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This week, we're updating our course layouts and descriptions. Presentation and materials always gently change over time, but just occasionally there's a need to make a step change to clear out some of the old and roll in the new. That's now happening - but over a long and complex site it's not instant and you'll see sections of the site changing up to and including 19th September.

See also [here] for status update
 
Multiple views in a single appication - sharing common parts of the template - Ruby on Rails

So far ... we have installed Rails, and written a simple application with a single model, controller and view. In this article, I'll show you how to add a second controller method, and view, while sharing much of the view template. The example takes the scenario of a database of products where you can display either a summary listing of all the products, or all the details of a single product.

For multiple diplays

1. Added method(s) to controller, with links between

The modified code becomes:

  def index
    @main_result = "Gypsy recomends the Squirrel Pie"
    stockdata = Product.all
    @info = "<br />"
    for stock in stockdata
      @info += "<a href=\"single?name=#{stock.pname}\">[L]</a> " + stock.pname + " ... " + "<br />"
    end
  end
  
  def single
    @main_result = "<a href=/productlister/>[all]</a>"
    stockdata = Product.all
    @info = "<br />"
    stockdata.each do |stock|
      if stock.pname == params[:name] # Params is from a "form"
        @info += stock.pname + " full record " + "
"
      end
    end
  end


2. Added an overall layout for every view

This file is app/views/layouts/productlister.erb

  <html>
  <head>
  </head>
  <body>
  This is the general template for all productlister application pages
  <hr />
  <%= yield %>
  <hr />
  Copyright and common stuff!
  </body>
  </html>


3. REDUCED the index.erb to contain only the bits that differ on different pages

  <h1>All records report</h1>
  Here is a message: <b><%= @main_result %></b><br /><br />
  Here are the available products: <b><%= @info %></b><br /><br />


and add single.erb to contain the different VIEW bits for the single page

  <h1>Single Record Report</h1>
  To revert to product list: <b><%= @main_result %></b><br /><br />
  All about this product: <b><%= @info %></b><br /><br />


To note:

a) use of params to pick up from form

b) The main template for all output pages is now app/views/layouts/productlister.erb and app/views/productlister/index.erb has become a subsidiary pulled in by <%= yield %>

Diagram shows how the view selection works - for our application called productlister and two views called single and index.

1. Black line; if there is a file called /app/views/layouts/productlister.erb then THAT file will be used, filling in at the request to yield with app/views/productlister/single.erb or app/views/productlister/index.erb.

2. Red line; if there is NOT a file called /app/views/layouts/productlister.erb, then the file app/views/productlister/single.erb or app/views/productlister/index.erb will be used.

The idea is that the application wide part of the view goes in the file in the layouts directory, and the part of the view that only applies to some of the controllers goes in the directory for the application under the name of the controller method.

Note, though that we can also use render and redirect methods in our controller to influence or change this behaviour.


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


(written 2012-06-23)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
R202 - Ruby on Rails
  [4013] Web Frameworks - nested templates - (2013-02-22)
  [4010] Really Simple Rails - (2013-02-17)
  [3919] What is a web framework? - (2012-11-10)
  [3780] Ruby of Rails - cleanly displaying model data in the view - (2012-06-23)
  [3779] Adding validation to form entries and sticky fields - Ruby on Rails - (2012-06-23)
  [3778] Providing a form to allow the user to add data to the model - Ruby on Rails - (2012-06-23)
  [3772] Hello World - Ruby on Rails - a checklist of each step - (2012-06-22)
  [3756] Ruby on Rails - how it flows, and where the files go - (2012-06-08)
  [3624] Why do we need a Model, View, Controller architecture? - (2012-02-25)
  [2609] Scope of variables - important to Ruby on Rails - (2010-01-31)
  [2607] Answers on Ruby on Rails - (2010-01-30)
  [2605] Ruby on Rails - a sample application to teach you how - (2010-01-30)
  [1745] Moodle, Drupal, Django (and Rails) - (2008-08-08)
  [1375] Python v Ruby - (2007-10-02)
  [1302] Ruby, Ruby, Ruby. Rails, Rails, Rails. - (2007-08-13)
  [1050] The HTML++ Metalanguage - (2007-01-22)


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Providing a form to allow the user to add data to the model - Ruby on Rails
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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