Screencasts skill (II)

Dynamic Select Menus
可以用生個javascript stylesheets controller 來動態生js , css
在利用content_for 動態 include
<br /># application_helper.rb<br />def javascript(*files)<br /> content_for(:head) { javascript_include_tag(*files) }<br />end<br /><br />def stylesheet(*files)<br /> content_for(:head) { stylesheet_link_tag(*files) }<br />end<br />

Formatting Time
<br /># config/environment.rb<br />Time::DATE_FORMATS[:due_time] = "due on %B %d at %I:%M %p"<br />

Performing Calculations on Models
<br />Task.sum(:priority)<br />Task.sum(:priority, :conditions => 'complete=0')<br />Task.maximum(:priority)<br />Task.minimum(:priority)<br />Task.average(:priority)<br />p = Project.find(:first)<br />p.tasks.sum(:priority)<br />p.tasks.sum(:priority, :conditions => 'complete=0')<br />

Optimistic Locking
<br />rescue ActiveRecord::StaleObjectError<br /> @product.reload<br /> render :action => 'conflict'<br /><br /><br /><!-- _form.rhtml --><br /><%= f.hidden_field :lock_version %><br />