Merge pull request #758 from kbrock/adapter-module

Conditional SQL based upon connector (mysql/pg/sqlite)

Author: kbrock

lib/ancestry.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require_relative 'ancestry/version'
+require_relative 'ancestry/adapter'
 require_relative 'ancestry/class_methods'
 require_relative 'ancestry/instance_methods'
 require_relative 'ancestry/exceptions'

lib/ancestry/adapter.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module Ancestry
+  # Adapter detection helpers — small wrappers around the connection's
+  # adapter_name. Centralizes the magic strings so format modules and
+  # other call sites stop duplicating the matcher arrays.
+  module Adapter
+    extend self
+
+    PG     = %w(pg postgresql postgis).freeze
+    MYSQL  = %w(mysql mysql2 trilogy).freeze
+    SQLITE = %w(sqlite sqlite3).freeze
+
+    def pg?(adapter = current)
+      PG.include?(adapter.to_s.downcase)
+    end
+
+    def mysql?(adapter = current)
+      MYSQL.include?(adapter.to_s.downcase)
+    end
+
+    def sqlite?(adapter = current)
+      SQLITE.include?(adapter.to_s.downcase)
+    end
+
+    def current
+      ActiveRecord::Base.connection.adapter_name
+    end
+
+    # Cross-DB string concatenation. SQLite uses ||; PG/MySQL use CONCAT().
+    # Returns a SQL fragment as a String — not an Arel node.
+    def concat(adapter, *args)
+      sqlite?(adapter) ? args.join('||') : "CONCAT(#{args.join(', ')})"
+    end
+  end
+end

lib/ancestry/materialized_path.rb

@@ -5,6 +5,8 @@ module Ancestry
   # root a=nil,id=1   children=id,id/%      == 1, 1/%
   # 3: a=1/2,id=3     children=a/id,a/id/%  == 1/2/3, 1/2/3/%
   class MaterializedPath
+    extend Ancestry::Adapter
+
     def self.root
       nil
     end
@@ -71,14 +73,6 @@ def self.indirects_condition(attr, child_ancestry)
       attr.matches("#{child_ancestry}/%", nil, true)
     end
 
-    def self.concat(adapter, *args)
-      if %w(sqlite sqlite3).include?(adapter)
-        args.join('||')
-      else
-        %{CONCAT(#{args.join(', ')})}
-      end
-    end
-
     # SQL to replace old ancestry prefix with new ancestry prefix in descendants
     def self.replace_ancestry_sql(column, old_ancestry, new_ancestry, klass)
       adapter = klass.connection.adapter_name.downcase

lib/ancestry/materialized_path_array.rb

@@ -5,6 +5,8 @@ module Ancestry
   # root: a=[],id=1    children=a||[id] == [1]
   # 3:    a=[1,2],id=3  children=a||[id] == [1,2,3]
   class MaterializedPathArray
+    extend Ancestry::Adapter
+
     def self.root
       []
     end