Dirk.Net

The basic task is to create a frontend for the encoding titans ffmpeg and mencoder and on Windows there’s the (otherwise) super Super. If if already arrived on Linux you should check out WinFF by Matt Weatherford (Big Matt).  Easy-to-use, fast and effiecient describe this neat little program.

Say you have an ActiveRecord model with a custom primary key and no field named “id”, a common occurrence when working with legacy data:

hotel.rb

class Hotel < ActiveRecord::Base
  set_primary_key :hotel_id

 (…)

Now you have the pertinent form

<% form_for(@hotel) do |f| %>
  <%= f.error_messages %>
  <p>
    <%= f.label ‘Hotel ID’ %>:
    <%= f.text_field :hotel_id %>
  </p>
  <p>
    <%= f.label ‘Name’ %>:
    <%= f.text_field :name %>
  </p>
<p>
    <%= f.label ‘Destination ID’ %>:
    <%= f.text_field :destination_id %>
  </p>

  <p>
    <%= f.submit ‘Save’ %>
  </p>
<% end %>

and default controller code:

hotels_controller.rb 

def create
    @hotel = Hotel.new(params[:hotel])

    respond_to do |format|

if @hotel.save

(…)

However, this won’t work. The mass assignment at

@hotel = Hotel.new(params[:hotel])

can’t be used with a “custom” primary key as this code called by the initializer excludes the primary key:

active_record/base.rb

def attributes_from_column_definition
        self.class.columns.inject({}) do |attributes, column|
          attributes[column.name] = column.default unless column.name == self.class.primary_key
          attributes
        end
      end

It is therefore necessary to call the initializer (Hotel.new) without the params hash and set the attributes manually:

hotel_controller.rb 

def create
    @hotel = Hotel.new
    my_params = params[:hotel]
    @hotel.hotel_id = my_params[:hotel_id]
    @hotel.name_english = my_params[:name]
    @hotel.destination_id = my_params[:destination_id]

 respond_to do |format|
      if @hotel.save

(…)