Merge pull request #663 from kbrock/child_ancestry_sql

rebuild_counter_cache

lib/ancestry/class_methods.rb

@@ -225,10 +225,35 @@ def rebuild_depth_cache!
       end
     end
 
+    # NOTE: this is temporarily kept separate from rebuild_depth_cache!
+    # this will become the implementation of rebuild_depth_cache!
     def rebuild_depth_cache_sql!
       update_all("#{depth_cache_column} = #{ancestry_depth_sql}")
     end
 
+    def rebuild_counter_cache!
+     if %w(mysql mysql2).include?(connection.adapter_name.downcase)
+        connection.execute %{
+          UPDATE #{table_name} AS dest
+          LEFT JOIN (
+            SELECT #{table_name}.#{primary_key}, COUNT(*) AS child_count
+            FROM #{table_name}
+            JOIN #{table_name} children ON children.#{ancestry_column} = (#{child_ancestry_sql})
+            GROUP BY #{table_name}.#{primary_key}
+          ) src USING(#{primary_key})
+          SET dest.#{counter_cache_column} = src.child_count
+        }
+      else
+        update_all %{
+          #{counter_cache_column} = (
+            SELECT COUNT(*)
+            FROM #{table_name} children
+            WHERE children.#{ancestry_column} = (#{child_ancestry_sql})
+          )
+        }
+      end
+    end
+
     def unscoped_where
       yield ancestry_base_class.default_scoped.unscope(:where)
     end

lib/ancestry/materialized_path.rb

@@ -92,6 +92,14 @@ def ancestry_root
       nil
     end
 
+    def child_ancestry_sql
+      %{
+        CASE WHEN #{table_name}.#{ancestry_column} IS NULL THEN CAST(#{table_name}.#{primary_key} AS CHAR)
+        ELSE      #{concat("#{table_name}.#{ancestry_column}", "'#{ancestry_delimiter}'", "CAST(#{table_name}.#{primary_key} AS CHAR)")}
+        END
+      }
+    end
+
     def ancestry_depth_sql
       @ancestry_depth_sql ||=
         begin
@@ -119,6 +127,14 @@ def ancestry_depth_change(old_value, new_value)
       parse_ancestry_column(new_value).size - parse_ancestry_column(old_value).size
     end
 
+    def concat(*args)
+      if %w(sqlite sqlite3).include?(connection.adapter_name.downcase)
+        args.join('||')
+      else
+        %{CONCAT(#{args.join(', ')})}
+      end
+    end
+
     private
 
     def ancestry_validation_options(ancestry_primary_key_format)

lib/ancestry/materialized_path2.rb

@@ -28,6 +28,10 @@ def ancestry_root
       ancestry_delimiter
     end
 
+    def child_ancestry_sql
+      concat("#{table_name}.#{ancestry_column}", "CAST(#{table_name}.#{primary_key} AS CHAR)", "'#{ancestry_delimiter}'")
+    end
+
     def ancestry_depth_sql
       @ancestry_depth_sql ||=
         begin

test/concerns/counter_cache_test.rb

@@ -86,4 +86,19 @@ def test_counter_cache_when_updating_record
       end
     end
   end
+
+  def test_setting_counter_cache
+    AncestryTestDatabase.with_model :depth => 2, :width => 2, :counter_cache => true do |model, roots|
+      model.update_all(model.counter_cache_column => 0)
+      # ensure they are successfully broken
+      roots.each do |lvl0_node, _lvl0_children|
+        assert_equal 0, lvl0_node.reload.children_count
+      end
+      model.rebuild_counter_cache!
+      # ensure they are successfully built
+      roots.each do |lvl0_node, _lvl0_children|
+        assert_equal 2, lvl0_node.reload.children_count
+      end
+    end
+  end
 end

test/concerns/depth_caching_test.rb

@@ -75,8 +75,6 @@ def test_rebuild_depth_cache_with_sql
       end
 
       # Rebuild cache
-      # require "byebug"
-      # byebug
       model.rebuild_depth_cache_sql!
 
       # Assert cache was rebuild correctly