Merge pull request #410 from kbrock/concat

Add database specific string concatenation

8 files changed, 47 insertions, 3 deletions

diff --git a/lib/arel/nodes/infix_operation.rb b/lib/arel/nodes/infix_operation.rb
index 3911a1e05e..a3f04da6fa 100644
--- a/lib/arel/nodes/infix_operation.rb
+++ b/lib/arel/nodes/infix_operation.rb
@@ -40,5 +40,10 @@ module Arel
       end
     end
 
+    class Concat < InfixOperation
+      def initialize left, right
+        super('||', left, right)
+      end
+    end
   end
-end
\ No newline at end of file
+end
diff --git a/lib/arel/predications.rb b/lib/arel/predications.rb
index e9078e9c4b..81bf3b4d95 100644
--- a/lib/arel/predications.rb
+++ b/lib/arel/predications.rb
@@ -202,6 +202,10 @@ Passing a range to `#not_in` is deprecated. Call `#not_between`, instead.
       Nodes::Case.new(self).when quoted_node(right)
     end
 
+    def concat other
+      Nodes::Concat.new self, other
+    end
+
     private
 
     def grouping_any method_id, others, *extras
diff --git a/lib/arel/visitors/depth_first.rb b/lib/arel/visitors/depth_first.rb
index 2f71455580..fb21fb1e70 100644
--- a/lib/arel/visitors/depth_first.rb
+++ b/lib/arel/visitors/depth_first.rb
@@ -72,6 +72,7 @@ module Arel
       alias :visit_Arel_Nodes_As                 :binary
       alias :visit_Arel_Nodes_Assignment         :binary
       alias :visit_Arel_Nodes_Between            :binary
+      alias :visit_Arel_Nodes_Concat             :binary
       alias :visit_Arel_Nodes_DeleteStatement    :binary
       alias :visit_Arel_Nodes_DoesNotMatch       :binary
       alias :visit_Arel_Nodes_Equality           :binary
diff --git a/lib/arel/visitors/dot.rb b/lib/arel/visitors/dot.rb
index e0c02d717a..da75423523 100644
--- a/lib/arel/visitors/dot.rb
+++ b/lib/arel/visitors/dot.rb
@@ -176,6 +176,7 @@ module Arel
       alias :visit_Arel_Nodes_As                 :binary
       alias :visit_Arel_Nodes_Assignment         :binary
       alias :visit_Arel_Nodes_Between            :binary
+      alias :visit_Arel_Nodes_Concat             :binary
       alias :visit_Arel_Nodes_DoesNotMatch       :binary
       alias :visit_Arel_Nodes_Equality           :binary
       alias :visit_Arel_Nodes_GreaterThan        :binary
diff --git a/lib/arel/visitors/mysql.rb b/lib/arel/visitors/mysql.rb
index 724e0fc43e..ac3ad7b470 100644
--- a/lib/arel/visitors/mysql.rb
+++ b/lib/arel/visitors/mysql.rb
@@ -72,6 +72,14 @@ module Arel
         maybe_visit o.limit, collector
       end
 
+      def visit_Arel_Nodes_Concat o, collector
+        collector << " CONCAT("
+        visit o.left, collector
+        collector << ", "
+        visit o.right, collector
+        collector << ") "
+        collector
+      end
     end
   end
 end
diff --git a/test/visitors/test_depth_first.rb b/test/visitors/test_depth_first.rb
index 1a72789f83..81220b63a4 100644
--- a/test/visitors/test_depth_first.rb
+++ b/test/visitors/test_depth_first.rb
@@ -103,6 +103,7 @@ module Arel
       [
         Arel::Nodes::Assignment,
         Arel::Nodes::Between,
+        Arel::Nodes::Concat,
         Arel::Nodes::DoesNotMatch,
         Arel::Nodes::Equality,
         Arel::Nodes::GreaterThan,
diff --git a/test/visitors/test_mysql.rb b/test/visitors/test_mysql.rb
index 8e4b9e6861..30dcea3d36 100644
--- a/test/visitors/test_mysql.rb
+++ b/test/visitors/test_mysql.rb
@@ -55,6 +55,24 @@ module Arel
           compile(node).must_be_like "LOCK IN SHARE MODE"
         end
       end
+
+      describe "concat" do
+        it "concats columns" do
+          @table = Table.new(:users)
+          query = @table[:name].concat(@table[:name])
+          compile(query).must_be_like %{
+            CONCAT("users"."name", "users"."name")
+          }
+        end
+
+        it "concats a string" do
+          @table = Table.new(:users)
+          query = @table[:name].concat(Nodes.build_quoted('abc'))
+          compile(query).must_be_like %{
+            CONCAT("users"."name", 'abc')
+          }
+        end
+      end
     end
   end
 end
diff --git a/test/visitors/test_to_sql.rb b/test/visitors/test_to_sql.rb
index ea58039529..4162d970b5 100644
--- a/test/visitors/test_to_sql.rb
+++ b/test/visitors/test_to_sql.rb
@@ -469,13 +469,19 @@ module Arel
           compile(node).must_equal %(("products"."price" - 7))
         end
 
+        it "should handle Concatination" do
+          table = Table.new(:users)
+          node = table[:name].concat(table[:name])
+          compile(node).must_equal %("users"."name" || "users"."name")
+        end
+
         it "should handle arbitrary operators" do
           node = Arel::Nodes::InfixOperation.new(
-            '||',
+            '&&',
             Arel::Attributes::String.new(Table.new(:products), :name),
             Arel::Attributes::String.new(Table.new(:products), :name)
           )
-          compile(node).must_equal %("products"."name" || "products"."name")
+          compile(node).must_equal %("products"."name" && "products"."name")
         end
       end