Session 5 of the URUG Free Ruby on Rails workshop. This is the second tutorial session.

1. Ruby on Rails
Workshop
Brad Midgley

2. About me
• U of U grad
• U of Colorado at Colorado Springs
• Worked in Linux--Turbolinux
• Worked in Java--U of U
• Rails/iPhone--Surgeworks

3. This is not a toy

4. Neither is Rails
• Programmers choose and enjoy it
• Huge collaboration benefit
• Open-source, freedom in license
• Inspiring other frameworks/languages

5. More Data Handling
• Using git
• Filtering at the model
• Sorting, driven by UI
• Filtering at the UI, search

6. Workshop up
• Project up-to-date
• Some data, user account
• Using/watching server log
• Launching console, interacting with app

7. Named scopes
• Spoiler?
• Enhancing the model
• Specify a subset of all rows
• Named scopes can be efficiently combined

8. Simple example
named_scope :family_friendly, :conditions => “rating in (‘G’, ‘PG’)”
Movie.family_friendly
Movie.family_friendly.all(:order => :genre)
Movie.family_friendly.all(:conditions => {:genre => 'Comedy'})

9. Create your own
• Think of a subset of users or movies
• Implement in app/models/*.rb
• Test using console
• Combine filters

10. Click-to-sort columns
• Very common to use ajax
• Often using a plugin
• A simple approach to start with

11. Non-ajax colsort
• http://garbageburrito.com/blog/entry/447/
rails-super-cool-simple-column-sorting
• View renders an action with parameters to
initiate sort
• Model watches for the parameters

12. Limitations?
• Doesn’t indicate sort order
• We’re not handling paging, will complicate it
• Let’s fix the first one

13. Sort order icon
• Poach up and down triangles
• No triangle if not sorting on this column
• Appropriate triangle for sort order
• Where does this code go?

14. Search
• Search on title for now
• UI component
• Server filter component

15. A special form
• Normally forms post
• Search has no side effects
• Search should be bookmarkable
• Make it a get, re-use the action we are on

16. Form front
<% form_tag(movies_path, :method => "get") do %>
<%= text_field_tag(:s) %>
<%= submit_tag("Search", :name => nil) %>
<% end %>

17. Form handler
• Watch params[:s]
• Try to keep existing code from today
• Remember we are passing a hash
• Implement this in controllers/
movie_controller.rb
• Modify the result set in @movies
• GO

18. Hints

19. Hints
• :conditions => ['title like ?', "%#{params[:s]}%"]

20. Hints
• :conditions => ['title like ?', "%#{params[:s]}%"]
• overlay with :order => ...

21. Hints
• :conditions => ['title like ?', "%#{params[:s]}%"]
• overlay with :order => ...
• Construct a hash with only the :order and
optionally add the :conditions => ...