From ce55df39ccbfe885fd551d0f1bd7307679bc654e Mon Sep 17 00:00:00 2001
From: Reid Morrison <reidmo@gmail.com>
Date: Thu, 17 Dec 2020 17:22:52 -0500
Subject: [PATCH 1/7] Working towards Rails 6

---
 .rubocop.yml                                  |  63 +++++
 .travis.yml                                   |  58 ++---
 Appraisals                                    |  23 +-
 Gemfile                                       |  22 +-
 README.md                                     | 225 ++++++++++--------
 Rakefile                                      |  16 +-
 active_record_replica.gemspec                 |  26 +-
 lib/active_record_replica.rb                  |  20 +-
 .../active_record_replica.rb                  |  54 +++--
 lib/active_record_replica/extensions.rb       |  52 ++--
 lib/active_record_replica/replica.rb          |   2 +
 test/database_rails6.yml                      |  23 ++
 test/test_helper.rb                           |  34 +--
 13 files changed, 385 insertions(+), 233 deletions(-)
 create mode 100644 .rubocop.yml
 create mode 100644 test/database_rails6.yml

diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 0000000..f816aea
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,63 @@
+AllCops:
+  TargetRubyVersion: 2.5
+  Exclude:
+    - ".git/**/*"
+    - "gemfiles/*"
+  NewCops: enable
+
+#
+# RuboCop built-in settings.
+#   For documentation on all settings see: https://docs.rubocop.org/en/stable
+#
+
+# Turn on auto-correction of equals alignment.
+Layout/EndAlignment:
+  AutoCorrect: true
+
+# Prevent accidental windows line endings
+Layout/EndOfLine:
+  EnforcedStyle: lf
+
+# Use a table layout for hashes
+Layout/HashAlignment:
+  EnforcedHashRocketStyle: table
+  EnforcedColonStyle: table
+
+# Match existing layout
+Layout/SpaceInsideHashLiteralBraces:
+  EnforcedStyle: no_space
+
+# Support long block lengths for tests
+Metrics/BlockLength:
+  Exclude:
+    - "test/**/*"
+
+# Initialization Vector abbreviation
+Naming/MethodParameterName:
+  AllowedNames: ['iv', '_', 'io', 'ap']
+
+# Does not allow Symbols to load
+Security/YAMLLoad:
+  AutoCorrect: false
+
+# Needed for testing DateTime
+Style/DateTime:
+  Exclude: ["test/**/*"]
+
+Style/Documentation:
+  Enabled: false
+
+# One line methods
+Style/EmptyMethod:
+  EnforcedStyle: expanded
+
+Style/NumericPredicate:
+  AutoCorrect: true
+
+# Since English may not be loaded, cannot force its use.
+Style/SpecialGlobalVars:
+  Enabled: false
+
+# Match Rails
+Style/StringLiterals:
+  EnforcedStyle: double_quotes
diff --git a/.travis.yml b/.travis.yml
index 1027726..596cbce 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,51 +3,27 @@ bundler_args: --without development
 
 matrix:
   include:
-    - name: "Rails 4.2 on Ruby 2.3.8"
-      rvm: 2.3.8
-      gemfile: gemfiles/rails_4.2.gemfile
-
-    - name: "Rails 5.0 on Ruby 2.4.7"
-      rvm: 2.4.7
-      gemfile: gemfiles/rails_5.0.gemfile
-    - name: "Rails 5.1 on Ruby 2.4.7"
-      rvm: 2.4.7
-      gemfile: gemfiles/rails_5.1.gemfile
-    - name: "Rails 5.2 on Ruby 2.4.7"
-      rvm: 2.4.7
-      gemfile: gemfiles/rails_5.2.gemfile
-
-    - name: "Rails 5.0 on Ruby 2.5.6"
-      rvm: 2.5.6
-      gemfile: gemfiles/rails_5.0.gemfile
-    - name: "Rails 5.1 on Ruby 2.5.6"
-      rvm: 2.5.6
-      gemfile: gemfiles/rails_5.1.gemfile
-    - name: "Rails 5.2 on Ruby 2.5.6"
-      rvm: 2.5.6
-      gemfile: gemfiles/rails_5.2.gemfile
-
-    - name: "Rails 5.2 on Ruby 2.6.3"
-      rvm: 2.6.3
-      gemfile: gemfiles/rails_5.2.gemfile
-
-    - name: "Rails 5.2 on JRuby 9.2.8.0"
-      rvm: jruby-9.2.8.0
-      gemfile: gemfiles/rails_5.2.gemfile
+    - name: "Rails 6.0 on Ruby 2.5.8"
+      rvm: 2.5.8
+      gemfile: gemfiles/rails_6.0.gemfile
+    - name: "Rails 6.0 on JRuby 9.2.13.0"
+      rvm: jruby-9.2.13.0
+      gemfile: gemfiles/rails_6.0.gemfile
+
+    - name: "Rails 6.1 on Ruby 2.6.6"
+      rvm: 2.6.6
+      gemfile: gemfiles/rails_6.1.gemfile
+    - name: "Rails 6.1 on Ruby 2.7.2"
+      rvm: 2.7.2
+      gemfile: gemfiles/rails_6.1.gemfile
+    - name: "Rails 6.1 on JRuby 9.2.13.0"
+      rvm: jruby-9.2.13.0
+      gemfile: gemfiles/rails_6.1.gemfile
 
   allow_failures:
-    - rvm: jruby-9.2.8.0
+    - rvm: jruby-9.2.13.0
 
 jdk:
   - openjdk10
 
-# Gitter integration
-notifications:
-  webhooks:
-    urls:
-      - https://webhooks.gitter.im/e/4d6749e48eb60321640e
-    on_success: change  # options: [always|never|change] default: always
-    on_failure: always  # options: [always|never|change] default: always
-    on_start: never     # options: [always|never|change] default: always
-
 sudo: false
diff --git a/Appraisals b/Appraisals
index 490a7d2..37d695c 100644
--- a/Appraisals
+++ b/Appraisals
@@ -1,16 +1,21 @@
-appraise 'rails_4.2' do
-  gem 'activerecord', '~> 4.2.0'
-  gem 'activerecord-jdbcsqlite3-adapter', '~> 1.0', platform: :jruby
+# frozen_string_literal: true
+
+appraise "rails_5.0" do
+  gem "activerecord", "~> 5.0"
+end
+
+appraise "rails_5.1" do
+  gem "activerecord", "~> 5.1.0"
 end
 
-appraise 'rails_5.0' do
-  gem 'activerecord', '~> 5.0'
+appraise "rails_5.2" do
+  gem "activerecord", "~> 5.2.3"
 end
 
-appraise 'rails_5.1' do
-  gem 'activerecord', '~> 5.1.0'
+appraise "rails_6.0" do
+  gem "activerecord", "~> 6.0.3"
 end
 
-appraise 'rails_5.2' do
-  gem 'activerecord', '~> 5.2.3'
+appraise "rails_6.1" do
+  gem "activerecord", "~> 6.1.0"
 end
diff --git a/Gemfile b/Gemfile
index 8f4ffdd..8751a8c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,15 +1,17 @@
-source 'https://rubygems.org'
+# frozen_string_literal: true
 
-gemspec
+source "https://rubygems.org"
 
-gem 'rake'
-gem 'minitest'
-gem 'awesome_print'
+gemspec
 
-gem 'sqlite3', '~> 1.3.0', platform: :ruby
-gem 'jdbc-sqlite3', platform: :jruby
-gem 'activerecord-jdbcsqlite3-adapter', platform: :jruby
-gem 'appraisal'
+gem "amazing_print"
+gem "minitest"
+gem "rake"
 
-gem 'activerecord', '~> 5.2.0'
+gem "activerecord-jdbcsqlite3-adapter", platform: :jruby
+gem "appraisal"
+gem "jdbc-sqlite3", platform: :jruby
+gem "sqlite3", platform: :ruby
 
+# gem "activerecord", "~> 5.2.0"
+gem "activerecord", "~> 6.0.3"
diff --git a/README.md b/README.md
index de1c1e2..7ff132d 100644
--- a/README.md
+++ b/README.md
@@ -59,13 +59,13 @@ Log file output:
 
 ### Example showing how reads within a transaction go to the primary
 
-```ruby
+~~~ruby
 Role.transaction do
   r = Role.where(name: 'manager').first
   r.description = 'Manager'
   r.save!
 end
-```
+~~~
 
 Log file output:
 
@@ -76,11 +76,11 @@ Log file output:
 
 Sometimes it is necessary to read from the primary:
 
-```ruby
+~~~ruby
 ActiveRecordReplica.read_from_primary do
   r = Role.where(name: 'manager').first
 end
-```
+~~~
 
 ## Usage Notes
 
@@ -88,21 +88,21 @@ end
 
 Delete all executes against the primary database since it is only a delete:
 
-```
+~~~
 D, [2012-11-06T19:47:29.125932 #89772] DEBUG -- :   SQL (1.0ms)  DELETE FROM "users"
-```
+~~~
 
 ### destroy_all
 
 First performs a read against the replica database and then deletes the corresponding
 data from the primary
 
-```
+~~~
 D, [2012-11-06T19:43:26.890674 #89002] DEBUG -- :   Replica: User Load (0.1ms)  SELECT "users".* FROM "users"
 D, [2012-11-06T19:43:26.890972 #89002] DEBUG -- :    (0.0ms)  begin transaction
 D, [2012-11-06T19:43:26.891667 #89002] DEBUG -- :   SQL (0.4ms)  DELETE FROM "users" WHERE "users"."id" = ?  [["id", 3]]
 D, [2012-11-06T19:43:26.892697 #89002] DEBUG -- :    (0.9ms)  commit transaction
-```
+~~~
 
 ## Transactions
 
@@ -114,16 +114,16 @@ inside a transaction:
 
 In file config/application.rb:
 
-```ruby
+~~~ruby
 # Read from replica even when in an active transaction
 config.active_record_replica.ignore_transactions = true
-```
+~~~
 
 It is important to identify any code in the application that depends on being
 able to read any changes already part of the transaction, but not yet committed
 and wrap those reads with `ActiveRecordReplica.read_from_primary`
 
-```ruby
+~~~ruby
 Inquiry.transaction do
   # Create a new inquiry
   Inquiry.create
@@ -133,9 +133,8 @@ Inquiry.transaction do
   ActiveRecordReplica.read_from_primary do
     count = Inquiry.count
   end
-
 end
-```
+~~~
 
 ## Note
 
@@ -168,17 +167,17 @@ When performing in-memory only model assignments Active Record will create a tra
 the transaction may never be used.
 
 Even though the transaction is unused it sends the following messages to the primary database:
-~~
+~~~sql
 SET autocommit=0
 commit
 SET autocommit=1
-~~
+~~~
 
 This will impact the primary database if sufficient calls are made, such as in batch workers.
 
 For Example:
 
-~~ruby
+~~~ruby
 class Parent < ActiveRecord::Base
   has_one :child, dependent: :destroy
 end
@@ -190,7 +189,7 @@ end
 # The following code will create an unused transaction against the primary, even when reads are going to replicas:
 parent = Parent.new
 parent.child = Child.new
-~~
+~~~
 
 If the `dependent: :destroy` is removed it no longer creates a transaction, but it also means dependents are not
 destroyed when a parent is destroyed.
@@ -198,135 +197,175 @@ destroyed when a parent is destroyed.
 For this scenario when we are 100% confident no writes are being performed the following can be performed to
 ignore any attempt Active Record makes at creating the transaction:
 
-~~ruby
+~~~ruby
 ActiveRecordReplica.skip_transactions do
   parent = Parent.new
   parent.child = Child.new
 end
-~~
+~~~
 
 To help identify any code within a block that is creating transactions, wrap the code with
 `ActiveRecordReplica.block_transactions` to make it raise an exception anytime a transaction is attempted:
 
-~~ruby
+~~~ruby
 ActiveRecordReplica.block_transactions do
   parent = Parent.new
   parent.child = Child.new
 end
-~~
+~~~
+
+## Rails 6 and above
 
-## Install
+Rails 6 natively supports multiple databases. It unfortunately only supports connection switching, so it cannot
+transparently redirect reads to a replica database the way ActiveRecordReplica does.
+
+### Installation
 
 Add to `Gemfile`
 
-```ruby
-gem 'active_record_replica'
-```
+~~~ruby
+gem "active_record_replica", "~>3.0"
+~~~
 
-Run bundler to install:
+### Configuration
 
-```
-bundle
-```
+Move the existing database config into a section under `primary` and add another section called `primary_reader`
+with `replica: true` to `database.yml`, for example:
+
+~~~yaml
+config: &config
+  database: production
+  username: username
+  password: password
+  encoding: utf8
+  adapter:  mysql
+  pool:     50
+
+production:
+  primary:
+    <<: *config
+    host: primary1
+  primary_reader:
+    <<: *config
+    host: replica1
+    replica: true
+~~~
+
+In order to tell Active Record about these entries, add the required entry to `ApplicationRecord`.
+For example:
+
+~~~ruby
+class ApplicationRecord < ActiveRecord::Base
+  self.abstract_class = true
+
+  connects_to database: {writing: :primary, reading: :primary_reader}
+end
+~~~
 
-Or, without Bundler:
+Rails recommends that all user models should inherit from ApplicationRecord, but if your models still inherit
+directly from `ActiveRecord::Base` then the following code could be used:
 
-```
-gem install active_record_replica
-```
+~~~ruby
+# Not recommended
+class ActiveRecord::Base
+  connects_to database: {writing: :primary, reading: :primary_reader}
+end
+~~~
 
-## Configuration
+## Rails 4 & 5
+
+### Installation
+
+Add to `Gemfile`
+
+~~~ruby
+gem "active_record_replica", "~>2.0"
+~~~
+
+### Configuration
 
 To enable replica reads for any environment just add a _replica:_ entry to database.yml
 along with all the usual ActiveRecord database configuration options.
 
 For Example:
 
-```yaml
-production:
+~~~yaml
+config: &config
   database: production
   username: username
   password: password
   encoding: utf8
   adapter:  mysql
-  host:     primary1
   pool:     50
+
+production:
+  <<: *config
+  host:     primary1
   replica:
-    database: production
-    username: username
-    password: password
-    encoding: utf8
-    adapter:  mysql
-    host:     replica1
-    pool:     50
-```
+    <<: *config
+    host:   replica1
+~~~
 
 Sometimes it is useful to turn on replica reads per host, for example to activate
 replica reads only on the linux host 'batch':
 
-```yaml
-production:
+~~~yaml
+config: &config
   database: production
   username: username
   password: password
   encoding: utf8
   adapter:  mysql
-  host:     primary1
   pool:     50
+
+production:
+  <<: *config
+  host:     primary1
 <% if `hostname`.strip == 'batch' %>
   replica:
-    database: production
-    username: username
-    password: password
-    encoding: utf8
-    adapter:  mysql
+    <<: *config
     host:     replica1
-    pool:     50
 <% end %>
-```
+~~~
 
 If there are multiple replicas, it is possible to randomly select a replica on startup
 to balance the load across the replicas:
 
-```yaml
-production:
+~~~yaml
+config: &config
   database: production
   username: username
   password: password
   encoding: utf8
   adapter:  mysql
-  host:     primary1
   pool:     50
+
+production:
+  <<: *config
+  host:     primary1
   replica:
-    database: production
-    username: username
-    password: password
-    encoding: utf8
-    adapter:  mysql
-    host:     <%= %w(replica1 replica2 replica3).sample %>
-    pool:     50
-```
+    <<: *config
+    host: <%= %w(replica1 replica2 replica3).sample %>
+~~~
 
 Replicas can also be assigned to specific hosts by using the hostname:
 
-```yaml
-production:
+~~~yaml
+config: &config
   database: production
   username: username
   password: password
   encoding: utf8
   adapter:  mysql
-  host:     primary1
   pool:     50
+
+production:
+  <<: *config
+  host:     primary1
   replica:
-    database: production
-    username: username
-    password: password
-    encoding: utf8
-    adapter:  mysql
-    host:     <%= `hostname`.strip == 'app1' ? 'replica1' : 'replica2' %>
-    pool:     50
-```
+    <<: *config
+    host:   <%= `hostname`.strip == 'app1' ? 'replica1' : 'replica2' %>
+~~~
 
 ## Set primary as default for Read
 
@@ -334,17 +373,17 @@ The default behavior can also set to read/write operations against primary datab
 
 Create an initializer file config/initializer/active_record_replica.rb to force read from primary:
 
-```yaml
-    ActiveRecordReplica.read_from_primary!
-```
+~~~ruby
+ActiveRecordReplica.read_from_primary!
+~~~
 
 Then use this method and supply block to read from the replica database:
 
-```yaml
+~~~ruby
 ActiveRecordReplica.read_from_replica do
-   User.count
+  User.count
 end
-```
+~~~
 
 ## Dependencies
 
@@ -360,16 +399,16 @@ This project uses [Semantic Versioning](http://semver.org/).
 
 2. Checkout your forked repository:
 
-    ```bash
-    git clone https://github.com/your_github_username/active_record_replica.git
-    cd active_record_replica
-    ```
+~~~shell
+git clone https://github.com/your_github_username/active_record_replica.git
+cd active_record_replica
+~~~
 
 3. Create branch for your contribution:
 
-    ```bash
-    git co -b your_new_branch_name
-    ```
+~~~shell
+git co -b your_new_branch_name
+~~~
 
 4. Make code changes.
 
@@ -377,9 +416,9 @@ This project uses [Semantic Versioning](http://semver.org/).
 
 6. Push to your fork origin.
 
-    ```bash
-    git push origin
-    ```
+~~~shell
+git push origin
+~~~
 
 7. Submit PR from the branch on your fork in Github.
 
diff --git a/Rakefile b/Rakefile
index 71637e0..79c9c98 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,15 +1,17 @@
+# frozen_string_literal: true
+
 # Setup bundler to avoid having to run bundle exec all the time.
-require 'rubygems'
-require 'bundler/setup'
+require "rubygems"
+require "bundler/setup"
 
-require 'rake/testtask'
-require_relative 'lib/active_record_replica/version'
+require "rake/testtask"
+require_relative "lib/active_record_replica/version"
 
 task :gem do
   system "gem build active_record_replica.gemspec"
 end
 
-task :publish => :gem do
+task publish: :gem do
   system "git tag -a v#{ActiveRecordReplica::VERSION} -m 'Tagging #{ActiveRecordReplica::VERSION}'"
   system "git push --tags"
   system "gem push active_record_replica-#{ActiveRecordReplica::VERSION}.gem"
@@ -17,14 +19,14 @@ task :publish => :gem do
 end
 
 Rake::TestTask.new(:test) do |t|
-  t.pattern = 'test/**/*_test.rb'
+  t.pattern = "test/**/*_test.rb"
   t.verbose = true
   t.warning = false
 end
 
 # By default run tests against all appraisals
 if !ENV["APPRAISAL_INITIALIZED"] && !ENV["TRAVIS"]
-  require 'appraisal'
+  require "appraisal"
   task default: :appraisal
 else
   task default: :test
diff --git a/active_record_replica.gemspec b/active_record_replica.gemspec
index 6b231b9..58997c6 100644
--- a/active_record_replica.gemspec
+++ b/active_record_replica.gemspec
@@ -1,20 +1,22 @@
-$:.push File.expand_path('../lib', __FILE__)
+# frozen_string_literal: true
+
+$LOAD_PATH.push File.expand_path("lib", __dir__)
 
 # Maintain your gem's version:
-require 'active_record_replica/version'
+require "active_record_replica/version"
 
 # Describe your gem and declare its dependencies:
 Gem::Specification.new do |spec|
-  spec.name                  = 'active_record_replica'
+  spec.name                  = "active_record_replica"
   spec.version               = ActiveRecordReplica::VERSION
   spec.platform              = Gem::Platform::RUBY
-  spec.authors               = ['Reid Morrison']
-  spec.email                 = ['reidmo@gmail.com']
-  spec.homepage              = 'https://github.com/rocketjob/active_record_replica'
-  spec.summary               = 'Redirect ActiveRecord (Rails) reads to replica databases while ensuring all writes go to the primary database.'
-  spec.files                 = Dir['lib/**/*', 'LICENSE.txt', 'Rakefile', 'README.md']
-  spec.test_files            = Dir['test/**/*']
-  spec.license               = 'Apache-2.0'
-  spec.required_ruby_version = '>= 2.0'
-  spec.add_dependency 'activerecord', '>= 3.0', '< 6.0.0'
+  spec.authors               = ["Reid Morrison"]
+  spec.email                 = ["reidmo@gmail.com"]
+  spec.homepage              = "https://github.com/rocketjob/active_record_replica"
+  spec.summary               = "Redirect ActiveRecord (Rails) reads to replica databases while ensuring all writes go to the primary database."
+  spec.files                 = Dir["lib/**/*", "LICENSE.txt", "Rakefile", "README.md"]
+  spec.test_files            = Dir["test/**/*"]
+  spec.license               = "Apache-2.0"
+  spec.required_ruby_version = ">= 2.5"
+  spec.add_dependency "activerecord", ">= 4.2"
 end
diff --git a/lib/active_record_replica.rb b/lib/active_record_replica.rb
index 33df46d..6d14b51 100644
--- a/lib/active_record_replica.rb
+++ b/lib/active_record_replica.rb
@@ -1,11 +1,11 @@
-require 'active_record'
-require 'active_record/base'
-require 'active_record_replica/version'
-require 'active_record_replica/errors'
-require 'active_record_replica/replica'
-require 'active_record_replica/active_record_replica'
-require 'active_record_replica/extensions'
+# frozen_string_literal: true
 
-if defined?(Rails)
-  require 'active_record_replica/railtie'
-end
+require "active_record"
+require "active_record/base"
+require "active_record_replica/errors"
+require "active_record_replica/replica" unless ActiveRecord::VERSION::MAJOR >= 6
+require "active_record_replica/version"
+require "active_record_replica/active_record_replica"
+require "active_record_replica/extensions"
+
+require "active_record_replica/railtie" if defined?(Rails)
diff --git a/lib/active_record_replica/active_record_replica.rb b/lib/active_record_replica/active_record_replica.rb
index 00a6f91..9282a5a 100644
--- a/lib/active_record_replica/active_record_replica.rb
+++ b/lib/active_record_replica/active_record_replica.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 #
 # ActiveRecord read from a replica
 #
@@ -11,41 +13,53 @@ module ActiveRecordReplica
   #   environment:
   #     In a non-Rails environment, supply the environment such as
   #     'development', 'production'
-  def self.install!(adapter_class = nil, environment = nil)
-    replica_config = ActiveRecord::Base.configurations[environment || Rails.env]["replica"]
+  def self.install!(base: ActiveRecord::Base, adapter_class: nil, environment: nil)
+    replica_config = base.configurations[environment || Rails.env]["replica"]
     unless replica_config
-      ActiveRecord::Base.logger.info("ActiveRecordReplica not installed since no replica database defined")
-      return
+      base.logger.info("ActiveRecordReplica not installed since no replica database defined")
+      return false
     end
 
     # When the DBMS is not available, an exception (e.g. PG::ConnectionBad) is raised
-    active_db_connection = ActiveRecord::Base.connection.active? rescue false
+    active_db_connection = begin
+      ActiveRecord::Base.connection.active?
+    rescue StandardError
+      false
+    end
+
     unless active_db_connection
-      ActiveRecord::Base.logger.info("ActiveRecord not connected so not installing ActiveRecordReplica")
+      base.logger.info("ActiveRecord not connected so not installing ActiveRecordReplica")
       return
     end
 
     version = ActiveRecordReplica::VERSION
-    ActiveRecord::Base.logger.info("ActiveRecordReplica.install! v#{version} Establishing connection to replica database")
-    Replica.establish_connection(replica_config)
+    if ActiveRecord::VERSION::MAJOR >= 6
+      base.logger.info("ActiveRecordReplica.install! v#{version} redirecting reads to role: :reading")
+    else
+      base.logger.info("ActiveRecordReplica.install! v#{version} Establishing connection to replica database")
+      Replica.establish_connection(replica_config)
+    end
 
     # Inject a new #select method into the ActiveRecord Database adapter
-    base = adapter_class || ActiveRecord::Base.connection.class
-    base.include(Extensions)
+    adapter_class ||= base.connection.class
+    adapter_class.include(Extensions)
+    true
   end
 
-  # Force reads for the supplied block to read from the primary database
-  # Only applies to calls made within the current thread
+  # Force reads for the supplied block to read from the primary database.
+  # Only applies to calls made within the current thread.
+  #
+  # Note:
+  #   * This block overrides any value set with read_from_replica!
   def self.read_from_primary(&block)
     thread_variable_yield(:active_record_replica, :primary, &block)
   end
 
+  # Force reads for the supplied block to read from the replica database.
+  # Only applies to calls made within the current thread.
   #
-  # The default behavior can also set to read/write operations against primary
-  # Create an initializer file config/initializer/active_record_replica.rb
-  # and set ActiveRecordReplica.read_from_primary! to force read from primary.
-  # Then use this method and supply block to read from the replica database
-  # Only applies to calls made within the current thread
+  # Note:
+  #   * This block overrides any value set with read_from_primary!
   def self.read_from_replica(&block)
     thread_variable_yield(:active_record_replica, :replica, &block)
   end
@@ -86,11 +100,15 @@ def self.read_from_replica?
   # The default behavior can be set to read/write operations against primary.
   # Create an initializer file config/initializer/active_record_replica.rb
   # and set ActiveRecordReplica.read_from_primary! to force read from primary.
+  #
+  # Blocks of code can override this setting by calling .read_from_replica.
   def self.read_from_primary!
     @read_from_replica = false
   end
 
   # Force all subsequent reads in this process to read from the replica database.
+  #
+  # Blocks of code can override this setting by calling .read_from_primary.
   def self.read_from_replica!
     @read_from_replica = true
   end
@@ -115,8 +133,6 @@ def self.ignore_transactions=(ignore_transactions)
     @ignore_transactions = ignore_transactions
   end
 
-  private
-
   def self.thread_variable_equals(key, value)
     Thread.current.thread_variable_get(key) == value
   end
diff --git a/lib/active_record_replica/extensions.rb b/lib/active_record_replica/extensions.rb
index 963dd21..98605e9 100644
--- a/lib/active_record_replica/extensions.rb
+++ b/lib/active_record_replica/extensions.rb
@@ -1,65 +1,83 @@
-require 'active_support/concern'
+# frozen_string_literal: true
+
+require "active_support/concern"
 module ActiveRecordReplica
   module Extensions
     extend ActiveSupport::Concern
 
-    [:select, :select_all, :select_one, :select_rows, :select_value, :select_values].each do |select_method|
-      class_eval <<-RUBY, __FILE__, __LINE__ + 1
+    %i[select select_all select_one select_rows select_value select_values].each do |select_method|
+      class_eval <<~RUBY, __FILE__, __LINE__ + 1
         def #{select_method}(sql, name = nil, *args)
           return super if active_record_replica_read_from_primary?
-  
-          ActiveRecordReplica.read_from_primary do
-            reader_connection.#{select_method}(sql, "Replica: \#{name || 'SQL'}", *args)
-          end
+
+          active_record_replica_select(:#{select_method}, sql, name, *args)
         end
       RUBY
     end
 
-    def reader_connection
-      Replica.connection
+    if ActiveRecord::VERSION::MAJOR >= 6
+      def active_record_replica_select(select_method, sql, name = nil, *args)
+        ActiveRecordReplica.read_from_primary do
+          # if current_role == ActiveRecord::Base.reading_role
+          #   connection.public_send(select_method, sql, "Replica: \#{name || 'SQL'}", *args)
+          # else
+            ActiveRecord::Base.connected_to(role: ActiveRecord::Base.reading_role) do
+              connection.public_send(select_method, sql, "Replica: \#{name || 'SQL'}", *args)
+            end
+          # end
+        end
+      end
+    else
+      def active_record_replica_select(select_method, sql, name = nil, *args)
+        ActiveRecordReplica.read_from_primary do
+          reader_connection.public_send(select_method, sql, "Replica: \#{name || 'SQL'}", *args)
+        end
+      end
+
+      def reader_connection
+        Replica.connection
+      end
     end
 
     def begin_db_transaction
       return if ActiveRecordReplica.skip_transactions?
       return super unless ActiveRecordReplica.block_transactions?
 
-      raise(TransactionAttempted, 'Attempting to begin a transaction during a read-only database connection.')
+      raise(TransactionAttempted, "Attempting to begin a transaction during a read-only database connection.")
     end
 
     def commit_db_transaction
       return if ActiveRecordReplica.skip_transactions?
       return super unless ActiveRecordReplica.block_transactions?
 
-      raise(TransactionAttempted, 'Attempting to commit a transaction during a read-only database connection.')
+      raise(TransactionAttempted, "Attempting to commit a transaction during a read-only database connection.")
     end
 
     def create_savepoint(name = current_savepoint_name(true))
       return if ActiveRecordReplica.skip_transactions?
       return super unless ActiveRecordReplica.block_transactions?
 
-      raise(TransactionAttempted, 'Attempting to create a savepoint during a read-only database connection.')
+      raise(TransactionAttempted, "Attempting to create a savepoint during a read-only database connection.")
     end
 
     def rollback_to_savepoint(name = current_savepoint_name(true))
       return if ActiveRecordReplica.skip_transactions?
       return super unless ActiveRecordReplica.block_transactions?
 
-      raise(TransactionAttempted, 'Attempting to rollback a savepoint during a read-only database connection.')
+      raise(TransactionAttempted, "Attempting to rollback a savepoint during a read-only database connection.")
     end
 
     def release_savepoint(name = current_savepoint_name(true))
       return if ActiveRecordReplica.skip_transactions?
       return super unless ActiveRecordReplica.block_transactions?
 
-      raise(TransactionAttempted, 'Attempting to release a savepoint during a read-only database connection.')
+      raise(TransactionAttempted, "Attempting to release a savepoint during a read-only database connection.")
     end
 
     # Returns whether to read from the primary database
     def active_record_replica_read_from_primary?
-      # Read from primary when forced by thread variable, or
-      # in a transaction and not ignoring transactions
       ActiveRecordReplica.read_from_primary? ||
-        (open_transactions > 0) && !ActiveRecordReplica.ignore_transactions?
+        open_transactions.positive? && !ActiveRecordReplica.ignore_transactions?
     end
   end
 end
diff --git a/lib/active_record_replica/replica.rb b/lib/active_record_replica/replica.rb
index 1c0266f..3f4ec19 100644
--- a/lib/active_record_replica/replica.rb
+++ b/lib/active_record_replica/replica.rb
@@ -1,5 +1,7 @@
 module ActiveRecordReplica
   # Class to hold replica connection pool
+  #
+  # Note: Not used with Rails 6 and above
   class Replica < ActiveRecord::Base
     # Prevent Rails from trying to create an instance of this model
     self.abstract_class = true
diff --git a/test/database_rails6.yml b/test/database_rails6.yml
new file mode 100644
index 0000000..bbe8455
--- /dev/null
+++ b/test/database_rails6.yml
@@ -0,0 +1,23 @@
+config: &config
+  adapter:  sqlite3
+  pool:     5
+  timeout:  5000
+
+# Make the replica a separate database that is not replicated to ensure reads
+# and writes go to the appropriate databases
+test:
+  primary:
+    <<: *config
+    database: test/db1_primary.sqlite3
+  primary_reader:
+    <<: *config
+    database: test/db1_replica.sqlite3
+    replica: true
+
+  consumers:
+    <<: *config
+    database: test/db2_primary.sqlite3
+  consumers_reader:
+    <<: *config
+    database: test/db2_replica.sqlite3
+    replica: true
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 54c7502..7cac744 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,24 +1,28 @@
-ENV['RAILS_ENV'] = 'test'
+# frozen_string_literal: true
 
-require 'active_record'
-require 'minitest/autorun'
-require 'active_record_replica'
-require 'awesome_print'
-require 'logger'
-require 'erb'
+ENV["RAILS_ENV"] = "test"
 
-l                                 = Logger.new('test.log')
+require "active_record"
+require "minitest/autorun"
+require "active_record_replica"
+require "amazing_print"
+require "logger"
+require "erb"
+
+config_file_name = ActiveRecord::VERSION::MAJOR >= 6 ? "test/database_rails6.yml" : "test/database.yml"
+
+l                                 = Logger.new("test.log")
 l.level                           = ::Logger::DEBUG
 ActiveRecord::Base.logger         = l
-ActiveRecord::Base.configurations = YAML::load(ERB.new(IO.read('test/database.yml')).result)
+ActiveRecord::Base.configurations = YAML.load(ERB.new(IO.read(config_file_name)).result)
 
 # Define Schema in second database (replica)
 # Note: This is not be required when the primary database is being replicated to the replica db
-ActiveRecord::Base.establish_connection(ActiveRecord::Base.configurations['test']['replica'])
+ActiveRecord::Base.establish_connection(ActiveRecord::Base.configurations["test"]["replica"])
 
 # Create table users in database active_record_replica_test
-ActiveRecord::Schema.define :version => 0 do
-  create_table :users, :force => true do |t|
+ActiveRecord::Schema.define version: 0 do
+  create_table :users, force: true do |t|
     t.string :name
     t.string :address
   end
@@ -28,8 +32,8 @@
 ActiveRecord::Base.establish_connection(:test)
 
 # Create table users in database active_record_replica_test
-ActiveRecord::Schema.define :version => 0 do
-  create_table :users, :force => true do |t|
+ActiveRecord::Schema.define version: 0 do
+  create_table :users, force: true do |t|
     t.string :name
     t.string :address
   end
@@ -41,4 +45,4 @@ class User < ActiveRecord::Base
 
 # Install ActiveRecord replica. Done automatically by railtie in a Rails environment
 # Also tell it to use the test environment since Rails.env is not available
-ActiveRecordReplica.install!(nil, 'test')
+ActiveRecordReplica.install!(environment: "test")

From 8af418ee98e74a9099a3c86a8abb598ced8b4e1d Mon Sep 17 00:00:00 2001
From: Reid Morrison <reidmo@gmail.com>
Date: Mon, 4 Jan 2021 16:30:06 -0500
Subject: [PATCH 2/7] Single database support

---
 .travis.yml                                   | 38 +++++++++++++--
 Appraisals                                    |  5 ++
 README.md                                     |  8 ++--
 active_record_replica.gemspec                 |  5 +-
 gemfiles/rails_4.2.gemfile                    |  8 ++--
 gemfiles/rails_5.0.gemfile                    |  8 ++--
 gemfiles/rails_5.1.gemfile                    |  8 ++--
 gemfiles/rails_5.2.gemfile                    |  8 ++--
 gemfiles/rails_6.0.gemfile                    | 14 ++++++
 gemfiles/rails_6.1.gemfile                    | 14 ++++++
 .../active_record_replica.rb                  | 10 ++--
 lib/active_record_replica/extensions.rb       | 10 ++--
 test/database_rails6.yml                      |  4 +-
 test/test_helper.rb                           | 46 ++++++++++++-------
 14 files changed, 132 insertions(+), 54 deletions(-)
 create mode 100644 gemfiles/rails_6.0.gemfile
 create mode 100644 gemfiles/rails_6.1.gemfile

diff --git a/.travis.yml b/.travis.yml
index 596cbce..f2bb3b4 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,11 +3,39 @@ bundler_args: --without development
 
 matrix:
   include:
+    - name: "Rails 4.2 on Ruby 2.3.8"
+      rvm: 2.3.8
+      gemfile: gemfiles/rails_4.2.gemfile
+
+    - name: "Rails 5.0 on Ruby 2.4.7"
+      rvm: 2.4.7
+      gemfile: gemfiles/rails_5.0.gemfile
+    - name: "Rails 5.1 on Ruby 2.4.7"
+      rvm: 2.4.7
+      gemfile: gemfiles/rails_5.1.gemfile
+    - name: "Rails 5.2 on Ruby 2.4.7"
+      rvm: 2.4.7
+      gemfile: gemfiles/rails_5.2.gemfile
+
+    - name: "Rails 5.0 on Ruby 2.5.8"
+      rvm: 2.5.8
+      gemfile: gemfiles/rails_5.0.gemfile
+    - name: "Rails 5.1 on Ruby 2.5.8"
+      rvm: 2.5.8
+      gemfile: gemfiles/rails_5.1.gemfile
+    - name: "Rails 5.2 on Ruby 2.5.8"
+      rvm: 2.5.8
+      gemfile: gemfiles/rails_5.2.gemfile
+
+    - name: "Rails 5.2 on Ruby 2.6.6"
+      rvm: 2.6.6
+      gemfile: gemfiles/rails_5.2.gemfile
+
     - name: "Rails 6.0 on Ruby 2.5.8"
       rvm: 2.5.8
       gemfile: gemfiles/rails_6.0.gemfile
-    - name: "Rails 6.0 on JRuby 9.2.13.0"
-      rvm: jruby-9.2.13.0
+    - name: "Rails 6.0 on JRuby 9.2.14.0"
+      rvm: jruby-9.2.14.0
       gemfile: gemfiles/rails_6.0.gemfile
 
     - name: "Rails 6.1 on Ruby 2.6.6"
@@ -16,12 +44,12 @@ matrix:
     - name: "Rails 6.1 on Ruby 2.7.2"
       rvm: 2.7.2
       gemfile: gemfiles/rails_6.1.gemfile
-    - name: "Rails 6.1 on JRuby 9.2.13.0"
-      rvm: jruby-9.2.13.0
+    - name: "Rails 6.1 on JRuby 9.2.14.0"
+      rvm: jruby-9.2.14.0
       gemfile: gemfiles/rails_6.1.gemfile
 
   allow_failures:
-    - rvm: jruby-9.2.13.0
+    - rvm: jruby-9.2.14.0
 
 jdk:
   - openjdk10
diff --git a/Appraisals b/Appraisals
index 37d695c..8a7bca0 100644
--- a/Appraisals
+++ b/Appraisals
@@ -1,5 +1,10 @@
 # frozen_string_literal: true
 
+appraise "rails_4.2" do
+  gem "activerecord", "~> 4.2.0"
+  gem "activerecord-jdbcsqlite3-adapter", "~> 1.0", platform: :jruby
+end
+
 appraise "rails_5.0" do
   gem "activerecord", "~> 5.0"
 end
diff --git a/README.md b/README.md
index 7ff132d..db25b61 100644
--- a/README.md
+++ b/README.md
@@ -106,7 +106,7 @@ D, [2012-11-06T19:43:26.892697 #89002] DEBUG -- :    (0.9ms)  commit transaction
 
 ## Transactions
 
-By default ActiveRecordReplica detects when a call is inside a transaction and will
+By default Active Record Replica detects when a call is inside a transaction and will
 send all reads to the _primary_ when a transaction is active.
 
 It is now possible to send reads to database replicas and ignore whether currently
@@ -217,14 +217,14 @@ end
 ## Rails 6 and above
 
 Rails 6 natively supports multiple databases. It unfortunately only supports connection switching, so it cannot
-transparently redirect reads to a replica database the way ActiveRecordReplica does.
+transparently redirect reads to a replica database the way Active Record Replica does.
 
 ### Installation
 
 Add to `Gemfile`
 
 ~~~ruby
-gem "active_record_replica", "~>3.0"
+gem "active_record_replica"
 ~~~
 
 ### Configuration
@@ -279,7 +279,7 @@ end
 Add to `Gemfile`
 
 ~~~ruby
-gem "active_record_replica", "~>2.0"
+gem "active_record_replica"
 ~~~
 
 ### Configuration
diff --git a/active_record_replica.gemspec b/active_record_replica.gemspec
index 58997c6..4ed0f1b 100644
--- a/active_record_replica.gemspec
+++ b/active_record_replica.gemspec
@@ -10,9 +10,8 @@ Gem::Specification.new do |spec|
   spec.name                  = "active_record_replica"
   spec.version               = ActiveRecordReplica::VERSION
   spec.platform              = Gem::Platform::RUBY
-  spec.authors               = ["Reid Morrison"]
-  spec.email                 = ["reidmo@gmail.com"]
-  spec.homepage              = "https://github.com/rocketjob/active_record_replica"
+  spec.authors               = ["Reid Morrison", "James Brady"]
+  spec.homepage              = "https://github.com/teespring/active_record_replica"
   spec.summary               = "Redirect ActiveRecord (Rails) reads to replica databases while ensuring all writes go to the primary database."
   spec.files                 = Dir["lib/**/*", "LICENSE.txt", "Rakefile", "README.md"]
   spec.test_files            = Dir["test/**/*"]
diff --git a/gemfiles/rails_4.2.gemfile b/gemfiles/rails_4.2.gemfile
index a05c02d..830ac95 100644
--- a/gemfiles/rails_4.2.gemfile
+++ b/gemfiles/rails_4.2.gemfile
@@ -2,13 +2,13 @@
 
 source "https://rubygems.org"
 
-gem "rake"
+gem "amazing_print"
 gem "minitest"
-gem "awesome_print"
-gem "sqlite3", "~> 1.3.0", platform: :ruby
-gem "jdbc-sqlite3", platform: :jruby
+gem "rake"
 gem "activerecord-jdbcsqlite3-adapter", "~> 1.0", platform: :jruby
 gem "appraisal"
+gem "jdbc-sqlite3", platform: :jruby
+gem "sqlite3", platform: :ruby
 gem "activerecord", "~> 4.2.0"
 
 gemspec path: "../"
diff --git a/gemfiles/rails_5.0.gemfile b/gemfiles/rails_5.0.gemfile
index 7a02cf7..59ea279 100644
--- a/gemfiles/rails_5.0.gemfile
+++ b/gemfiles/rails_5.0.gemfile
@@ -2,13 +2,13 @@
 
 source "https://rubygems.org"
 
-gem "rake"
+gem "amazing_print"
 gem "minitest"
-gem "awesome_print"
-gem "sqlite3", "~> 1.3.0", platform: :ruby
-gem "jdbc-sqlite3", platform: :jruby
+gem "rake"
 gem "activerecord-jdbcsqlite3-adapter", platform: :jruby
 gem "appraisal"
+gem "jdbc-sqlite3", platform: :jruby
+gem "sqlite3", platform: :ruby
 gem "activerecord", "~> 5.0"
 
 gemspec path: "../"
diff --git a/gemfiles/rails_5.1.gemfile b/gemfiles/rails_5.1.gemfile
index d3ae36a..3170b86 100644
--- a/gemfiles/rails_5.1.gemfile
+++ b/gemfiles/rails_5.1.gemfile
@@ -2,13 +2,13 @@
 
 source "https://rubygems.org"
 
-gem "rake"
+gem "amazing_print"
 gem "minitest"
-gem "awesome_print"
-gem "sqlite3", "~> 1.3.0", platform: :ruby
-gem "jdbc-sqlite3", platform: :jruby
+gem "rake"
 gem "activerecord-jdbcsqlite3-adapter", platform: :jruby
 gem "appraisal"
+gem "jdbc-sqlite3", platform: :jruby
+gem "sqlite3", platform: :ruby
 gem "activerecord", "~> 5.1.0"
 
 gemspec path: "../"
diff --git a/gemfiles/rails_5.2.gemfile b/gemfiles/rails_5.2.gemfile
index c84416b..a0c07ac 100644
--- a/gemfiles/rails_5.2.gemfile
+++ b/gemfiles/rails_5.2.gemfile
@@ -2,13 +2,13 @@
 
 source "https://rubygems.org"
 
-gem "rake"
+gem "amazing_print"
 gem "minitest"
-gem "awesome_print"
-gem "sqlite3", "~> 1.3.0", platform: :ruby
-gem "jdbc-sqlite3", platform: :jruby
+gem "rake"
 gem "activerecord-jdbcsqlite3-adapter", platform: :jruby
 gem "appraisal"
+gem "jdbc-sqlite3", platform: :jruby
+gem "sqlite3", platform: :ruby
 gem "activerecord", "~> 5.2.3"
 
 gemspec path: "../"
diff --git a/gemfiles/rails_6.0.gemfile b/gemfiles/rails_6.0.gemfile
new file mode 100644
index 0000000..44cd273
--- /dev/null
+++ b/gemfiles/rails_6.0.gemfile
@@ -0,0 +1,14 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "amazing_print"
+gem "minitest"
+gem "rake"
+gem "activerecord-jdbcsqlite3-adapter", platform: :jruby
+gem "appraisal"
+gem "jdbc-sqlite3", platform: :jruby
+gem "sqlite3", platform: :ruby
+gem "activerecord", "~> 6.0.3"
+
+gemspec path: "../"
diff --git a/gemfiles/rails_6.1.gemfile b/gemfiles/rails_6.1.gemfile
new file mode 100644
index 0000000..a404288
--- /dev/null
+++ b/gemfiles/rails_6.1.gemfile
@@ -0,0 +1,14 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "amazing_print"
+gem "minitest"
+gem "rake"
+gem "activerecord-jdbcsqlite3-adapter", platform: :jruby
+gem "appraisal"
+gem "jdbc-sqlite3", platform: :jruby
+gem "sqlite3", platform: :ruby
+gem "activerecord", "~> 6.1.0"
+
+gemspec path: "../"
diff --git a/lib/active_record_replica/active_record_replica.rb b/lib/active_record_replica/active_record_replica.rb
index 9282a5a..f64a069 100644
--- a/lib/active_record_replica/active_record_replica.rb
+++ b/lib/active_record_replica/active_record_replica.rb
@@ -14,10 +14,12 @@ module ActiveRecordReplica
   #     In a non-Rails environment, supply the environment such as
   #     'development', 'production'
   def self.install!(base: ActiveRecord::Base, adapter_class: nil, environment: nil)
-    replica_config = base.configurations[environment || Rails.env]["replica"]
-    unless replica_config
-      base.logger.info("ActiveRecordReplica not installed since no replica database defined")
-      return false
+    if ActiveRecord::VERSION::MAJOR < 6
+      replica_config = base.configurations[environment || Rails.env]["replica"]
+      unless replica_config
+        base.logger.info("ActiveRecordReplica not installed since no replica database defined")
+        return false
+      end
     end
 
     # When the DBMS is not available, an exception (e.g. PG::ConnectionBad) is raised
diff --git a/lib/active_record_replica/extensions.rb b/lib/active_record_replica/extensions.rb
index 98605e9..472b657 100644
--- a/lib/active_record_replica/extensions.rb
+++ b/lib/active_record_replica/extensions.rb
@@ -18,13 +18,13 @@ def #{select_method}(sql, name = nil, *args)
     if ActiveRecord::VERSION::MAJOR >= 6
       def active_record_replica_select(select_method, sql, name = nil, *args)
         ActiveRecordReplica.read_from_primary do
-          # if current_role == ActiveRecord::Base.reading_role
-          #   connection.public_send(select_method, sql, "Replica: \#{name || 'SQL'}", *args)
-          # else
+          if ActiveRecord::Base.current_role == ActiveRecord::Base.reading_role
+            public_send(select_method, sql, "Replica: #{name || 'SQL'}", *args)
+          else
             ActiveRecord::Base.connected_to(role: ActiveRecord::Base.reading_role) do
-              connection.public_send(select_method, sql, "Replica: \#{name || 'SQL'}", *args)
+              ActiveRecord::Base.connection.public_send(select_method, sql, "Replica: #{name || 'SQL'}", *args)
             end
-          # end
+          end
         end
       end
     else
diff --git a/test/database_rails6.yml b/test/database_rails6.yml
index bbe8455..95469a0 100644
--- a/test/database_rails6.yml
+++ b/test/database_rails6.yml
@@ -12,7 +12,9 @@ test:
   primary_reader:
     <<: *config
     database: test/db1_replica.sqlite3
-    replica: true
+    # In tests it writes the schema to the "replicated" database.
+    # Should set to true in production.
+    # replica: true
 
   consumers:
     <<: *config
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 7cac744..6eb33dd 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -16,31 +16,45 @@
 ActiveRecord::Base.logger         = l
 ActiveRecord::Base.configurations = YAML.load(ERB.new(IO.read(config_file_name)).result)
 
-# Define Schema in second database (replica)
-# Note: This is not be required when the primary database is being replicated to the replica db
-ActiveRecord::Base.establish_connection(ActiveRecord::Base.configurations["test"]["replica"])
+class ApplicationRecord < ActiveRecord::Base
+  self.abstract_class = true
 
-# Create table users in database active_record_replica_test
-ActiveRecord::Schema.define version: 0 do
-  create_table :users, force: true do |t|
-    t.string :name
-    t.string :address
+  if ActiveRecord::VERSION::MAJOR >= 6
+    connects_to database: { writing: :primary, reading: :primary_reader }
   end
 end
 
-# Define Schema in primary database
-ActiveRecord::Base.establish_connection(:test)
+# Active Record based model
+class User < ApplicationRecord
+end
 
 # Create table users in database active_record_replica_test
-ActiveRecord::Schema.define version: 0 do
-  create_table :users, force: true do |t|
-    t.string :name
-    t.string :address
+def create_schema
+  ActiveRecord::Schema.define version: 0 do
+    create_table :users, force: true do |t|
+      t.string :name
+      t.string :address
+    end
   end
 end
 
-# AR Model
-class User < ActiveRecord::Base
+# Define Schema in both databases.
+# Note: This is for testing purposes only and not needed by a Rails app.
+if ActiveRecord::VERSION::MAJOR >= 6
+  ApplicationRecord.connected_to(database: :primary_reader) do
+    create_schema
+  end
+  ApplicationRecord.connected_to(database: :primary) do
+    create_schema
+  end
+  ApplicationRecord.establish_connection(:test)
+else
+  ApplicationRecord.establish_connection(ActiveRecord::Base.configurations["test"]["replica"])
+  create_schema
+
+  # Define Schema in primary database
+  ApplicationRecord.establish_connection(:test)
+  create_schema
 end
 
 # Install ActiveRecord replica. Done automatically by railtie in a Rails environment

From 6652639c4c6c6040df830cdd94570cbe92359a71 Mon Sep 17 00:00:00 2001
From: Reid Morrison <reidmo@gmail.com>
Date: Fri, 8 Jan 2021 14:57:28 -0500
Subject: [PATCH 3/7] Fix tests

---
 active_record_replica.gemspec | 2 +-
 test/test_helper.rb           | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/active_record_replica.gemspec b/active_record_replica.gemspec
index 4ed0f1b..6e1d8f8 100644
--- a/active_record_replica.gemspec
+++ b/active_record_replica.gemspec
@@ -16,6 +16,6 @@ Gem::Specification.new do |spec|
   spec.files                 = Dir["lib/**/*", "LICENSE.txt", "Rakefile", "README.md"]
   spec.test_files            = Dir["test/**/*"]
   spec.license               = "Apache-2.0"
-  spec.required_ruby_version = ">= 2.5"
+  spec.required_ruby_version = ">= 2.3"
   spec.add_dependency "activerecord", ">= 4.2"
 end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 6eb33dd..2296cb8 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -49,11 +49,11 @@ def create_schema
   end
   ApplicationRecord.establish_connection(:test)
 else
-  ApplicationRecord.establish_connection(ActiveRecord::Base.configurations["test"]["replica"])
+  ActiveRecord::Base.establish_connection(ActiveRecord::Base.configurations["test"]["replica"])
   create_schema
 
   # Define Schema in primary database
-  ApplicationRecord.establish_connection(:test)
+  ActiveRecord::Base.establish_connection(:test)
   create_schema
 end
 

From 5736332370ef1396e6f9139ba79f17123024e3bc Mon Sep 17 00:00:00 2001
From: Reid Morrison <reidmo@gmail.com>
Date: Fri, 8 Jan 2021 15:32:19 -0500
Subject: [PATCH 4/7] Test fixes

---
 .travis.yml                | 3 +++
 Appraisals                 | 1 +
 Gemfile                    | 2 +-
 gemfiles/rails_4.2.gemfile | 2 +-
 test/test_helper.rb        | 6 +++---
 5 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index f2bb3b4..33db90f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -44,6 +44,9 @@ matrix:
     - name: "Rails 6.1 on Ruby 2.7.2"
       rvm: 2.7.2
       gemfile: gemfiles/rails_6.1.gemfile
+    - name: "Rails 6.1 on Ruby 3.0.0"
+      rvm: 3.0.0
+      gemfile: gemfiles/rails_6.1.gemfile
     - name: "Rails 6.1 on JRuby 9.2.14.0"
       rvm: jruby-9.2.14.0
       gemfile: gemfiles/rails_6.1.gemfile
diff --git a/Appraisals b/Appraisals
index 8a7bca0..dfdd250 100644
--- a/Appraisals
+++ b/Appraisals
@@ -3,6 +3,7 @@
 appraise "rails_4.2" do
   gem "activerecord", "~> 4.2.0"
   gem "activerecord-jdbcsqlite3-adapter", "~> 1.0", platform: :jruby
+  gem "sqlite3", "~> 1.3.6", platform: :ruby
 end
 
 appraise "rails_5.0" do
diff --git a/Gemfile b/Gemfile
index 8751a8c..716a371 100644
--- a/Gemfile
+++ b/Gemfile
@@ -14,4 +14,4 @@ gem "jdbc-sqlite3", platform: :jruby
 gem "sqlite3", platform: :ruby
 
 # gem "activerecord", "~> 5.2.0"
-gem "activerecord", "~> 6.0.3"
+gem "activerecord", "~> 6.1"
diff --git a/gemfiles/rails_4.2.gemfile b/gemfiles/rails_4.2.gemfile
index 830ac95..9f7b879 100644
--- a/gemfiles/rails_4.2.gemfile
+++ b/gemfiles/rails_4.2.gemfile
@@ -8,7 +8,7 @@ gem "rake"
 gem "activerecord-jdbcsqlite3-adapter", "~> 1.0", platform: :jruby
 gem "appraisal"
 gem "jdbc-sqlite3", platform: :jruby
-gem "sqlite3", platform: :ruby
+gem "sqlite3", "~> 1.3.6", platform: :ruby
 gem "activerecord", "~> 4.2.0"
 
 gemspec path: "../"
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 2296cb8..6cf3ba5 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -41,13 +41,13 @@ def create_schema
 # Define Schema in both databases.
 # Note: This is for testing purposes only and not needed by a Rails app.
 if ActiveRecord::VERSION::MAJOR >= 6
-  ApplicationRecord.connected_to(database: :primary_reader) do
+  ActiveRecord::Base.connected_to(database: :primary_reader) do
     create_schema
   end
-  ApplicationRecord.connected_to(database: :primary) do
+  ActiveRecord::Base.connected_to(database: :primary) do
     create_schema
   end
-  ApplicationRecord.establish_connection(:test)
+  ActiveRecord::Base.establish_connection(:test)
 else
   ActiveRecord::Base.establish_connection(ActiveRecord::Base.configurations["test"]["replica"])
   create_schema

From 25df55e523f9c739b0a5dfb0864458d412d062dd Mon Sep 17 00:00:00 2001
From: Reid Morrison <reidmo@gmail.com>
Date: Tue, 12 Jan 2021 11:48:16 -0500
Subject: [PATCH 5/7] Make reader_connection replaceable

---
 lib/active_record_replica/extensions.rb | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/active_record_replica/extensions.rb b/lib/active_record_replica/extensions.rb
index 472b657..79d204d 100644
--- a/lib/active_record_replica/extensions.rb
+++ b/lib/active_record_replica/extensions.rb
@@ -22,11 +22,15 @@ def active_record_replica_select(select_method, sql, name = nil, *args)
             public_send(select_method, sql, "Replica: #{name || 'SQL'}", *args)
           else
             ActiveRecord::Base.connected_to(role: ActiveRecord::Base.reading_role) do
-              ActiveRecord::Base.connection.public_send(select_method, sql, "Replica: #{name || 'SQL'}", *args)
+              reader_connection.public_send(select_method, sql, "Replica: #{name || 'SQL'}", *args)
             end
           end
         end
       end
+
+      def reader_connection
+        ActiveRecord::Base.connection
+      end
     else
       def active_record_replica_select(select_method, sql, name = nil, *args)
         ActiveRecordReplica.read_from_primary do

From f8b2f2b73a287acb52af563cd5f6cf6ebd2fb590 Mon Sep 17 00:00:00 2001
From: Reid Morrison <reidmo@gmail.com>
Date: Mon, 1 Feb 2021 14:14:23 -0500
Subject: [PATCH 6/7] Support Ruby 3.0

---
 lib/active_record_replica/extensions.rb | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/lib/active_record_replica/extensions.rb b/lib/active_record_replica/extensions.rb
index 79d204d..58d2fa9 100644
--- a/lib/active_record_replica/extensions.rb
+++ b/lib/active_record_replica/extensions.rb
@@ -7,22 +7,22 @@ module Extensions
 
     %i[select select_all select_one select_rows select_value select_values].each do |select_method|
       class_eval <<~RUBY, __FILE__, __LINE__ + 1
-        def #{select_method}(sql, name = nil, *args)
+        def #{select_method}(*args, **kargs)
           return super if active_record_replica_read_from_primary?
 
-          active_record_replica_select(:#{select_method}, sql, name, *args)
+          active_record_replica_select(:#{select_method}, *args, **kargs)
         end
       RUBY
     end
 
     if ActiveRecord::VERSION::MAJOR >= 6
-      def active_record_replica_select(select_method, sql, name = nil, *args)
+      def active_record_replica_select(select_method, sql, name = nil, *args, **kargs)
         ActiveRecordReplica.read_from_primary do
           if ActiveRecord::Base.current_role == ActiveRecord::Base.reading_role
-            public_send(select_method, sql, "Replica: #{name || 'SQL'}", *args)
+            public_send(select_method, sql, "Replica: #{name || 'SQL'}", *args, **kargs)
           else
             ActiveRecord::Base.connected_to(role: ActiveRecord::Base.reading_role) do
-              reader_connection.public_send(select_method, sql, "Replica: #{name || 'SQL'}", *args)
+              reader_connection.public_send(select_method, sql, "Replica: #{name || 'SQL'}", *args, **kargs)
             end
           end
         end

From 8417fefe9a501381b2d5c95d7c901060defeea97 Mon Sep 17 00:00:00 2001
From: Reid Morrison <reidmo@gmail.com>
Date: Thu, 4 Feb 2021 14:58:34 -0500
Subject: [PATCH 7/7] So many different combinations of Rails and Ruby ...

---
 Appraisals                              |  4 ++-
 gemfiles/rails_5.0.gemfile              |  6 ++--
 lib/active_record_replica/extensions.rb | 43 +++++++++++++++++++++++--
 3 files changed, 46 insertions(+), 7 deletions(-)

diff --git a/Appraisals b/Appraisals
index dfdd250..84b9c75 100644
--- a/Appraisals
+++ b/Appraisals
@@ -7,7 +7,9 @@ appraise "rails_4.2" do
 end
 
 appraise "rails_5.0" do
-  gem "activerecord", "~> 5.0"
+  gem "activerecord", "~> 5.0.0"
+  gem "activerecord-jdbcsqlite3-adapter", "~> 1.0", platform: :jruby
+  gem "sqlite3", "~> 1.3.6", platform: :ruby
 end
 
 appraise "rails_5.1" do
diff --git a/gemfiles/rails_5.0.gemfile b/gemfiles/rails_5.0.gemfile
index 59ea279..1095e8e 100644
--- a/gemfiles/rails_5.0.gemfile
+++ b/gemfiles/rails_5.0.gemfile
@@ -5,10 +5,10 @@ source "https://rubygems.org"
 gem "amazing_print"
 gem "minitest"
 gem "rake"
-gem "activerecord-jdbcsqlite3-adapter", platform: :jruby
+gem "activerecord-jdbcsqlite3-adapter", "~> 1.0", platform: :jruby
 gem "appraisal"
 gem "jdbc-sqlite3", platform: :jruby
-gem "sqlite3", platform: :ruby
-gem "activerecord", "~> 5.0"
+gem "sqlite3", "~> 1.3.6", platform: :ruby
+gem "activerecord", "~> 5.0.0"
 
 gemspec path: "../"
diff --git a/lib/active_record_replica/extensions.rb b/lib/active_record_replica/extensions.rb
index 58d2fa9..9a2cb0c 100644
--- a/lib/active_record_replica/extensions.rb
+++ b/lib/active_record_replica/extensions.rb
@@ -5,18 +5,49 @@ module ActiveRecordReplica
   module Extensions
     extend ActiveSupport::Concern
 
-    %i[select select_all select_one select_rows select_value select_values].each do |select_method|
+    no_keyword_args = %i[select select_one select_rows select_value select_values]
+    keyword_args = []
+
+    if ActiveRecord::VERSION::MAJOR >= 5
+      keyword_args << :select_all
+    else
+      no_keyword_args << :select_all
+    end
+
+    no_keyword_args.each do |select_method|
+      class_eval <<~RUBY, __FILE__, __LINE__ + 1
+        def #{select_method}(*args)
+          return super if active_record_replica_read_from_primary?
+
+          active_record_replica_select(:#{select_method}, *args)
+        end
+      RUBY
+    end
+
+    keyword_args.each do |select_method|
       class_eval <<~RUBY, __FILE__, __LINE__ + 1
         def #{select_method}(*args, **kargs)
           return super if active_record_replica_read_from_primary?
 
-          active_record_replica_select(:#{select_method}, *args, **kargs)
+          active_record_replica_select_kargs(:#{select_method}, *args, **kargs)
         end
       RUBY
     end
 
     if ActiveRecord::VERSION::MAJOR >= 6
-      def active_record_replica_select(select_method, sql, name = nil, *args, **kargs)
+      def active_record_replica_select(select_method, sql, name = nil, *args)
+        ActiveRecordReplica.read_from_primary do
+          if ActiveRecord::Base.current_role == ActiveRecord::Base.reading_role
+            public_send(select_method, sql, "Replica: #{name || 'SQL'}", *args)
+          else
+            ActiveRecord::Base.connected_to(role: ActiveRecord::Base.reading_role) do
+              reader_connection.public_send(select_method, sql, "Replica: #{name || 'SQL'}", *args)
+            end
+          end
+        end
+      end
+
+      def active_record_replica_select_kargs(select_method, sql, name = nil, *args, **kargs)
         ActiveRecordReplica.read_from_primary do
           if ActiveRecord::Base.current_role == ActiveRecord::Base.reading_role
             public_send(select_method, sql, "Replica: #{name || 'SQL'}", *args, **kargs)
@@ -38,6 +69,12 @@ def active_record_replica_select(select_method, sql, name = nil, *args)
         end
       end
 
+      def active_record_replica_select_kargs(select_method, sql, name = nil, *args, **kargs)
+        ActiveRecordReplica.read_from_primary do
+          reader_connection.public_send(select_method, sql, "Replica: \#{name || 'SQL'}", *args, **kargs)
+        end
+      end
+
       def reader_connection
         Replica.connection
       end