Rails - Jul 2007 - Add database field expression (such as Person::Fullname)

I am new to Rails development, having done c++ and other database driven
app development in the past.  Often I would create a database view that
would combine, for example, first and last name values into a
"virtual"
field called FullName.

I don''t see how to use database views with Rails, so I am thinking that
another way to this would be to define a virtual attribute on the
appropriate class to do the same thing (the derived ActiveRecord or
ApplicationController classes?), but I am unclear where and how this
should be declared.

Can anyone point me in the right direction?

Kevin

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On 7/17/07, Kevin Alons
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
>
> I am new to Rails development, having done c++ and other database driven
> app development in the past.  Often I would create a database view that
> would combine, for example, first and last name values into a
"virtual"
> field called FullName.
>
> I don''t see how to use database views with Rails, so I am thinking
that
> another way to this would be to define a virtual attribute on the
> appropriate class to do the same thing (the derived ActiveRecord or
> ApplicationController classes?), but I am unclear where and how this
> should be declared.
>
> Can anyone point me in the right direction?
ActiveRecord docs under "Overwriting default accessors"

http://rails.rubyonrails.org/classes/ActiveRecord/Base.html


-- 
Rick Olson
http://lighthouseapp.com
http://weblog.techno-weenie.net
http://mephistoblog.com

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I''m quite interested in the idea of views,
but I''ve never used them,

i imagine that if you create a view called "people_view",
which is a view on to the people table,

then ActiveRecord will just see this as a normal table?
so

class PersonView < ActiveRecord::Base
   set_table_name :people_view
end

will work.

otherwise,
just do it in ruby

class Person < ActiveRecord::Base
  def full_name
    [first_name, last_name].compact.join(" ")
  end
end

is the normal thing to do.

Kevin Alons wrote:
> I am new to Rails development, having done c++ and other database driven
> app development in the past.  Often I would create a database view that
> would combine, for example, first and last name values into a
"virtual"
> field called FullName.
> 
> I don''t see how to use database views with Rails, so I am thinking
that
> another way to this would be to define a virtual attribute on the
> appropriate class to do the same thing (the derived ActiveRecord or
> ApplicationController classes?), but I am unclear where and how this
> should be declared.
> 
> Can anyone point me in the right direction?
> 
> Kevin

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@Mathew Rudy: Views have nothing to do with the database tables. Views
are just HTML Templates with embedded Ruby to display the data.
so your first idea is totally the wrong direction ;)

However, your 2nd way is the way to go.

On 18 Jul., 13:29, Matthew Rudy
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
> I''m quite interested in the idea of views,
> but I''ve never used them,
>
> i imagine that if you create a view called "people_view",
> which is a view on to the people table,
>
> then ActiveRecord will just see this as a normal table?
> so
>
> class PersonView < ActiveRecord::Base
>    set_table_name :people_view
> end
>
> will work.
>
> otherwise,
> just do it in ruby
>
> class Person < ActiveRecord::Base
>   def full_name
>     [first_name, last_name].compact.join(" ")
>   end
> end
>
> is the normal thing to do.
>
> Kevin Alons wrote:
> > I am new to Rails development, having done c++ and other database
driven
> > app development in the past.  Often I would create a database view
that
> > would combine, for example, first and last name values into a
"virtual"
> > field called FullName.
>
> > I don''t see how to use database views with Rails, so I am
thinking that
> > another way to this would be to define a virtual attribute on the
> > appropriate class to do the same thing (the derived ActiveRecord or
> > ApplicationController classes?), but I am unclear where and how this
> > should be declared.
>
> > Can anyone point me in the right direction?
>
> > Kevin
>
> --
> Posted viahttp://www.ruby-forum.com/.

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Thorsten wrote:
> @Mathew Rudy: Views have nothing to do with the database tables. Views
> are just HTML Templates with embedded Ruby to display the data.
> so your first idea is totally the wrong direction ;)
> 
> However, your 2nd way is the way to go.
> 
> On 18 Jul., 13:29, Matthew Rudy
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
Thorsten the original poster was asking about database views, not html 
templates...

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Sorry, my mistake :-P

On 18 Jul., 15:27, Mikkel Bruun
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
> Thorsten wrote:
> > @Mathew Rudy: Views have nothing to do with the database tables. Views
> > are just HTML Templates with embedded Ruby to display the data.
> > so your first idea is totally the wrong direction ;)
>
> > However, your 2nd way is the way to go.
>
> > On 18 Jul., 13:29, Matthew Rudy
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
>
> Thorsten the original poster was asking about database views, not html
> templates...
>
> --
> Posted viahttp://www.ruby-forum.com/.

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Kevin Alons wrote the following on 18.07.2007 05:58 :
> I am new to Rails development, having done c++ and other database driven
> app development in the past.  Often I would create a database view that
> would combine, for example, first and last name values into a
"virtual"
> field called FullName.
>
> I don''t see how to use database views with Rails, so I am thinking
that
> another way to this would be to define a virtual attribute on the
> appropriate class to do the same thing (the derived ActiveRecord or
> ApplicationController classes?), but I am unclear where and how this
> should be declared.
>
> Can anyone point me in the right direction?
>   
For this particular need, a simple ''full_name'' method in your
model is
probably simpler.
If you need to affect names by full name, you can code a full_name= 
method too.

It''s probably better because:
- much simpler to handle, all your logic is in one place: the model,
- Ruby is more powerful than pure SQL (ie: your full_name will be easier 
to code and extend),
- doing it in the model instead of the DB is more flexible, a model has 
access to code (libraries) you can share easily with other parts of your 
application (most likely other models),
- you don''t have to aggregate data accross rows or join tables to get
at
this data, so doing it in the model can''t be a problem for performance 
(which is not to say that you''ll get better perf using views when joins
are implicated), in fact accessing the DB only once to instanciate the 
model will yield better performance in your case.

Lionel

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I want to say that this is a most helpful forum!  The availability of 
quick, knowledgeable and polite assistance is wonderful!

I have been skeptical about Ruby on Rails as a development language, but 
I may already be won over...  Thanks again for your help (I already have 
more questions!).

-- 
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class Person < AR::Base

  def fullname
    first_name + " " + lastname
  end
end

p = Person.create(:first_name => "Joe", :last_name =>
"Smith")
p.first_name # "Joe"
p.last_name # "Smith"
p.fullname # "Joe Smith"


On 7/17/07, Kevin Alons
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
>
> I am new to Rails development, having done c++ and other database driven
> app development in the past.  Often I would create a database view that
> would combine, for example, first and last name values into a
"virtual"
> field called FullName.
>
> I don''t see how to use database views with Rails, so I am thinking
that
> another way to this would be to define a virtual attribute on the
> appropriate class to do the same thing (the derived ActiveRecord or
> ApplicationController classes?), but I am unclear where and how this
> should be declared.
>
> Can anyone point me in the right direction?
>
> Kevin
>
> --
> Posted via http://www.ruby-forum.com/.
>
> >
>
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I actually prefer

def fullname
  "#{self.first_name} #{self.lastname}"
end

because I don''t get exceptions if someone leaves first_name or
last_name
nil. (That and I like scoping my vars, though that''s not always
necessary.)

On 7/18/07, Chris Hall
<christopher.k.hall-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
>
>
> class Person < AR::Base
>
>   def fullname
>     first_name + " " + lastname
>   end
> end
>
> p = Person.create(:first_name => "Joe", :last_name =>
"Smith")
> p.first_name # "Joe"
> p.last_name # "Smith"
> p.fullname # "Joe Smith"
>
>
> On 7/17/07, Kevin Alons
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:
> >
> > I am new to Rails development, having done c++ and other database
driven
> > app development in the past.  Often I would create a database view
that
> > would combine, for example, first and last name values into a
"virtual"
> > field called FullName.
> >
> > I don''t see how to use database views with Rails, so I am
thinking that
> > another way to this would be to define a virtual attribute on the
> > appropriate class to do the same thing (the derived ActiveRecord or
> > ApplicationController classes?), but I am unclear where and how this
> > should be declared.
> >
> > Can anyone point me in the right direction?
> >
> > Kevin
> >
> > --
> > Posted via http://www.ruby-forum.com/.
> >
> > >
> >
>
> >
>
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Brian Hogan wrote the following on 18.07.2007 16:46 :
> I actually prefer
>
> def fullname
>   "#{self.first_name} #{self.lastname}"
> end
When I said ''extend'' I had one use-case in mind,
here''s a part of one
librairy I coded:

    def fullname
        if firstname.blank? && lastname.blank?
            return _(''Unknown (fill your firstname and lastname
in)'')
        elsif firstname.blank? || lastname.blank?
            # no need for space, one is empty
            return "#{firstname}#{lastname}"
        else
            return "#{firstname} #{lastname}"
        end
    end

Notes:
- _() is from ruby-gettext,
- the .blank? are Rails specific IIRC,
- the return are superfluous, I''m in the process of ditching some of 
them where they don''t help readability.

This would be quite difficult to do in a SQL view...

Lionel.

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I prefer mine;

  def full_name
    [first_name, last_name].compact.join(" ")
  end

as it doesn''t include any unnecessary whitespace in the event that one 
of the names is not defined (or, indeed, both)
Brian Hogan wrote:
> I actually prefer
> 
> def fullname
>   "#{self.first_name} #{self.lastname}"
> end
> 
> because I don''t get exceptions if someone leaves first_name or
last_name
> nil. (That and I like scoping my vars, though that''s not always 
> necessary.)

-- 
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On Jul 18, 2007, at 9:55 , Lionel Bouton wrote:
>
> Brian Hogan wrote the following on 18.07.2007 16:46 :
>> I actually prefer
>>
>> def fullname
>>   "#{self.first_name} #{self.lastname}"
>> end
> - _() is from ruby-gettext,
I''m surprised that in a localized app you''re using attributes
such as
"firstname" and "lastname" :)
> This would be quite difficult to do in a SQL view...
SELECT CASE WHEN firstname = '''' THEN lastname
             WHEN lastname = '''' THEN firstname
             ELSE firstname || '' '' || lastname
        END AS fullname
FROM ...

But I agree it''s easy to handle in the app, and especially for  
localizations.

Michael Glaesemann
grzm seespotcode net



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Michael Glaesemann wrote the following on 19.07.2007 01:59
:
>
>> - _() is from ruby-gettext,
>>     
>
> I''m surprised that in a localized app you''re using
attributes such as
> "firstname" and "lastname" :)
>
>   
I was unaware of cultures where people are named by other means, care to 
point me to them?

Lionel.

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On Jul 18, 2007, at 19:57 , Lionel Bouton wrote:
>
> Michael Glaesemann wrote the following on 19.07.2007 01:59 :
>>
>>> - _() is from ruby-gettext,
>>>
>>
>> I''m surprised that in a localized app you''re using
attributes such as
>> "firstname" and "lastname" :)
>>
>>
>
> I was unaware of cultures where people are named by other means,  
> care to
> point me to them?
Well, for example, Yukihiro Matsumoto would have his name order  
reversed in Japanese. In that case, what is *first* depends on the  
localization.

Michael Glaesemann
grzm seespotcode net



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Michael Glaesemann wrote the following on 19.07.2007 03:21
:
> Well, for example, Yukihiro Matsumoto would have his name order  
> reversed in Japanese. In that case, what is *first* depends on the  
> localization.
>   
Ok. It seems fortunate for me that I''m still far from adressing the 
Japanese market.
The problem is probably a vocabulary one (english isn''t my mother 
tongue) is forname/surname more suited?
It seems a migration is not far away...

Lionel.

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On Jul 18, 2007, at 21:49 , Lionel Bouton wrote:
>
> Michael Glaesemann wrote the following on 19.07.2007 03:21 :
>> Well, for example, Yukihiro Matsumoto would have his name order
>> reversed in Japanese. In that case, what is *first* depends on the
>> localization.
>>
>
> Ok. It seems fortunate for me that I''m still far from adressing
the
> Japanese market.
> The problem is probably a vocabulary one (english isn''t my mother
> tongue) is forname/surname more suited?
Depends on how complicated you want to make it :) I tend to go with  
given name, family name myself, but that still doesn''t cover all the  
variations of names around the world. Though I like surname, the  
"fore" in forename also carries the meaning of in front, which has  
the same issues as first name. But like I said, even these don''t  
cover the full range of human naming schemes.

Michael Glaesemann
grzm seespotcode net



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I love threads like these :)


On 7/18/07, Michael Glaesemann
<grzm-RYEyMNgfJnVLeUupdtUFmg@public.gmane.org>
wrote:
>
>
>
> On Jul 18, 2007, at 21:49 , Lionel Bouton wrote:
>
> >
> > Michael Glaesemann wrote the following on 19.07.2007 03:21 :
> >> Well, for example, Yukihiro Matsumoto would have his name order
> >> reversed in Japanese. In that case, what is *first* depends on the
> >> localization.
> >>
> >
> > Ok. It seems fortunate for me that I''m still far from
adressing the
> > Japanese market.
> > The problem is probably a vocabulary one (english isn''t my
mother
> > tongue) is forname/surname more suited?
>
> Depends on how complicated you want to make it :) I tend to go with
> given name, family name myself, but that still doesn''t cover all
the
> variations of names around the world. Though I like surname, the
> "fore" in forename also carries the meaning of in front, which
has
> the same issues as first name. But like I said, even these don''t
> cover the full range of human naming schemes.
>
> Michael Glaesemann
> grzm seespotcode net
>
>
>
> >
>
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