Here is one my brother showed me the other day that I was not aware of. More RTFM and less Cowboy Coding.. I know, I know.. its just my nature. So here is the use case: You have a collection of objects that you want rendered in a partial. The way I used to do it is like this:

#controller code
@widgets = Widget.all

# view code
<%= render :partial=>"widgets/widget" %>

#partial code
<% @widgets.each do |widget| %>
  This widget is named <%=widget.name %> 

<% end %>

Now that is kinda ugly doing the iteration in the partial like that. Now for a cleaner way. You pass the @widgets to the partial with the :collection hash.

#controller code
@widgets = Widget.all

# view code
<%= render :partial=>"widgets/widget", :collection=>@widgets %>

#partial code
  This widget is named <%=widget.name %> 

This code will execute the partial multiple times.. once for each widget in the widget collection. That looks damn pretty. One caveat, though.. In the partial, the name of the local variable needs to be the same as the name of the partial. So if you have widgets/some_widget, the code would look like this:

  This widget is named <%=some_widget.name %> 

If you want to use another variable name you just add the :as hash, like this:

<%= render :partial=>"widgets/some_widget", :collection=>@widgets, :as=>:widget %>

Then you can use widget as the local variable name instead of some_widget. Got it? Good.

Tags: ruby on rails

Lets say you have a widget model in Ruby on Rails.  Your database table contains a field called “name”.  Let’s say you want to add something to this field in your model.  You need a specialized def in order to do this.. you need to use write_attribute and read_attribute methods.

Here is an example where I override the Rails ActiveRecord model attribute setter. This will append a test string onto the name:

class Widget < ActiveRecord::Base
  def name=(name)
    write_attribute(:name,"#{name} - test")
  end
end

You can also do this with the read_attribute method and it works the opposite way… instead of operating on the setter, you operate on the getter.

Tags: ruby on rails

I thought this was pretty cool and a little more elegant than using a string, which I have been doing before I saw this. In SQL you can do a command like so:

SELECT * FROM widgets WHERE id IN (1,2,3,4,5);

I was doing this before:

Widget.find(:all,:conditions=>"id in (1,2,3,4,5)")

Instead of doing this you can use an array instead of a string:

Widget.find(:all,:conditions=> {:id => [1,2,3,4,5])

That looks better. Guess I should RTFM next time.

Tags: ruby on rails