automatically aliasing tables

5 files changed, 39 insertions, 27 deletions

diff --git a/lib/arel/relations/grouping.rb b/lib/arel/relations/grouping.rb
index ccca600360..41af4ba0f6 100644
--- a/lib/arel/relations/grouping.rb
+++ b/lib/arel/relations/grouping.rb
@@ -15,5 +15,9 @@ module Arel
     def aggregation?
       true
     end
+    
+    def name
+      relation.name + '_aggregation'
+    end
   end
 end
\ No newline at end of file
diff --git a/lib/arel/relations/join.rb b/lib/arel/relations/join.rb
index e5ca49c284..ce236d79d0 100644
--- a/lib/arel/relations/join.rb
+++ b/lib/arel/relations/join.rb
@@ -24,9 +24,13 @@ module Arel
     end
     
     def prefix_for(attribute)
-      externalize([relation1[attribute], relation2[attribute]].select { |a| a =~ attribute }.min do |a1, a2|
+      name_for(relation_for(attribute))
+    end
+    
+    def relation_for(attribute)
+      [relation1[attribute], relation2[attribute]].select { |a| a =~ attribute }.min do |a1, a2|
         (attribute % a1).size <=> (attribute % a2).size
-      end.relation).prefix_for(attribute)
+      end.relation.relation_for(attribute)
     end
     
     # TESTME: Not sure which scenario needs this method, was driven by failing tests in ActiveRecord
@@ -34,10 +38,10 @@ module Arel
       (relation1[attribute] || relation2[attribute]).column
     end
     
-    def joins
+    def joins(formatter = Sql::TableReference.new(engine))
       this_join = [
         join_sql,
-        externalize(relation2).table_sql,
+        externalize(relation2).table_sql(formatter),
         ("ON" unless predicates.blank?),
         predicates.collect { |p| p.bind(self).to_sql }.join(' AND ')
       ].compact.join(" ")
@@ -45,29 +49,35 @@ module Arel
     end
 
     def selects
-      externalize(relation1).selects + externalize(relation2).selects
+      (externalize(relation1).selects + externalize(relation2).selects).collect { |s| s.bind(self) }
     end
    
-    def table_sql
-      externalize(relation1).table_sql
+    def table_sql(formatter = Sql::TableReference.new(engine))
+      externalize(relation1).table_sql(formatter)
+    end
+    
+    def name_for(relation)
+      @used_names ||= Hash.new(0)
+      @relation_names ||= Hash.new do |h, k|
+        @used_names[k.name] += 1
+        h[k] = k.name + (@used_names[k.name] > 1 ? "_#{@used_names[k.name]}" : '')
+      end
+      @relation_names[relation]
     end
     
     private
     def externalize(relation)
-      Externalizer.new(relation)
+      Externalizer.new(self, relation)
     end
     
-    Externalizer = Struct.new(:relation) do
+    Externalizer = Struct.new(:christener, :relation) do
       delegate :engine, :to => :relation
       
-      def table_sql
-        case
-        when relation.aggregation?
-          relation.to_sql(Sql::TableReference.new(engine))
-        when relation.alias?
-          relation.table_sql + ' AS ' + engine.quote_table_name(relation.alias.to_s)
+      def table_sql(formatter = Sql::TableReference.new(engine))
+        if relation.aggregation?
+          relation.to_sql(formatter) + ' AS ' + engine.quote_table_name(christener.name_for(relation))
         else
-          relation.table_sql
+          relation.table_sql(formatter) + (relation.name != christener.name_for(relation) ? " AS " + engine.quote_table_name(christener.name_for(relation)) : '')
         end
       end
       
@@ -78,12 +88,6 @@ module Arel
       def attributes
         relation.aggregation?? relation.attributes.collect(&:to_attribute) : relation.attributes
       end
-      
-      def prefix_for(attribute)
-        if relation[attribute]
-          relation.alias?? relation.alias : relation.prefix_for(attribute)
-        end
-      end
     end
   end
 end
\ No newline at end of file
diff --git a/lib/arel/relations/nil.rb b/lib/arel/relations/nil.rb
index 3c1d413953..67eb2d3a62 100644
--- a/lib/arel/relations/nil.rb
+++ b/lib/arel/relations/nil.rb
@@ -1,7 +1,7 @@
 module Arel
   class Nil < Relation
-    def table_sql; '' end
-    
+    def table_sql(formatter = nil); '' end
+    def name; '' end
     def to_s; '' end
     
     def ==(other)
diff --git a/lib/arel/relations/relation.rb b/lib/arel/relations/relation.rb
index 3bd40e8f6b..0a5bf2ff24 100644
--- a/lib/arel/relations/relation.rb
+++ b/lib/arel/relations/relation.rb
@@ -103,6 +103,10 @@ module Arel
       def alias?
         false
       end
+      
+      def relation_for(attribute)
+        self[attribute] and self
+      end
     end
     include Externalizable
     
@@ -116,7 +120,7 @@ module Arel
         ("GROUP BY  #{groupings.collect(&:to_sql)}"                                                     unless groupings.blank? ),
         ("LIMIT     #{taken}"                                                                           unless taken.blank?     ),
         ("OFFSET    #{skipped}"                                                                         unless skipped.blank?   )
-      ].compact.join("\n"), self.alias
+      ].compact.join("\n")
     end
     alias_method :to_s, :to_sql
     
diff --git a/lib/arel/relations/table.rb b/lib/arel/relations/table.rb
index b627558caf..7637a471bf 100644
--- a/lib/arel/relations/table.rb
+++ b/lib/arel/relations/table.rb
@@ -36,8 +36,8 @@ module Arel
       @attributes = @columns = nil
     end
 
-    def table_sql
-      engine.quote_table_name(name)
+    def table_sql(formatter = Sql::TableReference.new(engine))
+      formatter.table name
     end
   end
 end
\ No newline at end of file