectManager
+    def as other
+      Nodes::TableAlias.new Nodes::SqlLiteral.new(other), Nodes::Grouping.new(@ast)
+    end
+  end
+
   class Table
     alias :table_name :name
 
@@ -130,6 +136,11 @@ def visit_Arel_Nodes_Values o
           end
         }.join ', '})"
       end
+
+      def quote_table_name name
+        return name if Arel::Nodes::SqlLiteral === name
+        @quoted_tables[name] ||= @connection.quote_table_name(name)
+      end
     end
   end
 

lib/squeel/adapters/active_record/relation.rb

@@ -101,7 +101,7 @@ def build_arel
         end
 
         # reverse_sql_order doesn't understand ARel ordering nodes, so we
-        # need to convert them to their corresponding SQL
+        # need to convert them to their corresponding SQL (for now)
         def sqlify_order(order)
           order.map do |o|
             o.respond_to?(:to_sql) ? o.to_sql : o

lib/squeel/nodes/as.rb

@@ -4,6 +4,9 @@ module Squeel
   module Nodes
     # A node representing an SQL alias, which will result in same when visited.
     class As < Binary
+      alias :expr :left
+      alias :alias :right
+
       # @param left The node to be aliased
       # @param right The alias name
       def initialize(left, right)

lib/squeel/version.rb

@@ -1,3 +1,3 @@
 module Squeel
-  VERSION = "0.8.0"
+  VERSION = "0.8.1"
 end

lib/squeel/visitors/attribute_visitor.rb

@@ -145,6 +145,15 @@ def visit_Squeel_Nodes_As(o, parent)
         accept(o.left, parent).as(o.right)
       end
 
+      # Visit an ActiveRecord Relation, returning an Arel::SelectManager
+      # @param [ActiveRecord::Relation] o The Relation to visit
+      # @param parent The parent object in the context
+      # @return [Arel::SelectManager] The ARel select manager that represents
+      #   the relation's query
+      def visit_ActiveRecord_Relation(o, parent)
+        o.arel
+      end
+
       # @return [Boolean] Whether the given value implies a context change
       # @param v The value to consider
       def implies_context_change?(v)

spec/squeel/adapters/active_record/relation_spec.rb

@@ -366,6 +366,13 @@ module ActiveRecord
             relation.first.flanderized_name.should eq 'Aric Smith-diddly'
           end
 
+          it 'allows a subquery in the select values' do
+            subquery = Article.where(:person_id => 1).select(:id).order{id.desc}.limit(1)
+            relation = Person.where(:id => 1).select{[id, name, subquery.as('last_article_id')]}
+            aric = relation.first
+            aric.last_article_id.should eq Article.where(:person_id => 1).last.id
+          end
+
         end
 
         describe '#group' do
@@ -583,6 +590,18 @@ module ActiveRecord
 
         end
 
+        describe '#as' do
+
+          it 'aliases the relation in an As node' do
+            relation = Person.where{name == 'ernie'}
+            node = relation.as('ernie')
+            node.should be_a Squeel::Nodes::As
+            node.expr.should eq relation
+            node.alias.should eq 'ernie'
+          end
+
+        end
+
         describe '#merge' do
 
           it 'merges relations with the same base' do

spec/squeel/visitors/attribute_visitor_spec.rb

@@ -67,6 +67,12 @@ module Visitors
         ordering.direction.should eq :asc
       end
 
+      it 'allows a subquery as a selection' do
+        relation = Person.where(:name => 'Aric Smith').select(:id)
+        node = @v.accept(relation.as('aric'))
+        node.to_sql.should be_like "(SELECT \"people\".\"id\" FROM \"people\"  WHERE \"people\".\"name\" = 'Aric Smith') aric"
+      end
+
       it 'creates an ARel NamedFunction node for a Function node' do
         function = @v.accept(:find_in_set.func())
         function.should be_a Arel::Nodes::NamedFunction