Merge pull request #950 from airblade/fix_949

Improvements to migrations

CHANGELOG.md

@@ -11,11 +11,12 @@ recommendations of [keepachangelog.com](http://keepachangelog.com/).
 
 ### Added
 
-- None
+- Generate cleaner migrations for databases other than MySQL
 
 ### Fixed
 
-- None
+- [#949](https://github.com/airblade/paper_trail/issues/949) - Inherit from the
+  new versioned migration class, e.g. `ActiveRecord::Migration[5.1]`
 
 ## 7.0.0 (2017-04-01)
 

lib/generators/paper_trail/install_generator.rb

@@ -6,6 +6,14 @@ module PaperTrail
   class InstallGenerator < ::Rails::Generators::Base
     include ::Rails::Generators::Migration
 
+    # Class names of MySQL adapters.
+    # - `MysqlAdapter` - Used by gems: `mysql`, `activerecord-jdbcmysql-adapter`.
+    # - `Mysql2Adapter` - Used by `mysql2` gem.
+    MYSQL_ADAPTERS = [
+      "ActiveRecord::ConnectionAdapters::MysqlAdapter",
+      "ActiveRecord::ConnectionAdapters::Mysql2Adapter"
+    ].freeze
+
     source_root File.expand_path("../templates", __FILE__)
     class_option(
       :with_changes,
@@ -50,7 +58,57 @@ module PaperTrail
       if self.class.migration_exists?(migration_dir, template)
         ::Kernel.warn "Migration already exists: #{template}"
       else
-        migration_template "#{template}.rb", "db/migrate/#{template}.rb"
+        migration_template(
+          "#{template}.rb.erb",
+          "db/migrate/#{template}.rb",
+          item_type_options: item_type_options,
+          migration_version: migration_version,
+          versions_table_options: versions_table_options
+        )
+      end
+    end
+
+    private
+
+    # MySQL 5.6 utf8mb4 limit is 191 chars for keys used in indexes.
+    # See https://github.com/airblade/paper_trail/issues/651
+    def item_type_options
+      opt = { null: false }
+      opt[:limit] = 191 if mysql?
+      ", #{opt}"
+    end
+
+    def migration_version
+      major = ActiveRecord::VERSION::MAJOR
+      if major >= 5
+        "[#{major}.#{ActiveRecord::VERSION::MINOR}]"
+      end
+    end
+
+    def mysql?
+      MYSQL_ADAPTERS.include?(ActiveRecord::Base.connection.class.name)
+    end
+
+    # Even modern versions of MySQL still use `latin1` as the default character
+    # encoding. Many users are not aware of this, and run into trouble when they
+    # try to use PaperTrail in apps that otherwise tend to use UTF-8. Postgres, by
+    # comparison, uses UTF-8 except in the unusual case where the OS is configured
+    # with a custom locale.
+    #
+    # - https://dev.mysql.com/doc/refman/5.7/en/charset-applications.html
+    # - http://www.postgresql.org/docs/9.4/static/multibyte.html
+    #
+    # Furthermore, MySQL's original implementation of UTF-8 was flawed, and had
+    # to be fixed later by introducing a new charset, `utf8mb4`.
+    #
+    # - https://mathiasbynens.be/notes/mysql-utf8mb4
+    # - https://dev.mysql.com/doc/refman/5.5/en/charset-unicode-utf8mb4.html
+    #
+    def versions_table_options
+      if mysql?
+        ', { options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci" }'
+      else
+        ""
       end
     end
   end

lib/generators/paper_trail/templates/create_versions.rb

@@ -1,80 +0,0 @@
-# This migration creates the `versions` table, the only schema PT requires.
-# All other migrations PT provides are optional.
-class CreateVersions < ActiveRecord::Migration
-  # Class names of MySQL adapters.
-  # - `MysqlAdapter` - Used by gems: `mysql`, `activerecord-jdbcmysql-adapter`.
-  # - `Mysql2Adapter` - Used by `mysql2` gem.
-  MYSQL_ADAPTERS = [
-    "ActiveRecord::ConnectionAdapters::MysqlAdapter",
-    "ActiveRecord::ConnectionAdapters::Mysql2Adapter"
-  ].freeze
-
-  # The largest text column available in all supported RDBMS is
-  # 1024^3 - 1 bytes, roughly one gibibyte.  We specify a size
-  # so that MySQL will use `longtext` instead of `text`.  Otherwise,
-  # when serializing very large objects, `text` might not be big enough.
-  TEXT_BYTES = 1_073_741_823
-
-  def change
-    create_table :versions, versions_table_options do |t|
-      t.string   :item_type, item_type_options
-      t.integer  :item_id,   null: false
-      t.string   :event,     null: false
-      t.string   :whodunnit
-      t.text     :object, limit: TEXT_BYTES
-
-      # Known issue in MySQL: fractional second precision
-      # -------------------------------------------------
-      #
-      # MySQL timestamp columns do not support fractional seconds unless
-      # defined with "fractional seconds precision". MySQL users should manually
-      # add fractional seconds precision to this migration, specifically, to
-      # the `created_at` column.
-      # (https://dev.mysql.com/doc/refman/5.6/en/fractional-seconds.html)
-      #
-      # MySQL users should also upgrade to rails 4.2, which is the first
-      # version of ActiveRecord with support for fractional seconds in MySQL.
-      # (https://github.com/rails/rails/pull/14359)
-      #
-      t.datetime :created_at
-    end
-    add_index :versions, %i(item_type item_id)
-  end
-
-  private
-
-  # MySQL 5.6 utf8mb4 limit is 191 chars for keys used in indexes.
-  # See https://github.com/airblade/paper_trail/issues/651
-  def item_type_options
-    opt = { null: false }
-    opt[:limit] = 191 if mysql?
-    opt
-  end
-
-  def mysql?
-    MYSQL_ADAPTERS.include?(connection.class.name)
-  end
-
-  # Even modern versions of MySQL still use `latin1` as the default character
-  # encoding. Many users are not aware of this, and run into trouble when they
-  # try to use PaperTrail in apps that otherwise tend to use UTF-8. Postgres, by
-  # comparison, uses UTF-8 except in the unusual case where the OS is configured
-  # with a custom locale.
-  #
-  # - https://dev.mysql.com/doc/refman/5.7/en/charset-applications.html
-  # - http://www.postgresql.org/docs/9.4/static/multibyte.html
-  #
-  # Furthermore, MySQL's original implementation of UTF-8 was flawed, and had
-  # to be fixed later by introducing a new charset, `utf8mb4`.
-  #
-  # - https://mathiasbynens.be/notes/mysql-utf8mb4
-  # - https://dev.mysql.com/doc/refman/5.5/en/charset-unicode-utf8mb4.html
-  #
-  def versions_table_options
-    if mysql?
-      { options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci" }
-    else
-      {}
-    end
-  end
-end

lib/generators/paper_trail/templates/create_versions.rb.erb

@@ -0,0 +1,36 @@
+# This migration creates the `versions` table, the only schema PT requires.
+# All other migrations PT provides are optional.
+class CreateVersions < ActiveRecord::Migration<%= migration_version %>
+
+  # The largest text column available in all supported RDBMS is
+  # 1024^3 - 1 bytes, roughly one gibibyte.  We specify a size
+  # so that MySQL will use `longtext` instead of `text`.  Otherwise,
+  # when serializing very large objects, `text` might not be big enough.
+  TEXT_BYTES = 1_073_741_823
+
+  def change
+    create_table :versions<%= versions_table_options %> do |t|
+      t.string   :item_type<%= item_type_options %>
+      t.integer  :item_id,   null: false
+      t.string   :event,     null: false
+      t.string   :whodunnit
+      t.text     :object, limit: TEXT_BYTES
+
+      # Known issue in MySQL: fractional second precision
+      # -------------------------------------------------
+      #
+      # MySQL timestamp columns do not support fractional seconds unless
+      # defined with "fractional seconds precision". MySQL users should manually
+      # add fractional seconds precision to this migration, specifically, to
+      # the `created_at` column.
+      # (https://dev.mysql.com/doc/refman/5.6/en/fractional-seconds.html)
+      #
+      # MySQL users should also upgrade to rails 4.2, which is the first
+      # version of ActiveRecord with support for fractional seconds in MySQL.
+      # (https://github.com/rails/rails/pull/14359)
+      #
+      t.datetime :created_at
+    end
+    add_index :versions, %i(item_type item_id)
+  end
+end

spec/generators/install_generator_spec.rb

@@ -15,14 +15,30 @@ RSpec.describe PaperTrail::InstallGenerator, type: :generator do
     end
 
     it "generates a migration for creating the 'versions' table" do
+      expected_parent_class = lambda {
+        old_school = "ActiveRecord::Migration"
+        ar_version = ActiveRecord::VERSION
+        if ar_version::MAJOR >= 5
+          format("%s[%d.%d]", old_school, ar_version::MAJOR, ar_version::MINOR)
+        else
+          old_school
+        end
+      }.call
+      expected_create_table_options = lambda {
+        if described_class::MYSQL_ADAPTERS.include?(ActiveRecord::Base.connection.class.name)
+          ', { options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci" }'
+        else
+          ""
+        end
+      }.call
       expect(destination_root).to(
         have_structure {
           directory("db") {
             directory("migrate") {
               migration("create_versions") {
-                contains "class CreateVersions"
+                contains("class CreateVersions < " + expected_parent_class)
                 contains "def change"
-                contains "create_table :versions"
+                contains "create_table :versions#{expected_create_table_options}"
               }
             }
           }

spec/generators/paper_trail/templates/create_versions_spec.rb

@@ -1,51 +0,0 @@
-require "rails_helper"
-require "generators/paper_trail/templates/create_versions"
-
-RSpec.describe CreateVersions do
-  describe "#change", verify_stubs: false do
-    let(:migration) { described_class.new }
-
-    before do
-      allow(migration).to receive(:add_index)
-      allow(migration).to receive(:create_table)
-    end
-
-    it "creates the versions table" do
-      migration.change
-      expect(migration).to have_received(:create_table) do |arg1|
-        expect(arg1).to eq(:versions)
-      end
-    end
-
-    case ENV["DB"]
-    when "mysql"
-      it "uses InnoDB engine" do
-        migration.change
-        expect(migration).to have_received(:create_table) do |_, arg2|
-          expect(arg2[:options]).to match(/ENGINE=InnoDB/)
-        end
-      end
-
-      it "uses utf8mb4 character set" do
-        migration.change
-        expect(migration).to have_received(:create_table) do |_, arg2|
-          expect(arg2[:options]).to match(/DEFAULT CHARSET=utf8mb4/)
-        end
-      end
-
-      it "uses utf8mb4_col collation" do
-        migration.change
-        expect(migration).to have_received(:create_table) do |_, arg2|
-          expect(arg2[:options]).to match(/COLLATE=utf8mb4_general_ci/)
-        end
-      end
-    else
-      it "passes an empty options hash to create_table" do
-        migration.change
-        expect(migration).to have_received(:create_table) do |_, arg2|
-          expect(arg2).to eq({})
-        end
-      end
-    end
-  end
-end