MySQL

MySQL is supported by the core better_auth gem through the direct MySQL adapter. Rails applications can use better_auth-rails with ActiveRecord on top of MySQL.

Install Dependencies

gem "better_auth"
gem "mysql2"

bundle install

Example Usage

require "better_auth"

auth = BetterAuth.auth(
  secret: ENV.fetch("BETTER_AUTH_SECRET"),
  base_url: ENV.fetch("BETTER_AUTH_URL"),
  database: ->(options) {
    BetterAuth::Adapters::MySQL.new(
      options,
      url: ENV.fetch("DATABASE_URL")
    )
  }
)

You may also pass an existing Mysql2::Client when your app owns connection management.

require "mysql2"

client = Mysql2::Client.new(
  host: "localhost",
  username: "root",
  password: ENV.fetch("MYSQL_PASSWORD"),
  database: "app_development",
  symbolize_keys: false
)

auth = BetterAuth.auth(
  secret: ENV.fetch("BETTER_AUTH_SECRET"),
  database: ->(options) {
    BetterAuth::Adapters::MySQL.new(
      options,
      connection: client
    )
  }
)

Rails

Rails apps should normally use better_auth-rails and the ActiveRecord adapter.

gem "better_auth-rails"
gem "mysql2"

bin/rails generate better_auth:install
bin/rails db:migrate

Schema generation & migration

The Ruby schema helpers generate MySQL DDL from the same Better Auth configuration used at runtime, including plugins, custom model names, custom field names, and additional_fields.

config = BetterAuth::Configuration.new(
  secret: ENV.fetch("BETTER_AUTH_SECRET"),
  database: :memory,
  plugins: []
)

statements = BetterAuth::Schema::SQL.create_statements(
  config,
  dialect: :mysql
)

puts statements.join("\n\n")

require "better_auth"
require "mysql2"

config = BetterAuth::Configuration.new(
  secret: ENV.fetch("BETTER_AUTH_SECRET"),
  database: :memory,
  plugins: []
)

statements = BetterAuth::Schema::SQL.create_statements(
  config,
  dialect: :mysql
)

client = Mysql2::Client.new(
  host: "localhost",
  username: "root",
  password: ENV.fetch("MYSQL_PASSWORD"),
  database: "app_development",
  symbolize_keys: false
)
statements.each { |sql| client.query(sql) }

Joins (Experimental)

Enable experimental joins when you want Better Auth to ask the database adapter to fetch related records in one adapter call.

auth = BetterAuth.auth(
  secret: ENV.fetch("BETTER_AUTH_SECRET"),
  experimental: { joins: true },
  database: ->(options) {
    BetterAuth::Adapters::MySQL.new(
      options,
      url: ENV.fetch("DATABASE_URL")
    )
  }
)

The MySQL adapter supports native joins for core relationships and for plugin schema relationships declared with references. Rails uses generated ActiveRecord associations for the same schema-driven relationships.

Schema

The Ruby schema maps Better Auth logical fields to MySQL physical columns.

MySQL DDL uses InnoDB, utf8mb4, json for JSON-like fields, datetime(6) for date fields, and varchar(191) for indexed strings. Ids are generated as hex strings by default. Set advanced: { database: { generate_id: "uuid" } } to generate UUID strings instead.

Additional Information

• The direct adapter supports the shared Better Auth CRUD contract, where operators, sorting, pagination, counts, transactions, and native joins.
• If you pass your own Mysql2::Client, configure connection settings such as timezone/session behavior in that client before handing it to Better Auth.
• Rails apps should prefer Rails migrations generated by better_auth-rails; direct SQL generation is intended for non-Rails apps or custom migration workflows.