Four Days on Rails

belongs_to :category

validates_associated :category

validates_format_of :done_before_type_cast, :with => /[01]/, :message=>"must be 0 or 1"

validates_inclusion_of :priority, :in=>1..5, :message=>"must be between 1 (high) and 5 (low)"

validates_presence_of :description

validates_length_of :description, :maximum=>40

validates_format_of :private_before_type_cast, :with => /[01]/, :message=>"must be 0 or 1" end

Validating Links between Tables

• the use of belongs_to and validates_associated links the Items table with the item_id field in the Category table.

Documentation: ActiveRecord::Associations::ClassMethods

Validating User Input

validates_presence_of protects ‘NOT NULL fields against missing user input

validates_format_of uses regular expressions to check the format of user input

when a user types input for a numeric field, Rails will always convert it to a number – if all else fails, a zero. If

you want to check that the user has actually typed in a number, then you need to validate the input

_before_type_cast, which lets you access the ‘raw’ input⁵.

validates_inclusion_of checks user input against a range of permitted values

validates_length_of prevents the user entering data which would be truncated when stored⁶.

Documentation: ActiveRecord::Base

More on Views

Sharing Variables between the Templates and the Layout

By now, it is becoming obvious that all my templates will have the same first few lines of code, so it makes sense to move this common code into the layout. Delete all the app\views\layouts\*.rhtml files, and replace with a common application.rhtml.

app\views\layouts\application.rhtml

<%= @flash["notice"] %> </span> <% end %>

<%= @content_for_layout %> </body> </html>

I’ve renamed the public/stylesheets/acaffold.css to ToDo.css for tidiness, and also generally played with colours, table borders, to give a prettier layout. However, returning to Rails, note how the heading variable is shared between the two files, which means that you can have content in the layout dynamically defined by a template:

5 What might seem a more obvious alternative: validates_inclusion_of :done_before_type_cast, :in=>"0".."1", :message=>"must be between 0 and 1" – fails if the input field is left blank

6 You could however combine the two rules for the Description field into one: validates_length_of :description, :within => 1..20

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	belongs_to :category validates_associated :category validates_format_of :done_before_type_cast, :with => /[01]/, :message=>"must be 0 or 1" validates_inclusion_of :priority, :in=>1..5, :message=>"must be between 1 (high) and 5 (low)" validates_presence_of :description validates_length_of :description, :maximum=>40 validates_format_of :private_before_type_cast, :with => /[01]/, :message=>"must be 0 or 1" end *Validating Links between Tables* • the use of belongs_to and validates_associated links the Items table with the item_id field in the Category table.

	Documentation: ActiveRecord::Associations::ClassMethods

	*Validating User Input*

		validates_presence_of protects ‘NOT NULL fields against missing user input validates_format_of uses regular expressions to check the format of user input when a user types input for a numeric field, Rails will always convert it to a number – if all else fails, a zero. If you want to check that the user has actually typed in a number, then you need to validate the input _before_type_cast, which lets you access the ‘raw’ input⁵. validates_inclusion_of checks user input against a range of permitted values validates_length_of prevents the user entering data which would be truncated when stored⁶.





	Documentation: ActiveRecord::Base More on Views Sharing Variables between the Templates and the Layout By now, it is becoming obvious that all my templates will have the same first few lines of code, so it makes sense to move this common code into the layout. Delete all the app\views\layouts\.rhtml files, and replace with a common application.rhtml. app\views\layouts\application.rhtml* <html> <head> <title><%=h @heading %></title> <link href="/stylesheets/ToDo.css" rel="stylesheet" type="text/css" /> </head> <body> <h1><%=h @heading %></h1> <% if @flash["notice"] %> <span class="notice"> <%= @flash["notice"] %> </span> <% end %> <%= @content_for_layout %> </body> </html> I’ve renamed the public/stylesheets/acaffold.css to ToDo.css for tidiness, and also generally played with colours, table borders, to give a prettier layout. However, returning to Rails, note how the heading variable is shared between the two files, which means that you can have content in the layout dynamically defined by a template:

	5 What might seem a more obvious alternative: validates_inclusion_of :done_before_type_cast, :in=>"0".."1", :message=>"must be between 0 and 1" – fails if the input field is left blank 6 You could however combine the two rules for the Description field into one: validates_length_of :description, :within => 1..20

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