Extracting #build_query method for creating SQL from parts

3 files changed, 25 insertions, 16 deletions

diff --git a/lib/arel/engines/sql/relations/relation.rb b/lib/arel/engines/sql/relations/relation.rb
index c8a4d952fe..4cfb83a601 100644
--- a/lib/arel/engines/sql/relations/relation.rb
+++ b/lib/arel/engines/sql/relations/relation.rb
@@ -5,7 +5,7 @@ module Arel
     end
 
     def select_sql
-      [
+      build_query \
         "SELECT     #{select_clauses.join(', ')}",
         "FROM       #{table_sql(Sql::TableReference.new(self))}",
         (joins(self)                                   unless joins(self).blank? ),
@@ -14,10 +14,8 @@ module Arel
         ("ORDER BY  #{order_clauses.join(', ')}"       unless orders.blank?      ),
         ("LIMIT     #{taken}"                          unless taken.blank?       ),
         ("OFFSET    #{skipped}"                        unless skipped.blank?     )
-      ].compact.join("\n")
     end
 
-
     def inclusion_predicate_sql
       "IN"
     end
@@ -28,6 +26,10 @@ module Arel
 
   protected
 
+    def build_query(*parts)
+      parts.compact.join("\n")
+    end
+
     def select_clauses
       attributes.collect { |a| a.to_sql(Sql::SelectClause.new(self)) }
     end
diff --git a/lib/arel/engines/sql/relations/utilities/compound.rb b/lib/arel/engines/sql/relations/utilities/compound.rb
index b63a829c67..f8ce4033fd 100644
--- a/lib/arel/engines/sql/relations/utilities/compound.rb
+++ b/lib/arel/engines/sql/relations/utilities/compound.rb
@@ -1,6 +1,10 @@
 module Arel
   class Compound < Relation
     delegate :table, :table_sql, :to => :relation
+
+    def build_query(*parts)
+      parts.compact.join("\n")
+    end
   end
 end
 
diff --git a/lib/arel/engines/sql/relations/writes.rb b/lib/arel/engines/sql/relations/writes.rb
index 4d753f5fca..f1a9bfd2ac 100644
--- a/lib/arel/engines/sql/relations/writes.rb
+++ b/lib/arel/engines/sql/relations/writes.rb
@@ -1,36 +1,39 @@
 module Arel
   class Deletion < Compound
     def to_sql(formatter = nil)
-      [
+      build_query \
         "DELETE",
         "FROM #{table_sql}",
-        ("WHERE #{wheres.collect(&:to_sql).join('\n\tAND ')}" unless wheres.blank?  ),
-        ("LIMIT #{taken}"                                     unless taken.blank?    ),
-      ].compact.join("\n")
+        ("WHERE #{wheres.collect(&:to_sql).join('\n\tAND ')}" unless wheres.blank? ),
+        ("LIMIT #{taken}"                                     unless taken.blank?  )
     end
   end
 
   class Insert < Compound
     def to_sql(formatter = nil)
-      [
+      build_query \
         "INSERT",
         "INTO #{table_sql}",
         "(#{record.keys.collect { |key| engine.quote_column_name(key.name) }.join(', ')})",
         "VALUES (#{record.collect { |key, value| key.format(value) }.join(', ')})"
-      ].join("\n")
     end
   end
 
   class Update < Compound
     def to_sql(formatter = nil)
-      [
+      build_query \
         "UPDATE #{table_sql} SET",
-        assignments.collect do |attribute, value|
-          "#{engine.quote_column_name(attribute.name)} = #{attribute.format(value)}"
-        end.join(",\n"),
-        ("WHERE #{wheres.collect(&:to_sql).join('\n\tAND ')}"  unless wheres.blank?  ),
-        ("LIMIT #{taken}"                                      unless taken.blank?    )
-      ].join("\n")
+        assignment_sql,
+        ("WHERE #{wheres.collect(&:to_sql).join('\n\tAND ')}"  unless wheres.blank? ),
+        ("LIMIT #{taken}"                                      unless taken.blank?  )
+    end
+
+  protected
+
+    def assignment_sql
+      assignments.collect do |attribute, value|
+        "#{engine.quote_column_name(attribute.name)} = #{attribute.format(value)}"
+      end.join(",\n")
     end
   end
 end