Sinatra and DataMapper Association

I want to make a blog application in Sinatra and DataMapper, my main application file is like this.

%w[rubygems sinatra data_mapper].each{ |r| require r }

DataMapper.setup(:default , ENV['DATABASE_URL'] || "sqlite3://#{Dir.pwd}/de开发者_如何学运维velopment.db")

class Post
  include DataMapper::Resource

  property :id,     Serial
  property :title,  String
  property :author,  String
  property :body,   Text

  has n, :comments
end

class Comment
  include DataMapper::Resource

  property :id,     Serial
  property :post_id,     Serial
  property :name,   String
  property :body,   Text

  belongs_to :post
end

helpers do
  def admin?
    request.cookies[settings.username] == settings.token
  end

  def protected!
    halt [401, 'Not Authorized'] unless admin?
  end
end


post '/comment/create' do
  comment = Comment.new(:name => params[:name], :body => params[:body])
  if comment.save
    status 201
    redirect '/post/'+post.id.to_s
  else
    status 412
    redirect '/'
  end
end

get '/post/:id' do
  @post = Post.get(params[:id])
  @comments = Comment.new
  erb :post
end

delete '/comment/:id' do
  Post.get(params[:id]).Comment.(params[:id]).destroy
  redirect '/post/'+post.id.to_s
end

DataMapper.auto_upgrade!

Now, my problem is how to set up the instance variable of comments in the post show file, to make, delete, and show the comments.

Any suggestion and solutions would be welcomed.

---

If I understand your question, you already most everything you need. Your post.erb file could look something like:

<h1><%= @post.title %></h1>
<%= @post.body %>

<% @post.comments.each do |comment| %>
  <p><%= comment.name %><br /><%= comment.body %></p>

  <form action="/comment/<%= comment.id %>" method="post">
    <input type="hidden" name="_method" value="delete" />
    <input type="submit" value="Delete comment">
  </form>
<% end %>

To create new comments, simply add a POST form with the right fields that points to your /comments/create route.

The reason I have that form with the "Delete" button in there is because your "delete '/comment/:id'" will be looking for the HTTP DELETE method. Unfortunately browsers don't actually implement that. Looking for a "_method" field in a POST form is how Sinatra/Rails/Rack apps get around that. Then, near the top of your Sinatra app, you have to tell it to look for that "_method" field with:

use Rack::MethodOverride

Hopefully that's what you were asking.