100 lines
3.1 KiB
Ruby
100 lines
3.1 KiB
Ruby
# frozen_string_literal: true
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require "rails/generators"
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require "rails/generators/active_record"
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module PaperTrail
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# Installs PaperTrail in a rails app.
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class InstallGenerator < ::Rails::Generators::Base
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include ::Rails::Generators::Migration
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# Class names of MySQL adapters.
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# - `MysqlAdapter` - Used by gems: `mysql`, `activerecord-jdbcmysql-adapter`.
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# - `Mysql2Adapter` - Used by `mysql2` gem.
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MYSQL_ADAPTERS = [
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"ActiveRecord::ConnectionAdapters::MysqlAdapter",
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"ActiveRecord::ConnectionAdapters::Mysql2Adapter"
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].freeze
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source_root File.expand_path("templates", __dir__)
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class_option(
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:with_changes,
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type: :boolean,
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default: false,
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desc: "Store changeset (diff) with each version"
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)
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desc "Generates (but does not run) a migration to add a versions table."
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def create_migration_file
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add_paper_trail_migration("create_versions")
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add_paper_trail_migration("add_object_changes_to_versions") if options.with_changes?
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end
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def self.next_migration_number(dirname)
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::ActiveRecord::Generators::Base.next_migration_number(dirname)
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end
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protected
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def add_paper_trail_migration(template)
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migration_dir = File.expand_path("db/migrate")
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if self.class.migration_exists?(migration_dir, template)
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::Kernel.warn "Migration already exists: #{template}"
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else
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migration_template(
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"#{template}.rb.erb",
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"db/migrate/#{template}.rb",
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item_type_options: item_type_options,
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migration_version: migration_version,
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versions_table_options: versions_table_options
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)
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end
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end
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private
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# MySQL 5.6 utf8mb4 limit is 191 chars for keys used in indexes.
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# See https://github.com/paper-trail-gem/paper_trail/issues/651
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def item_type_options
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opt = { null: false }
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opt[:limit] = 191 if mysql?
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", #{opt}"
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end
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def migration_version
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major = ActiveRecord::VERSION::MAJOR
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if major >= 5
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"[#{major}.#{ActiveRecord::VERSION::MINOR}]"
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end
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end
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def mysql?
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MYSQL_ADAPTERS.include?(ActiveRecord::Base.connection.class.name)
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end
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# Even modern versions of MySQL still use `latin1` as the default character
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# encoding. Many users are not aware of this, and run into trouble when they
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# try to use PaperTrail in apps that otherwise tend to use UTF-8. Postgres, by
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# comparison, uses UTF-8 except in the unusual case where the OS is configured
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# with a custom locale.
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#
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# - https://dev.mysql.com/doc/refman/5.7/en/charset-applications.html
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# - http://www.postgresql.org/docs/9.4/static/multibyte.html
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#
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# Furthermore, MySQL's original implementation of UTF-8 was flawed, and had
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# to be fixed later by introducing a new charset, `utf8mb4`.
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#
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# - https://mathiasbynens.be/notes/mysql-utf8mb4
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# - https://dev.mysql.com/doc/refman/5.5/en/charset-unicode-utf8mb4.html
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#
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def versions_table_options
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if mysql?
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', { options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci" }'
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else
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""
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end
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end
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end
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end
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