Adds support for horizontally sharded database projects (#1079)

* take a configurable base class

* make base_class instance method

* adds tests

* adds initializer install rake task

* better base_class default

* more sensible default initializer

* add sensible tests

* reduce test overhead

* updates changelog

* make base_class= simpler

* improve test clarity

* original default class

CHANGELOG.md

@@ -13,6 +13,7 @@ As such, _Breaking Changes_ are major. _Features_ would map to either major or m
 ### [v9.0.2) / unreleased](https://github.com/mbleigh/acts-as-taggable-on/compare/v9.0.1...master)
 * Features
   * [@glampr Add support for prefix and suffix searches alongside previously supported containment (wildcard) searches](https://github.com/mbleigh/acts-as-taggable-on/pull/1082)
+  * [@donquxiote Add support for horizontally sharded databases](https://github.com/mbleigh/acts-as-taggable-on/pull/1079)
 
 ### [v9.0.1) / 2022-01-07](https://github.com/mbleigh/acts-as-taggable-on/compare/v9.0.0..v9.0.1)
 * Fixes

lib/acts-as-taggable-on.rb

@@ -66,7 +66,7 @@ class Configuration
                   :remove_unused_tags, :default_parser,
                   :tags_counter, :tags_table,
                   :taggings_table
-    attr_reader :delimiter, :strict_case_match
+    attr_reader :delimiter, :strict_case_match, :base_class
 
     def initialize
       @delimiter = ','
@@ -79,6 +79,7 @@ def initialize
       @force_binary_collation = false
       @tags_table = :tags
       @taggings_table = :taggings
+      @base_class = ::ActiveRecord::Base
     end
 
     def strict_case_match=(force_cs)
@@ -119,6 +120,11 @@ def self.apply_binary_collation(bincoll)
       end
     end
 
+    def base_class=(base_class)
+      raise "base_class must be a class constant" unless base_class.is_a?(Class)
+      @base_class = base_class
+    end
+
   end
 
   setup

lib/acts_as_taggable_on/tag.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 module ActsAsTaggableOn
-  class Tag < ::ActiveRecord::Base
+  class Tag < ActsAsTaggableOn.base_class
     self.table_name = ActsAsTaggableOn.tags_table
 
     ### ASSOCIATIONS:

lib/acts_as_taggable_on/tagging.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 module ActsAsTaggableOn
-  class Tagging < ::ActiveRecord::Base # :nodoc:
+  class Tagging < ActsAsTaggableOn.base_class # :nodoc:
     self.table_name = ActsAsTaggableOn.taggings_table
 
     DEFAULT_CONTEXT = 'tags'

lib/tasks/example/acts_as_taggable_on.rb.example

@@ -0,0 +1,4 @@
+# This works because the classes where the base class is a concern, Tag and Tagging
+# are autoloaded, and won't be started until after the initializers run.
+
+# ActsAsTaggableOn.base_class = ApplicationRecord

lib/tasks/install_initializer.rake

@@ -0,0 +1,23 @@
+namespace :acts_as_taggable_on do
+
+  namespace :sharded_db do
+
+    desc "Install initializer setting custom base class"
+    task :install_initializer => [:environment, "config/initializers/foo"] do
+      source = File.join(
+        Gem.loaded_specs["acts-as-taggable-on"].full_gem_path,
+        "lib",
+        "tasks",
+        "examples",
+        "acts_as_taggable_on.rb.example"
+      )
+
+      destination = "config/initializers/acts_as_taggable_on.rb"
+
+      cp source, destination
+    end
+
+    directory "config/initializers"
+  end
+
+end

spec/acts_as_taggable_on/tag_spec.rb

@@ -352,4 +352,28 @@
     end
   end
 
+  describe 'base_class' do
+    before do
+      class Foo < ActiveRecord::Base; end
+    end
+
+    context "default" do
+      it "inherits from ActiveRecord::Base" do
+
+        expect(ActsAsTaggableOn::Tag.ancestors).to include(ActiveRecord::Base)
+        expect(ActsAsTaggableOn::Tag.ancestors).to_not include(Foo)
+      end
+    end
+
+    context "custom" do
+      it "inherits from custom class" do
+
+        ActsAsTaggableOn.base_class = Foo
+        hide_const("ActsAsTaggableOn::Tag")
+        load("lib/acts_as_taggable_on/tag.rb")
+
+        expect(ActsAsTaggableOn::Tag.ancestors).to include(Foo)
+      end
+    end
+  end
 end

spec/acts_as_taggable_on/tagging_spec.rb

@@ -140,4 +140,30 @@
       end
     end
   end
+
+  describe 'base_class' do
+    before do
+      class Foo < ActiveRecord::Base; end
+    end
+
+    context "default" do
+      it "inherits from ActiveRecord::Base" do
+
+        expect(ActsAsTaggableOn::Tagging.ancestors).to include(ActiveRecord::Base)
+        expect(ActsAsTaggableOn::Tagging.ancestors).to_not include(Foo)
+      end
+    end
+
+    context "custom" do
+      it "inherits from custom class" do
+
+        ActsAsTaggableOn.base_class = Foo
+        hide_const("ActsAsTaggableOn::Tagging")
+        load("lib/acts_as_taggable_on/tagging.rb")
+
+        expect(ActsAsTaggableOn::Tagging.ancestors).to include(Foo)
+      end
+    end
+  end
+
 end