Rails 【今晚不翻车 20 点不见不散】如何不用框架用 Ruby 写 Web APP？

rocLv · April 20, 2022 · Last by Rei replied at April 30, 2022 · 1182 hits

前天做了一次分享，展示的很好，结果半路翻了一下车。。。

分享结束后，我又运行了一下代码，没毛病。。。好吧，暂且归为环境的问题

今晚 20 点准备给大家做第二次分享，《Ruby on Rails 源码框架导读》

我们首先不用任何框架，直接用 Rack 、erubi、sqlite3 构建一个 Web app。

本着不作不死的精神，今晚我又准备现场撸代码了

代码先贴在这里：

# config.ru
require "erubi"
$LOAD_PATH << '.'

module Simp
  class Application
    def self.call(env)
      [200, {"Content-Type" => "html"},
       [html(env["REQUEST_PATH"][1..-1])]
      ]
    end

    def self.render(file_name)
      eval Erubi::Engine.new(
        File.read("#{file_name}.html.erb")
      ).src
    end

    def self.render_400
      "Oops, the page you visited is not exist."
    end

    def self.html(file_name)
      root_path = '/Users/i/Code/iClean/P7RubyTraining/webapp'
      file_name = File.join(root_path, file_name)
      p file_name
      if File.exist?("#{file_name}.html.erb")
        render file_name
      else
        render_400
      end
    end
  end
end

run Simp::Application

index 页面代码

# index.html.erb

<%
$LOAD_PATH << '.'
require 'model'
@students = Student.all
p @students
%>
<html>
  <head>
    <title>Simp is not a web framework.</title>
  <head>
  <body>
    <table>
      <tr>
        <td>Name</td>
        <td>Email</td>
        <td>Grade</td>
        <td>Blog</td>
      </tr>

    <% @students.each do |student| %>
      <tr>
       <td><%= student['name'] %></td>
       <td><%= student['email'] %></td>
       <td><%= student['grade'] %></td>
       <td><%= student['blog'] %></td>
      </tr>
    <% end %>
    </table>
  </body>
</html>

# model.rb

require 'sqlite3'

class Student
  # Open a database
  DB = SQLite3::Database.new "test.db"

  def self.all
    @students = []

    DB.execute( "select * from students" ) do |row|
      student = {}
      student['name'], student['email'],
      student['grade'], student['blog'] = row
      @students << student
    end

    @students
  end

end

在运行前记得先生成数据库：

require "sqlite3"

# Open a database
db = SQLite3::Database.new "test.db"

# Create a table
rows = db.execute <<-SQL
  create table numbers (
    name varchar(30),
    val int
  );
SQL

# Execute a few inserts
{
  "one" => 1,
  "two" => 2,
}.each do |pair|
  db.execute "insert into numbers values ( ?, ? )", pair
end

# Find a few rows
db.execute( "select * from numbers" ) do |row|
  p row
end

# Create another table with multiple columns

db.execute <<-SQL
  create table students (
    name varchar(50),
    email varchar(50),
    grade varchar(5),
    blog varchar(50)
  );
SQL

# Execute inserts with parameter markers
db.execute("INSERT INTO students (name, email, grade, blog) 
            VALUES (?, ?, ?, ?)", ["Jane", "[email protected]", "A", "http://blog.janedoe.com"])

db.execute( "select * from students" ) do |row|
  p row
end