学了几天，尝试做一个简单的todo list

先建list.rb

    require "haml"
    require "sinatra"
    require "data_mapper"
    DataMapper.setup(:default,"sqlite3://#{Dir.pwd}/test.db")
    
    
    class List
        include DataMapper::Resource
        property :id, Serial
        property :name, String
        property :completed_at, DateTime
    end
    
    #index
    get '/' do 
            @lists = List.all
            haml :index 
    end
    
    #edit
    
    get '/list/:id' do
        @list = List.get(params[:id])
        haml :edit
    end
    
    #create
    
    post '/list/create' do  
        @list = List.create(name: params[:name]) 
        redirect '/'
    end
    
    #update
    
    put '/list/:id' do
        @list = List.get(params[:id])
        @list.name = params[:name]
        @list.save
        redirect '/'
    end
    
    #delete
    
    get '/list/:id/delete' do
        @list = List.get(params[:id])
        haml :delete
    end
    
    delete '/list/:id' do
        List.get(params[:id]).destroy
        redirect '/'
    end
    
    DataMapper.auto_upgrade!

建立config.ru

require "./list"
run Sinatra::Application

建立views文件夹，在views里添加layout.haml,index.haml,edit.haml,delete.haml

layout.haml

!!!
%html
%head
    %title TodoList
%body
    %h1 To Do List
    =yield

index.haml

%form{action:"/list/create",method:"POST"}
    %input{type:"text",name:"name",id:"name"}
    %input{type:"submit",value:"Add"}

%h1 Lists:
-unless @lists.nil?
    %ul
    -@lists.each do |list|
        %li
           %a{href:"/list/#{list.id}"}= list.name

edit.haml

 %form{action:"/list/#{@list.id}",method:"POST"}
     %input{name:"_method",type:"hidden",value:"put"}
     %input{type:"text",name:"name",id:"name",value:"#{@list.name}"}
     %input{type:"submit",name:"commit",id:"list_commit",value:"Update"}
     %a{href:"/list/#{@list.id}/delete"} Delete

delete.haml

 %h2= @list.name
 %h3 Are you sure?
 %form{action:"/list/#{@list.id}",method:"post"}
   %input{type:"hidden",name:"_method",value:"delete"}
   %input{type:"submit",value:"Delete"}
   or
   %a{href:'/'} Cancel  

最后运行

 ruby list.rb

试试吧