如何使用MySQL和Ruby on Rails开发一个简单的留言板功能

rails new message_board
cd message_board

development:
  adapter: mysql2
  encoding: utf8mb4
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  username: your_mysql_username
  passWord: your_mysql_password
  database: message_board_development
  host: localhost

rails generate model Message content:text

class CreateMessages < ActiveRecord::Migration[6.0]
  def change
    create_table :messages do |t|
      t.text :content

      t.timestamps
    end
  end
end

rails db:migrate

rails generate controller Messages

class MessagesController < ApplicationController
  def index
    @messages = Message.all
  end

  def create
    @message = Message.new(message_params)

    if @message.save
      redirect_to messages_path
    else
      render :index
    end
  end

  private

  def message_params
    params.require(:message).permit(:content)
  end
end

Rails.application.routes.draw do
  resources :messages, only: [:index, :create]
  root to: "messages#index"
end

<h1>留言板</h1>

<% if @messages.any? %>
  <% @messages.each do |message| %>
    <div>
      <%= message.content %>
    </div>
  <% end %>
<% else %>
  <div>尚无留言</div>
<% end %>

<%= fORM_with model: Message.new, url: messages_path do |form| %>
  <%= form.text_area :content %>
  <%= form.submit "发表留言" %>
<% end %>

rails server