Sinatra, select from Datamapper pass to Haml

Question

I'm doing a brief exercise, condensed below. The issue I'm having is that I'm able to pass a selection of all tickets, but not a selection of one ticket. At / there is no problem listing all the tickets, at endpoint for a ticket I get:

NoMethodError at /pi2l9ulnw undefined method `slug' for #

I'm relatively new to Ruby and cutting and pasting, but it seems passing @ticket to get @ticket.slug is right from the Sinatra documentation. I've gotten to this point and reached an impasse where I am trying to create a simple endpoint for 1 ticket. Any suggestions while I try to read what I'm doing, thanks.

Example below condensed to 1 file:

require 'rubygems'
require 'sinatra'
require 'haml'
require 'dm-core'
require 'dm-validations'
require 'dm-types'
require 'dm-migrations'
require 'sqlite3'

configure do
class Ticket
  include DataMapper::Resource

  property :id, Serial                                   # unique key
  property :slug, String                                 # unique slug as endpoint  
  property :created_at, DateTime                         # created
  property :content, Text                                # content of ticket

  validates_uniqueness_of :slug
end

  set :sessions , true
  DataMapper::Logger.new($stdout, :debug)
  DataMapper.setup( :default , "sqlite3://#{Dir.pwd}/development.sqlite3" )  
  DataMapper.finalize
  DataMapper.auto_upgrade!
end

error do
  e = request.env['sinatra.error']
  Kernel.puts e.backtrace.join("\n")
  'Application error'
end

helpers do
  def sluggenerate
     rand(2**256).to_s(36)[0..8]
  end
end


get '/' do
    @tickets = Ticket.all(:order => [ :created_at.desc ])
    haml :index
end

get '/new' do
    haml :new
end

post '/new' do
  p params
  @ticket = Ticket.new(:slug => sluggenerate,:content => params[:content])
    if @ticket.save
        redirect '/'
    else
        redirect '/new'
    end
end

get '/:slug' do
    @ticket=Ticket.find(params[:slug])
    haml :ticket
end

__END__

@@ layout
%html
 = yield

@@ new
%h1 NEW TICKET
%form{:action => '/new', :method => 'post'}
  %p
    %input{:type => "text", :name => "content", :id => "content" }
    %input{:type => "submit", :value => "post"}

@@ index
%div{:class => "tickets"}
 - @tickets.each do |ticket|
  %div{:class => "ticket"}
   %h2
    %a{:href => "/#{ticket.slug}" }
     = ticket.slug
    %div{:class => "tickettime"}
     = ticket.created_at
    %div{:class => "ticketcontent"}
     = ticket.content

@@ ticket
%div{:class => "ticket"}
  = @ticket.slug

Answer 1

Changed

@@ ticket
%div{:class => "ticket"}
  = @ticket.slug

to

@@ ticket
%div{:class => "ticket"}
- @ticket.each do |ticket|
 %h1
  = ticket.slug

and it works

Answer 2

Perhaps the issue is with the construction of the model and querying with DM (there is basic info on the site, but looking further for info has been scary to say the least -pages of rdoc classes and methods that don't point anywhere for the basic level I'm at)

Ticket.get(params[:slug]) gives some sort of null error -- the query pulls nothing, maybe 'slug' needs to be made into some sort of key?

Answer 3

get '/:slug' do @ticket=Ticket.first(:slug=>params[:slug]) haml '%h1= @ticket.slug' end

and variations render perfectly, so part of the issue may be improper querying with DM

Answer 4

The answer was mostly in the datamapper query.

Insanely helpful, discovered after the fact:

http://cheat.errtheblog.com/s/datamapper/

the end of this issue, maybe useful to someone else