20.9.2014 - We have just updated our course layouts and descriptions and added our 2015 schedule.
Adding validation to form entries and sticky fields - Ruby on Rails
So far, we have implemented an MVC application under Ruby in Rails, and provided a rudimentary form to allow the user to add rows to the model. In this section, we show you the extra code needed to validate the data, and to echo it back out to the user within the form if it's incorrect.
1. In the model, add some calls to provide criteria against which to validate
class Product < ActiveRecord::Base
2. In the controller, add code to see if the save of the new record worked
validates_presence_of :pname, :unitprice, :stocklevel
validates_numericality_of :unitprice, :stocklevel
3. Add the error messages to the view:
@newprod = Product.new(params[:product])
if @newprod.save # And checks the object
redirect_to :action => "index" # to method (above)
@main_result = "Please correct"
render :action => "addproduct" # using view
<% form_for(@newprod, :url => "/productlister/saveproduct") do |fieldname| %>
<%= fieldname.error_messages %>
<%= fieldname.label :pname %>
Name of product <%= fieldname.text_field :pname %><br />
<%= fieldname.label :unitprice %>
Price Each <%= fieldname.text_field :unitprice %><br />
<%= fieldname.label :stocklevel %>
Initial Stock Held <%= fieldname.text_field :stocklevel %><br />
<%= fieldname.submit "Done!" %><br />
<% end %><br />
| This is one of a series of summaries taking you from initial installation of Ruby and Rails through to a complete multitable application:|
[link] - Installing Ruby and Rails
[link] - Hello World, Ruby on Rails Style
[link] - What and Why - Model, View, Controller
[link] - Multiple views, same model
[link] - A form to allow data to be added to the model
[link] - Validating data entries for storage in the model
[link] - Cleanly viewing model data
[link] - Complete sample, including a multiple table model
These topics are covered on our Introduction to Rails day - an optional extension of Ruby Programming or Learning to program in Ruby
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articlesR202 - Ruby on Rails 
Web Frameworks - nested templates - (2013-02-22) 
Really Simple Rails - (2013-02-17) 
What is a web framework? - (2012-11-10) 
Ruby of Rails - cleanly displaying model data in the view - (2012-06-23) 
Providing a form to allow the user to add data to the model - Ruby on Rails - (2012-06-23) 
Multiple views in a single appication - sharing common parts of the template - Ruby on Rails - (2012-06-23) 
Hello World - Ruby on Rails - a checklist of each step - (2012-06-22) 
Ruby on Rails - how it flows, and where the files go - (2012-06-08) 
Why do we need a Model, View, Controller architecture? - (2012-02-25) 
Scope of variables - important to Ruby on Rails - (2010-01-31) 
Answers on Ruby on Rails - (2010-01-30) 
Ruby on Rails - a sample application to teach you how - (2010-01-30) 
Moodle, Drupal, Django (and Rails) - (2008-08-08) 
Python v Ruby - (2007-10-02) 
Ruby, Ruby, Ruby. Rails, Rails, Rails. - (2007-08-13) 
The HTML++ Metalanguage - (2007-01-22)
Some other Articles
Load path, load and require in Ruby, and a change from 1.8 to 1.9Standard methods available on all objects in RubyPrivate, Protected, Public in Ruby. What about interfaces and abstract classes in Ruby?Adding validation to form entries and sticky fields - Ruby on RailsSome traps it's so easy to fall into in designing your web siteAlan Turing - 1912 to 1954Melksham - a new dawn
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