创建一个ruby on rails API，以便与已经完成的php系统共享mysql数据库。

rails new MyRailsAPI --api --database=mysql

default: &default
  adapter: mysql2
  encoding: utf8mb4
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  username: your_mysql_username
  password: your_mysql_password
  socket: /var/run/mysqld/mysqld.sock

development:
  <<: *default
  database: my_rails_api_dev

test:
  <<: *default
  database: my_rails_api_test

production:
  <<: *default
  database: my_rails_api_prod
  username: my_rails_api
  password: <%= ENV['MY_RAILS_API_DATABASE_PASSWORD'] %>

mysql -u your_mysql_username -p

CREATE DATABASE my_rails_api_dev;
CREATE DATABASE my_rails_api_test;
CREATE DATABASE my_rails_api_prod;

rails db:migrate

rails generate model User id:integer name:string email:string

rails db:migrate

rails generate controller Api::Users index show create update destroy

Rails.application.routes.draw do
  namespace :api do
    resources :users, only: [:index, :show, :create, :update, :destroy]
  end
end

module Api
  class UsersController < ApplicationController
    before_action :set_user, only: [:show, :update, :destroy]

    # GET /api/users
    def index
      @users = User.all
      render json: @users
    end

    # GET /api/users/1
    def show
      render json: @user
    end

    # POST /api/users
    def create
      @user = User.new(user_params)
      if @user.save
        render json: @user, status: :created
      else
        render json: @user.errors, status: :unprocessable_entity
      end
    end

    # PUT/PATCH /api/users/1
    def update
      if @user.update(user_params)
        render json: @user
      else
        render json: @user.errors, status: :unprocessable_entity
      end
    end

    # DELETE /api/users/1
    def destroy
      @user.destroy
    end

    private
    # Use callbacks to share common setup or constraints between actions.
    def set_user
      @user = User.find(params[:id])
    end

    # Only allow a trusted parameter "white list" through.
    def user_params
      params.require(:user).permit(:name, :email)
    end
  end
end