opensoul.org - Making #composed_of more useful Comments

Comment on 'Making #composed_of more useful' by Ole Begemann

2007-12-14T14:56:26Z

Congratulations on the accepted patch, Brandon. I’ve just begun using it in my project together with the Money gem, too.

class Project < ActiveRecord::Base
  composed_of :budget, :class_name => "Money", :mapping => %w(budget cents), :allow_nil => true do |amount|
    amount.to_money
  end
end

The backend part works great but I seem to have one problem with displaying the form field in an edit form:

<%= f.text_field "budget" %>

This displays the cents value in the input field (i.e. “24099”) while I obviously would like it to display it in EUR instead (“240.99”). When I then submit the form without changing anything, the “24099” gets converted to a Money object representing 24099 EUR.

Looking at Rails’s form_helper.rb, the reason seems to be that Rails calls @project.budget_before_type_cast to construct the display value for the input field and sure enough, this yields the cents value.

Have you experienced this problem? Or does it work differently for you? Overwriting budget_before_type_cast should do the trick, but I’m curious why nobody else seems to have this problem. I’m on Rails 2.0.1.

Comment on 'Making #composed_of more useful' by Brandon

2007-10-24T04:05:51Z

The patch finally got accepted.

Comment on 'Making #composed_of more useful' by Chris Cruft

2007-10-09T13:00:07Z

Brandon, I’ve been using your patch for some time and nursing it along with an update lately (update available on dev.rubyonrails.org). I’m tired of this being a patch since it fixes an egregious problem with nil values as well.

Any chance you can shake the trees by posting to the Rails core Google Group? I’ll pile on and back you up, and I know Ian White will as well (he and I worked on an earlier patch that fixed that nil problem).

-Chris

Comment on 'Making #composed_of more useful' by Dave Bryand

2007-06-26T18:21:53Z

Sweet—I don’t think that will be an issue in my case.

Thanks!

Comment on 'Making #composed_of more useful' by Brandon

2007-06-22T06:42:05Z

Dave,

The only issue I can think of is if you want the composed_of object to use the same name as an attribute. For example, if you have a field called balance that you want to be replaced by the composed_of.

Other than that, I think it’s a good idea.

Comment on 'Making #composed_of more useful' by Dave Bryand

2007-06-21T16:31:29Z

Thanks for this—it was a big help.

What I’d like to be able to do is to pass the value from an instance method that I create into the mapping of “composed_of”.

In both the Rails source and your plugin, the value that gets passed from the model containing the composed_of call into the other model has to be in @attributes.

I made it work by simply changing the read_method method slightly. Instead of reading the attribute, I just call send and pass it the first element of the the mapping.

read_attribute(pair.first)

send(pair.first)


        def reader_method(name, class_name, mapping, allow_nil)
          module_eval do
            define_method(name) do |*args|
              force_reload = args.first || false
              if (instance_variable_get("@#{name}").nil? || force_reload) && (!allow_nil || mapping.any? {|pair| !read_attribute(pair.first).nil? })
                # instance_variable_set("@#{name}", class_name.constantize.new(*mapping.collect {|pair| read_attribute(pair.first)}))
                instance_variable_set("@#{name}", class_name.constantize.new( *mapping.collect do |pair| send(pair.first) end ))
              end
              return instance_variable_get("@#{name}")
            end
          end
        end

Can you think of any negative effects that this might have? Is there a better way to do it?

Thanks!

Comment on 'Making #composed_of more useful' by jerry rirchardson

2007-01-12T15:54:08Z

i had been banging my head on my desk for an hour or so, but you came to my rescue. Hail the liberator! Hail Brandon! I hope your patch gets into rails.

Comment on 'Making #composed_of more useful' by Brandon

2006-12-08T19:35:32Z

jake:

I’m not sure that I get what you mean, could you give an example?

Comment on 'Making #composed_of more useful' by jake

2006-12-04T19:39:19Z

Thanks for this article. I am currently facing a puzzle: is it possible to create ActiveRecord aggregations for objects whose attributes include other objects? If I don’t need to be able to access the attributes of the sub-object, can I just declare the object column as type :binary and be done with it? The Rails docs are mum on this so any hints would be greatly appreciated!