Add support for virtual depth column

still need to consider whether to keep depth_cache_column as deprecated

lib/ancestry/has_ancestry.rb

@@ -64,7 +64,11 @@ def has_ancestry options = {}
       end
 
       # Create ancestry column accessor and set to option or default
-      if options[:cache_depth]
+
+      if options[:cache_depth] == :virtual
+        # NOTE: not setting self.depth_cache_column so the code does not try to update the column
+        depth_cache_sql = options[:depth_cache_column]&.to_s || 'ancestry_depth'
+      elsif options[:cache_depth]
         # Create accessor for column name and set to option or default
         self.cattr_accessor :depth_cache_column
         self.depth_cache_column =

test/environment.rb

@@ -126,7 +126,20 @@ def self.with_model options = {}
 
     ActiveRecord::Base.connection.create_table 'test_nodes', **table_options do |table|
       table.send(column_type, options[:ancestry_column], **column_options(force_allow_nil: skip_ancestry))
-      table.integer options[:cache_depth] == true ? :ancestry_depth : options[:cache_depth] if options[:cache_depth]
+      case options[:cache_depth]
+      when true
+        table.integer :ancestry_depth
+      when :virtual
+        # sorry, this duplicates has_ancestry a little
+        path_module = Ancestry::HasAncestry.ancestry_format_module(options[:ancestry_format])
+        ancestry_depth_sql = path_module.construct_depth_sql("test_nodes", options[:ancestry_column], '/')
+
+        table.virtual :ancestry_depth, type: :integer, as: ancestry_depth_sql, stored: true
+      when nil, false
+        # no column
+      else
+        table.integer options[:cache_depth]
+      end
       if options[:counter_cache]
         counter_cache_column = options[:counter_cache] == true ? :children_count : options[:counter_cache]
         table.integer counter_cache_column, default: 0, null: false