i got it.
reference this url:
http://refactormycode.com/codes/209-rails-has_many-count
sample code:
class User
has_many :messages do
def by_type(type, options={})
options[:count_only] ||= false
messages = find(:all, :conditions => [ 'type = ?', type ])
options[:count_only] ? messages.size : messages
end
end
end
OPTION 1: without helper in view
<h1>Messages:</h1>
<ul>
<li>Industry Expert: <%= current_user.messages.by_type('Industry
Expert', :count_only => true) -%></li>
<li>Media: <%= current_user.messages.by_type('Media',
:count_only => true) -%></li>
<li>PR: <%= current_user.messages.by_type('PR',
:count_only => true) -%></li>
</ul>
2009/12/2 tommy xiao <[email protected]>
> i think use named_scope is not elegant way. use class method? no idea.you
> can give me your sample proj.i can test this way.
>
> 2009/12/2 Jeff Blasius <[email protected]>
>
> How would I write a named_scope that checks if the parent has at least
>> one associated child?
>>
>> For example,
>> class Post < ActiveRecord::Base
>> has many :comments
>>
>> named_scope :commented_on, :conditions => "comments.count > 0"
>>
>>
>> class Comment < ActiveRecord::Base
>> belongs_to :post
>>
>>
>>
>> Thanks,
>> jeff
>>
>> --
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>>
>>
>
>
> --
> tommy xiao
> E-mail: xiaods(AT)gmail.com
>
--
tommy xiao
E-mail: xiaods(AT)gmail.com
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