Giving erector a fair shake.

gistfile1.rbx

%w(rubygems dm-core dm-validations erector sinatra erb).each { |lib| require lib }

class Blog < Erector::Widget
  def initialize(err=false)
    @err = err
    super
  end
  
  def render
    html do
      head do
        title "A blog!"
        style(:type => 'text/css') { text "label { display: block; }" }
      end
      body do
        h1 "A blog!"
        p "Couldn't save!" if @err
        Post.all.each do |this|
          h3 this.title
          p this.body
        end
        small "no posts here!" if Post.all.empty?
        form(:action => '/create', :method => 'post') do
          p label_and_field 'title'
          p label_and_field 'body', :textarea
          p { input :type => 'submit', :value => 'Create!' }
        end
      end
    end
  end
  
  def label_and_field(name, tag=:input)
    label(:for => name) { text "#{name}:" }
    block_given? ? yield : send(tag, :name => name)
  end
end
 
# Blogs need posts
class Post
  include DataMapper::Resource
  property :id, Integer, :serial => true
  property :title, String, :nullable => false
  property :body, Text, :nullable => false
end
 
# Setup stuff that only runs once
configure do
  DataMapper.setup(:default, 'sqlite3:db.sqlite3')
  Post.auto_migrate!
end
 
# The actions
 
get '/' do
  Blog.new(params[:err]).to_s
end
 
post '/create' do
  p = Post.new params
  puts p.inspect
  redirect p.save ? '/' : '/?err=1'
end