Create a specialized database configuration for tenanted: true

Author: flavorjones

GUIDE.md

@@ -50,6 +50,7 @@ Documentation:
 
 TODO:
 - implement `AR::Tenanted::DatabaseConfigurations::RootConfig` (name?)
+  - [x] create the specialized RootConfig for `tenanted: true` databases
   - [ ] `#database_path_for(tenant_name)`
   - [ ] `#tenants` returns all the tenants on disk (for iteration)
 
@@ -111,6 +112,10 @@ TODO:
     - and if not, figure out how to prune unused/timed-out connections
   - [ ] we should also look into how to cap the number of connection pools, and prune them
 
+- autoloading and configuration hooks
+  - [ ] create a zeitwerk loader
+  - [ ] install some load hooks (where?)
+
 
 ### Tenanting in your application
 

Gemfile.lock

@@ -102,6 +102,7 @@ PATH
   specs:
     active_record-tenanted (0.1.0)
       activerecord (>= 8.1.alpha)
+      railties (>= 8.1.alpha)
 
 GEM
   remote: https://rubygems.org/

active_record-tenanted.gemspec

@@ -26,5 +26,6 @@ Gem::Specification.new do |spec|
     Dir["{app,config,db,lib}/**/*", "MIT-LICENSE", "Rakefile", "README.md"]
   end
 
+  spec.add_dependency "railties", ">= 8.1.alpha"
   spec.add_dependency "activerecord", ">= 8.1.alpha"
 end

lib/active_record/tenanted.rb

@@ -1,10 +1,12 @@
 # frozen_string_literal: true
 
-require "active_record/tenanted/version"
-require "active_record/tenanted/railtie"
+require_relative "tenanted/version"
 
 module ActiveRecord
   module Tenanted
-    # Your code goes here...
   end
 end
+
+require_relative "tenanted/database_configurations"
+
+require_relative "tenanted/railtie"

lib/active_record/tenanted/database_configurations.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+require "active_record/database_configurations"
+
+module ActiveRecord
+  module Tenanted
+    module DatabaseConfigurations
+      class RootConfig < ActiveRecord::DatabaseConfigurations::HashConfig
+      end
+    end
+  end
+end

lib/active_record/tenanted/railtie.rb

@@ -6,3 +6,10 @@ class Railtie < ::Rails::Railtie
     end
   end
 end
+
+ActiveSupport.on_load(:active_record) do
+  ActiveRecord::DatabaseConfigurations.register_db_config_handler do |env_name, name, _, config|
+    next unless config.fetch(:tenanted, false)
+    ActiveRecord::Tenanted::DatabaseConfigurations::RootConfig.new(env_name, name, config)
+  end
+end

test/scenarios/vanilla/database.yml

@@ -0,0 +1,10 @@
+test:
+  isolated:
+    tenanted: true
+    adapter: "sqlite3"
+    database: "%{storage}/test/isolated/%%{tenant}/main.sqlite3"
+    migrations_paths: "%{__dir__}/%{scenario}/isolated_migrations"
+  shared:
+    adapter: "sqlite3"
+    database: "%{storage}/test/shared/%%{tenant}/main.sqlite3"
+    migrations_paths: "%{__dir__}/%{scenario}/shared_migrations"

test/test_helper.rb

@@ -4,14 +4,44 @@
 ENV["RAILS_ENV"] = "test"
 
 require "rails"
-require "rails/test_help"
+require "rails/test_help" # should be before active_record to avoid schema/fixture setup
+require "active_record"
 
 require "minitest/spec"
 
+require_relative "../lib/active_record/tenanted"
+
 module ActiveRecord
   module Tenanted
     class TestCase < ActiveSupport::TestCase
       extend Minitest::Spec::DSL
+
+      class << self
+        def for_each_db_config(&block)
+          Dir.glob("#{__dir__}/scenarios/*/database.yml").each do |db_config_path|
+            db_config_name = File.basename(File.dirname(db_config_path))
+
+            describe "#{db_config_name} db config" do
+              setup do
+                @storage = Dir.mktmpdir(db_config_name)
+                db_config_yml = sprintf(File.read(db_config_path),
+                                        __dir__: __dir__, storage: @storage, scenario: "TODO")
+                db_config = YAML.load(db_config_yml)
+
+                @old_configurations = ActiveRecord::Base.configurations
+                ActiveRecord::Base.configurations = db_config
+              end
+
+              teardown do
+                ActiveRecord::Base.configurations = @old_configurations
+                FileUtils.remove_entry @storage
+              end
+
+              instance_eval(&block)
+            end
+          end
+        end
+      end
     end
   end
 end

test/unit/database_configurations_test.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+describe ActiveRecord::Tenanted::DatabaseConfigurations do
+  for_each_db_config do
+    test "it instantiates a RootConfig for the tenanted database" do
+      config = ActiveRecord::Base.configurations.configs_for(include_hidden: true)
+
+      assert_equal(
+        {
+          "isolated" => ActiveRecord::Tenanted::DatabaseConfigurations::RootConfig,
+          "shared" => ActiveRecord::DatabaseConfigurations::HashConfig,
+        },
+        config.each_with_object({}) { |c, h| h[c.name] = c.class }
+      )
+    end
+  end
+end