First commit

.gitignore

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+/.bundle/
+/.yardoc
+/_yardoc/
+/coverage/
+/doc/
+/pkg/
+/spec/reports/
+/tmp/
+*.lock

CHANGELOG.md

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+## 0.0.1
+
+- First release

Gemfile

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+source "https://rubygems.org"
+
+# Specify your gem's dependencies in multiverse.gemspec
+gemspec

LICENSE.txt

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+Copyright (c) 2017 Andrew Kane
+
+MIT License
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+# Multiverse
+
+:fire: Multiple databases for Rails
+
+One of the easiest ways to scale your database is to move large, infrequently-joined tables to a separate database. **ActiveRecord supports multiple databases, but Rails doesn’t provide a way to manage them.** Multiverse changes this.
+
+Works with Rails 5+
+
+## Installation
+
+Add this line to your application’s Gemfile:
+
+```ruby
+gem 'multiverse'
+```
+
+## Getting Started
+
+Generate a new database
+
+```sh
+rails generate multiverse:db catalog
+```
+
+This generates `CatalogRecord` class for models to inherit from and adds configuration to `config/database.yml`. It also creates a `db/catalog` directory for migrations and `schema.rb` to live.
+
+`rails` and `rake` commands will run for the original database by default. To run commands for the new database, use the `DB` environment variable. For instance:
+
+Create the database
+
+```sh
+DB=catalog rake db:create
+```
+
+Create a migration
+
+```sh
+DB=catalog rails generate migration add_name_to_products
+```
+
+Run migrations
+
+```sh
+DB=catalog rake db:migrate
+```
+
+Rollback
+
+```sh
+DB=catalog rake db:rollback
+```
+
+## Models
+
+Also works for models
+
+```sh
+DB=catalog rails generate model Product
+```
+
+This generates
+
+```rb
+class Product < CatalogRecord
+end
+```
+
+## Seeds
+
+Use `db/seeds.rb` for all databases
+
+## Web Servers
+
+### Puma
+
+Add to `config/puma.rb`
+
+```ruby
+on_worker_boot do
+  CatalogRecord.establish_connection :"catalog_#{Rails.env}"
+end
+```
+
+### Unicorn
+
+Add to `config/unicorn.rb`
+
+```ruby
+before_fork do |server, worker|
+  CatalogRecord.connection.disconnect!
+end
+
+after_fork do |server, worker|
+  CatalogRecord.establish_connection :"catalog_#{Rails.env}"
+end
+```
+
+## History
+
+View the [changelog](https://github.com/ankane/multiverse/blob/master/CHANGELOG.md)
+
+## Contributing
+
+Everyone is encouraged to help improve this project. Here are a few ways you can help:
+
+- [Report bugs](https://github.com/ankane/multiverse/issues)
+- Fix bugs and [submit pull requests](https://github.com/ankane/multiverse/pulls)
+- Write, clarify, or fix documentation
+- Suggest or add new features

Rakefile

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+require "bundler/gem_tasks"
+require "rake/testtask"
+
+Rake::TestTask.new(:test) do |t|
+  t.libs << "test"
+  t.libs << "lib"
+  t.test_files = FileList["test/**/*_test.rb"]
+end
+
+task :default => :test

lib/generators/multiverse/db_generator.rb

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+require "rails/generators"
+
+module Multiverse
+  module Generators
+    class DbGenerator < Rails::Generators::Base
+      source_root File.expand_path("../templates", __FILE__)
+
+      argument :name
+
+      def create_initializer
+        lower_name = name.underscore
+
+        template "record.rb", "app/models/#{lower_name}_record.rb"
+
+        append_to_file "config/database.yml" do
+          "
+#{name}_development:
+  <<: *default
+  database: #{lower_name}_development
+
+#{name}_test:
+  <<: *default
+  database: #{lower_name}_test
+
+#{name}_production:
+  <<: *default
+  url: <%= ENV['#{lower_name.upcase}_DATABASE_URL'] %>
+"
+        end
+
+        empty_directory "db/#{lower_name}/migrate"
+      end
+    end
+  end
+end

lib/generators/multiverse/templates/record.rb

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+class <%= name.camelize %>Record < ActiveRecord::Base
+  self.abstract_class = true
+  establish_connection :"<%= name.underscore %>_#{Rails.env}"
+end

lib/multiverse.rb

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+require "multiverse/generators"
+require "multiverse/patches"
+require "multiverse/railtie"
+require "multiverse/version"
+
+module Multiverse
+  class << self
+    attr_writer :db
+
+    def db
+      @db ||= ENV["DB"]
+    end
+
+    def db_dir
+      db_dir = db ? "db/#{db}" : "db"
+      abort "Unknown DB: #{db}" if db && !Dir.exist?(db_dir)
+      db_dir
+    end
+
+    def parent_class_name
+      db ? "#{db.camelize}Record" : "ApplicationRecord"
+    end
+
+    def record_class
+      record_class = parent_class_name.safe_constantize
+      abort "Missing model: #{parent_class_name}" unless record_class
+      record_class
+    end
+
+    def migrate_path
+      "#{db_dir}/migrate"
+    end
+  end
+end
+
+ActiveSupport.on_load(:active_record) do
+  ActiveRecord::Tasks::DatabaseTasks.singleton_class.prepend Multiverse::DatabaseTasks
+  ActiveRecord::Migration.prepend Multiverse::Migration
+  ActiveRecord::SchemaMigration.singleton_class.prepend Multiverse::SchemaMigration
+  ActiveRecord::SchemaDumper.singleton_class.prepend Multiverse::SchemaDumper
+end

lib/multiverse/generators.rb

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+module Multiverse
+  module Generators
+    module ModelGenerator
+      def parent_class_name
+        Multiverse.parent_class_name
+      end
+    end
+
+    module Migration
+      def db_migrate_path
+        Multiverse.migrate_path
+      end
+    end
+  end
+end

lib/multiverse/patches.rb

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+module Multiverse
+  module DatabaseTasks
+    def each_current_configuration(environment)
+      if Multiverse.db
+        environments = ["#{Multiverse.db}_#{environment}"]
+        environments << "#{Multiverse.db}_test" if environment == "development"
+        self.migrations_paths = Multiverse.migrate_path
+        self.db_dir = Multiverse.db_dir
+      else
+        environments = [environment]
+        environments << "test" if environment == "development"
+      end
+
+      configurations = ActiveRecord::Base.configurations.values_at(*environments)
+      configurations.compact.each do |configuration|
+        yield configuration unless configuration['database'].blank?
+      end
+    end
+  end
+
+  module Migration
+    def connection
+      @connection || Multiverse.record_class.connection
+    end
+
+    # TODO don't checkout main connection at all
+    def exec_migration(_, direction)
+      Multiverse.record_class.connection_pool.with_connection do |conn|
+        super(conn, direction)
+      end
+    end
+  end
+
+  module SchemaMigration
+    def connection
+      Multiverse.record_class.connection
+    end
+  end
+
+  module SchemaDumper
+    def dump(connection = ActiveRecord::Base.connection, stream = STDOUT, config = ActiveRecord::Base)
+      new(Multiverse.record_class.connection, generate_options(Multiverse.record_class)).dump(stream)
+      stream
+    end
+  end
+end

lib/multiverse/railtie.rb

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+require "rails/railtie"
+
+module Multiverse
+  class Railtie < Rails::Railtie
+    generators do
+      require "rails/generators/active_record/migration"
+      ActiveRecord::Generators::Migration.prepend(Multiverse::Generators::Migration)
+
+      require "rails/generators/active_record/model/model_generator"
+      ActiveRecord::Generators::ModelGenerator.prepend(Multiverse::Generators::ModelGenerator)
+    end
+
+    rake_tasks do
+      namespace :db do
+        task :load_config do
+          ActiveRecord::Tasks::DatabaseTasks.migrations_paths = [Multiverse.migrate_path]
+          ActiveRecord::Tasks::DatabaseTasks.db_dir = [Multiverse.db_dir]
+        end
+      end
+    end
+  end
+end

lib/multiverse/version.rb

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+module Multiverse
+  VERSION = "0.0.1"
+end

multiverse.gemspec

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+
+lib = File.expand_path("../lib", __FILE__)
+$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
+require "multiverse/version"
+
+Gem::Specification.new do |spec|
+  spec.name          = "multiverse"
+  spec.version       = Multiverse::VERSION
+  spec.authors       = ["Andrew Kane"]
+  spec.email         = ["andrew@chartkick.com"]
+
+  spec.summary       = "Multiple databases for Rails"
+  spec.homepage      = "https://github.com/ankane/multiverse"
+
+  spec.files         = `git ls-files -z`.split("\x0").reject do |f|
+    f.match(%r{^(test|spec|features)/})
+  end
+  spec.bindir        = "exe"
+  spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
+  spec.require_paths = ["lib"]
+
+  spec.add_dependency "rails", ">= 5"
+
+  spec.add_development_dependency "bundler"
+  spec.add_development_dependency "rake"
+  spec.add_development_dependency "minitest"
+end

test/multiverse_test.rb

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+require_relative "test_helper"
+
+class MultiverseTest < Minitest::Test
+  def test_that_it_has_a_version_number
+    refute_nil ::Multiverse::VERSION
+  end
+end

test/test_helper.rb

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+require "bundler/setup"
+Bundler.require(:default)
+require "minitest/autorun"
+require "minitest/pride"