I.NFECTIO.US

  def pdftest
    send_data(render_to_string(:action => 'pdftest', :layout => false),
      :filename => "pdftest.pdf", 
      :type => "application/pdf", 
      :disposition => "inline")
  end

<%

# Create the PDF object and reverse the coordinate system. By
# default, PDFs cartesian coordinate system starts with (0,0)
# in the lower left corner. By setting @topdown => true, we flip
# the coordinate system upside to make the upper left (0,0).
# You can also set default margins and page sizes during initialization
p = PDF.new(:topdown => true)

# When working with PDFs, the typical structure is a document 
# with many pages. Calling open begins what PDFlib refers to as
# document scope.
p.open

  # Our PDF only needs one page to display the book cover
  # so we'll open a new page here, and close it at the end
  p.beginpage

    # When working with PDFs, setting a base font/size is required 
    # before writing any text to the page. We wont use this font for
    # this page, but thats OK
    p.font('Helvetica', 10, '#000000')

    # Remember when I said we would tell PDFlib where to find
    # our images? Here ya go. Stick in the path to where you
    # copied rails.gif to.
    p.set_parameter('SearchPath', '/path/to/images')


    # Let the fun begin. We'll start out with the book outline.
    # Just gonna draw a black outline and fill it with white.
    # Using the rect method, this is easy to do. By passing
    # the stroke and fill colors, we tell the method to both
    # stroke and fill the path created.
    # def rect(x, y, w, h, options={})
    p.rect(p.left_margin,
           p.top_margin,
           p.page_width-(p.left_margin+p.right_margin),
           p.page_height-(p.top_margin+p.bottom_margin),
           :fillcolor => '#ffffff',
           :strokecolor => '#000000')
    
    # Next up is the maroon tab at the top of the book with 
    # the text 'The Pragmatic Programmers'. To draw out this
    # odd shape, we'll create a path and pass an multi-dimensional
    # array of points for the path to follow. This time, by only
    # specifiying a fillcolor, we are telling PDFlib not to stroke
    # the path, but only fill it.
    p.path([[102,p.top_margin],
            [312, p.top_margin],
            [300, p.top_margin+63],
            [114, p.top_margin+63]],
            :fillcolor => '#741415')
    
    # Time to add the text in the pretty maroon box we just made.
    # Here, we set the font we want to use ahead of time. Later,
    # I'll show you a different way to do it inline.
    p.font('Times-Roman', 16, '#ffffff')
    p.print 'The', 160, 51
    p.print 'Pragmatic', 151, 66
    p.print 'Programmers', 172, 80
        
    # For the Title of the Book, we demonstrate how we can
    # use pass-through options for native PDFlib functionality
    # not provided for in the wrapper. We are able to adjust
    # the charspacing and horizscaling by passing those options
    # as Hash elements and the wrapper library sends them onto
    # the native PDFlib method. This also demonstrates how
    # to set the font/fontsize inline on a single call to print
    p.font('Times-Roman', 60, '#000000')
    p.print 'Agile', 112, 230 
    p.print 'Web', 254, 230, :charspacing => -2
    p.print 'Development', 162, 278, :horizscaling => 105
    p.print 'with', 248, 308, :fontsize => 38
    p.print 'Rails', 322, 324, :horizscaling => 110
    
    # Working with images in PDFs is easy as you can see below.
    # Pass the name and location and walla, an image in your PDF.
    # Images can be used as templates for forms as well. If you have
    # complex line layouts, its easier to save an image version of the
    # raw template, then insert it as a background layer and write on
    # top of it.
    p.image 'rails.gif', 140, 330
    
    # In these print calls, we give the :boxsize of the textfield 
    # and specify the :position to obtain right aligned text.
    p.font('Courier-BoldOblique', 14)
    p.print 'Dave Thomas', 300, 600, :boxsize => '{205 20}', :position => '{right bottom}'
    p.print 'David Heinemeier Hansson', 300, 618, :boxsize => '{205 20}', :position => '{right bottom}'
    
    # Just another rectangle here for the footer of the cover.
    p.rect(p.left_margin, 
           p.page_height-p.bottom_margin-35,
           p.page_width-p.left_margin-p.right_margin,
           35,
           :fillcolor => '#741415')
    
    # Here we right align the text, set the fillcolor for the font,
    # and set the font/fontsize inline on the print call
    p.print 'The Facets of Ruby Series', 260, 754, :boxsize => '{310 20}', :position => '{right center}', :fillcolor => '#ffffff', :font => 'Times-Roman', :fontsize => 24
    
  p.endpage
p.close

# This next line actually sends the in-memory PDF back to the 
# controller as a string so that it can be sent to the browser.
%>

<%= p.read -%>

@model_a = ModelA.find(:all,
  :select => 'sum(column_a) as column_a, sum(column_b) as column_b, model_b.group_field', 
  :joins => 'inner join model_b on model_a.id = model_b.model_a_id', 
  :group => 'model_b.group_field', 
  :conditions => ['column_a=?', column_a_value],
  :readonly => true)

def set_travel_time(hours, minutes)
  self.travel_time = ((hours.to_f * 60) + minutes.to_i).to_i
end

def get_travel_time
  travel_time.to_i.divmod(60)
end

def create
  @model.new(...)
  ...
  @model.set_travel_time(params[:hours], params[:minutes])
  ...
  if @model.save
  ...
end

def edit
  @model = Model.find(...)
  ...
  @hours, @minutes = @model.get_travel_time
  ...
end

<%= text_field_tag 'hours', @hours -%> hours 
<%= text_field_tag 'minutes', @minutes -%> minutes 

  acts_as_nested_set :scope => :root
    
  def before_create
    # Update the child object with its parents attrs
    unless self[:parent_id].to_i.zero?
      self[:depth] = parent[:depth].to_i + 1
      self[:root_id] = parent[:root_id].to_i
    end
  end
  
  def after_create
    # Update the parent root_id with its id
    if self[:parent_id].to_i.zero?
      self[:root_id] = self[:id]
      self.save
    else
      parent.add_child self
    end
  end
  
  def parent
    @parent ||= self.class.find(self[:parent_id])
  end

create_table "my_table_name", :force => true do |t|
  t.column "root_id", :integer
  t.column "parent_id", :integer
  t.column "lft", :integer
  t.column "rgt", :integer
  t.column "depth", :integer
end

In controller.rb:

def create
  begin
    @client = Client.new(params[:client])
  # Catch the exception from AR::Base
  rescue ActiveRecord::MultiparameterAssignmentErrors => ex
    # Iterarate over the exceptions and remove the invalid field components from the input
    ex.errors.each { |err| params[:client].delete_if { |key, value| key =~ /^#{err.attribute}/ } }
    # Recreate the Model with the bad input fields removed
    @client = Client.new(params[:client])      
  end
    
  if @client.save
    flash[:notice] = 'Client was successfully created.'
    redirect_to :action => 'list'
  else
    render :action => 'new'
  end
end

In model.rb:

validates_presence_of :date_field_name, :message => 'must be a valid date'