thr3ads.net - Rails - named_scopes - any reason why you should not alway use a named scope (c.f. a custom method to return limited results) [Jan 2009]

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Greg Hauptmann

2009-Jan-20 01:45 UTC

named_scopes - any reason why you should not alway use a named scope (c.f. a custom method to return limited results)

Hi,

I''ve just discovered the "named_scope" method which seems
great.  I''m
wondering there is any reason why you wouldn''t always use a named scope
(to
get the advantages), over a custom method on your model to return an array
of records?

That is using:

class Shirt < ActiveRecord::Base
    named_scope :red, :conditions => {:color => ''red''}
end

instead of

class Shirt < ActiveRecord::Base
    def red
       Shirt.find_all_by_color(''red'')
    end
end


Comments?



-- 
Greg
http://blog.gregnet.org/

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Robert Walker

2009-Jan-20 02:32 UTC

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Re: named_scopes - any reason why you should not alway use a

Greg Hauptmann wrote:> Hi,
> 
> I''ve just discovered the "named_scope" method which
seems great.  I''m
> wondering there is any reason why you wouldn''t always use a named
scope
> (to
> get the advantages), over a custom method on your model to return an 
> array
> of records?
> 
> That is using:
> 
> class Shirt < ActiveRecord::Base
>     named_scope :red, :conditions => {:color =>
''red''}
> end
> 
> instead of
> 
> class Shirt < ActiveRecord::Base
>     def red
>        Shirt.find_all_by_color(''red'')
>     end
> endWell, this second case is kind of redundant since you are effectively 
creating two methods that do exactly the same thing. The defined method 
"red" and the dynamically created method (via method_missing) 
"find_all_by_color(''red'')"

But, realizing this is a contrived example there are advantages to using 
the named scopes because name scopes can be chained:
large_red_shirts = Shirt.large.red

At least as I understand named_scope.
-- 
Posted via http://www.ruby-forum.com/.

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Greg Hauptmann

2009-Jan-21 11:24 UTC

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Re: named_scopes - any reason why you should not alway use a named scope (c.f. a custom method to return limited results)

(bump)

On Tue, Jan 20, 2009 at 11:45 AM, Greg Hauptmann <
greg.hauptmann.ruby-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Hi,
>
> I''ve just discovered the "named_scope" method which
seems great.  I''m
> wondering there is any reason why you wouldn''t always use a named
scope (to
> get the advantages), over a custom method on your model to return an array
> of records?
>
> That is using:
>
> class Shirt < ActiveRecord::Base
>     named_scope :red, :conditions => {:color =>
''red''}
> end
>
> instead of
>
> class Shirt < ActiveRecord::Base
>     def red
>
>        Shirt.find_all_by_color(''red'')
>     end
> end
>
>
> Comments?
>
>
>
> --
> Greg
> http://blog.gregnet.org/
>
>
>

-- 
Greg
http://blog.gregnet.org/

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Andrew Timberlake

2009-Jan-21 11:42 UTC

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Re: named_scopes - any reason why you should not alway use a named scope (c.f. a custom method to return limited results)

On Tue, Jan 20, 2009 at 3:45 AM, Greg Hauptmann <
greg.hauptmann.ruby-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Hi,
>
> I''ve just discovered the "named_scope" method which
seems great.  I''m
> wondering there is any reason why you wouldn''t always use a named
scope (to
> get the advantages), over a custom method on your model to return an array
> of records?
>
> That is using:
>
> class Shirt < ActiveRecord::Base
>     named_scope :red, :conditions => {:color =>
''red''}
> end
>
> instead of
>
> class Shirt < ActiveRecord::Base
>     def red
>
>        Shirt.find_all_by_color(''red'')
>     end
> end
>
>
> Comments?
>
>
>
> --
> Greg
> http://blog.gregnet.org/
>
>
>
> >
>The only reason to use a custom method instead of a named_scope is when
you''re doing more than querying the db or there''s something
named_scopes
can''t handle.

-- 
Andrew Timberlake
http://ramblingsonrails.com
http://www.linkedin.com/in/andrewtimberlake

"I have never let my schooling interfere with my education" - Mark
Twain

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Greg Hauptmann

2009-Jan-21 20:15 UTC

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Re: named_scopes - any reason why you should not alway use a named scope (c.f. a custom method to return limited results)

ok - so if you had the time, updating all your custom finder methods to
named_scope would give you more flexibility then.  I was just wanting to
check if there were any negatives or gotchas to named_scope''s

On Wed, Jan 21, 2009 at 9:42 PM, Andrew Timberlake <
andrew-642hCh26+Dt3UeSHeRwt+FaTQe2KTcn/@public.gmane.org> wrote:
> On Tue, Jan 20, 2009 at 3:45 AM, Greg Hauptmann <
> greg.hauptmann.ruby-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
>> Hi,
>>
>> I''ve just discovered the "named_scope" method which
seems great.  I''m
>> wondering there is any reason why you wouldn''t always use a
named scope (to
>> get the advantages), over a custom method on your model to return an
array
>> of records?
>>
>> That is using:
>>
>> class Shirt < ActiveRecord::Base
>>     named_scope :red, :conditions => {:color =>
''red''}
>> end
>>
>> instead of
>>
>> class Shirt < ActiveRecord::Base
>>     def red
>>
>>
>>        Shirt.find_all_by_color(''red'')
>>     end
>> end
>>
>>
>> Comments?
>>
>>
>>
>> --
>> Greg
>> http://blog.gregnet.org/
>>
>>
>>
>>
>>
> The only reason to use a custom method instead of a named_scope is when
> you''re doing more than querying the db or there''s
something named_scopes
> can''t handle.
>
> --
> Andrew Timberlake
> http://ramblingsonrails.com
> http://www.linkedin.com/in/andrewtimberlake
>
> "I have never let my schooling interfere with my education" -
Mark Twain
>
> >
>

-- 
Greg
http://blog.gregnet.org/

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Andrew Timberlake

2009-Jan-22 09:01 UTC

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Re: named_scopes - any reason why you should not alway use a named scope (c.f. a custom method to return limited results)

On Wed, Jan 21, 2009 at 10:15 PM, Greg Hauptmann <
greg.hauptmann.ruby-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> ok - so if you had the time, updating all your custom finder methods to
> named_scope would give you more flexibility then.  I was just wanting to
> check if there were any negatives or gotchas to named_scope''s
>
>It would definitely give you more flexibility because of the ability to
chain together named_scopes.

-- 
Andrew Timberlake
http://ramblingsonrails.com
http://www.linkedin.com/in/andrewtimberlake

"I have never let my schooling interfere with my education" - Mark
Twain

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Rails - Jan 2009 - named_scopes - any reason why you should not alway use a named scope (c.f. a custom method to return limited results)

named_scopes - any reason why you should not alway use a named scope (c.f. a custom method to return limited results)

Re: named_scopes - any reason why you should not alway use a

Re: named_scopes - any reason why you should not alway use a named scope (c.f. a custom method to return limited results)

Re: named_scopes - any reason why you should not alway use a named scope (c.f. a custom method to return limited results)

Re: named_scopes - any reason why you should not alway use a named scope (c.f. a custom method to return limited results)

Re: named_scopes - any reason why you should not alway use a named scope (c.f. a custom method to return limited results)