Forum: Ruby on Rails problem with named_scope and test-spec?

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Tom M (Guest)
on 2009-01-15 18:23
(Received via mailing list)
I may be overlooking something, but it seems to me that it is a
problem if with this code...

Class Blog < ActiveRecord::Base
  named_scope :unseen, :conditions => "displayed IS NULL"
end

this test fails...

it "should give a list of unseen entries" do
  Blog.expects :unseen
  b = Blog.new
  b.unseen
end

given that the docs say about named_scope:

"Adds a class method for retrieving and querying objects. A scope
represents a narrowing of a database query, such as :conditions =>
{:color => :red}, :select => ‘shirts.*’, :include
=> :washing_instructions.
  class Shirt < ActiveRecord::Base
    named_scope :red, :conditions => {:color => 'red'}
    named_scope :dry_clean_only, :joins
=> :washing_instructions, :conditions =>
['washing_instructions.dry_clean_only = ?', true]
  end
The above calls to named_scope define class methods Shirt.red and
Shirt.dry_clean_only. Shirt.red, in effect, represents the query
Shirt.find(:all, :conditions => {:color => ‘red’})."

Am I missing something?

Thanks,
Tom
Patrick D. (Guest)
on 2009-01-15 18:53
(Received via mailing list)
On Thu, Jan 15, 2009 at 11:21 AM, Tom M <removed_email_address@domain.invalid>
wrote:

> it "should give a list of unseen entries" do
>  Blog.expects :unseen
>  b = Blog.new
>  b.unseen
> end
>
> I don't know if this will help or not, but the little I've used named
scopes, I've used them as class methods, not as instance methods, i.e.
Blog.unseen not b.unseen.

--wpd
Tom M (Guest)
on 2009-01-15 20:30
(Received via mailing list)
Patrick,

Thanks... I checked again and the example I posted was a bit off of my
real example, which uses associations and scopes.  According to the
docs:

All \scopes are available as class methods on the ActiveRecord::Base
descendent upon which the \scopes were defined. But they are also
available to has_many associations. If,
  class Person < ActiveRecord::Base
    has_many :shirts
  end
then elton.shirts.red.dry_clean_only will return all of Elton’s red,
dry clean only shirts.


 So a better example would be:
b = Blog.first
b.entries.unseen

I guess in this case, the method :unseen is bound to the set returned
via the association, and not the class itself?

Tom
Patrick D. (Guest)
on 2009-01-15 20:49
(Received via mailing list)
On Thu, Jan 15, 2009 at 1:29 PM, Tom M <removed_email_address@domain.invalid> 
wrote:

>  class Person < ActiveRecord::Base
> I guess in this case, the method :unseen is bound to the set returned
> via the association, and not the class itself?
>
> I'm not too sure what you mean by that.  As I've used named scopes, I have
been confused by thinking that entries.unseen was an array such as is
returned by #find, when, it seems, it is a piece of RoR magic that looks
more like the model.  I wonder if b.entries.unseen.all or
b.entries.unseen.first might do what you need it to.

(Between you and me, I'm hoping that somebody who knows what (s)he is
talking about chimes in here pretty soon, as this is already out of my
depth. :-))

--wpd
Tom M (Guest)
on 2009-01-16 05:17
(Received via mailing list)
Well, I guess I/we are on our own.  I'll try to dig a bit deeper and
see if I can find out just what's going on w/ those associations.
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