delete manager added

8 files changed, 117 insertions, 0 deletions

diff --git a/lib/arel.rb b/lib/arel.rb
index acb270728f..0d03d0a4bb 100644
--- a/lib/arel.rb
+++ b/lib/arel.rb
@@ -14,6 +14,7 @@ require 'arel/tree_manager'
 require 'arel/insert_manager'
 require 'arel/select_manager'
 require 'arel/update_manager'
+require 'arel/delete_manager'
 require 'arel/nodes'
 
 #### these are deprecated
diff --git a/lib/arel/crud.rb b/lib/arel/crud.rb
index 7f78acef84..6861ff016c 100644
--- a/lib/arel/crud.rb
+++ b/lib/arel/crud.rb
@@ -22,5 +22,12 @@ module Arel
       im.insert values
       @engine.connection.execute im.to_sql
     end
+
+    def delete
+      dm = DeleteManager.new @engine
+      dm.wheres = @ctx.wheres
+      dm.from @ctx.froms.last
+      @engine.connection.execute dm.to_sql
+    end
   end
 end
diff --git a/lib/arel/delete_manager.rb b/lib/arel/delete_manager.rb
new file mode 100644
index 0000000000..4759f116f1
--- /dev/null
+++ b/lib/arel/delete_manager.rb
@@ -0,0 +1,22 @@
+module Arel
+  class DeleteManager < Arel::TreeManager
+    def initialize engine
+      super
+      @head = Nodes::DeleteStatement.new
+    end
+
+    def from relation
+      @head.relation = relation
+      self
+    end
+
+    def where expression
+      @head.wheres << expression
+      self
+    end
+
+    def wheres= list
+      @head.wheres = list
+    end
+  end
+end
diff --git a/lib/arel/nodes.rb b/lib/arel/nodes.rb
index bf144ecaf8..4d6db39aec 100644
--- a/lib/arel/nodes.rb
+++ b/lib/arel/nodes.rb
@@ -8,4 +8,5 @@ require 'arel/nodes/select_core'
 require 'arel/nodes/select_statement'
 require 'arel/nodes/insert_statement'
 require 'arel/nodes/update_statement'
+require 'arel/nodes/delete_statement'
 require 'arel/nodes/unqualified_column'
diff --git a/lib/arel/nodes/delete_statement.rb b/lib/arel/nodes/delete_statement.rb
new file mode 100644
index 0000000000..54bf513c2b
--- /dev/null
+++ b/lib/arel/nodes/delete_statement.rb
@@ -0,0 +1,12 @@
+module Arel
+  module Nodes
+    class DeleteStatement
+      attr_accessor :relation, :wheres
+
+      def initialize
+        @from   = nil
+        @wheres = []
+      end
+    end
+  end
+end
diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
index fd467495ae..0e5998c573 100644
--- a/lib/arel/visitors/to_sql.rb
+++ b/lib/arel/visitors/to_sql.rb
@@ -12,6 +12,13 @@ module Arel
       end
 
       private
+      def visit_Arel_Nodes_DeleteStatement o
+        [
+          "DELETE FROM #{visit o.relation}",
+          ("WHERE #{o.wheres.map { |x| visit x }.join ' AND '}" unless o.wheres.empty?)
+        ].compact.join ' '
+      end
+
       def visit_Arel_Nodes_UpdateStatement o
         [
           "UPDATE #{visit o.relation}",
diff --git a/spec/arel/delete_manager_spec.rb b/spec/arel/delete_manager_spec.rb
new file mode 100644
index 0000000000..88d4df061a
--- /dev/null
+++ b/spec/arel/delete_manager_spec.rb
@@ -0,0 +1,42 @@
+require 'spec_helper'
+
+module Arel
+  describe 'delete manager' do
+    describe 'new' do
+      it 'takes an engine' do
+        Arel::DeleteManager.new Table.engine
+      end
+    end
+
+    describe 'from' do
+      it 'uses from' do
+        table = Table.new(:users)
+        dm = Arel::DeleteManager.new Table.engine
+        dm.from table
+        dm.to_sql.should be_like %{ DELETE FROM "users" }
+      end
+
+      it 'chains' do
+        table = Table.new(:users)
+        dm = Arel::DeleteManager.new Table.engine
+        check dm.from(table).should == dm
+      end
+    end
+
+    describe 'where' do
+      it 'uses where values' do
+        table = Table.new(:users)
+        dm = Arel::DeleteManager.new Table.engine
+        dm.from table
+        dm.where table[:id].eq(10)
+        dm.to_sql.should be_like %{ DELETE FROM "users" WHERE "users"."id" = 10}
+      end
+
+      it 'chains' do
+        table = Table.new(:users)
+        dm = Arel::DeleteManager.new Table.engine
+        check dm.where(table[:id].eq(10)).should == dm
+      end
+    end
+  end
+end
diff --git a/spec/arel/select_manager_spec.rb b/spec/arel/select_manager_spec.rb
index a728366e0e..01d1b35004 100644
--- a/spec/arel/select_manager_spec.rb
+++ b/spec/arel/select_manager_spec.rb
@@ -23,6 +23,31 @@ module Arel
   end
 
   describe 'select manager' do
+    describe 'delete' do
+      it "copies from" do
+        engine  = EngineProxy.new Table.engine
+        table   = Table.new :users
+        manager = Arel::SelectManager.new engine
+        manager.from table
+        manager.delete
+
+        engine.executed.last.should be_like %{ DELETE FROM "users" }
+      end
+
+      it "copies where" do
+        engine  = EngineProxy.new Table.engine
+        table   = Table.new :users
+        manager = Arel::SelectManager.new engine
+        manager.from table
+        manager.where table[:id].eq 10
+        manager.delete
+
+        engine.executed.last.should be_like %{
+          DELETE FROM "users" WHERE "users"."id" = 10
+        }
+      end
+    end
+
     describe 'update' do
       it 'takes a string' do
         engine  = EngineProxy.new Table.engine