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linus1412

2006-Dec-01 22:45 UTC

Overriding default ActiveRecord getter and setter

Hi,

I have two ActiveRecord classes, Player and User.  Both underlying
tables have a column called email.

class User < ActiveRecord::Base
end

class Player < ActiveRecord::Base
  belongs_to :user
end

If the player instance''s user attribute is not nil I want any reference
to player.email get or set player.user.email - so I tried this...

class Player < ActiveRecord::Base
  belongs_to :user
  def email
    return user.email if !(user.nil? || user.empty?)
  end
end

... but it doesn''t work.  When I retreive a relevant player object and
try player.email I still get the email address from the player rather
than the user.

Any ideas where I am going wrong?

Martin


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Zack Chandler

2006-Dec-01 23:18 UTC

head link

Re: Overriding default ActiveRecord getter and setter

On 12/1/06, linus1412
<linus141275-PkbjNfxxIARBDgjK7y7TUQ@public.gmane.org>
wrote:>
> Hi,
>
> I have two ActiveRecord classes, Player and User.  Both underlying
> tables have a column called email.
>
> class User < ActiveRecord::Base
> end
>
> class Player < ActiveRecord::Base
>   belongs_to :user
> end
>
> If the player instance''s user attribute is not nil I want any
reference
> to player.email get or set player.user.email - so I tried this...
>
> class Player < ActiveRecord::Base
>   belongs_to :user
>   def email
>     return user.email if !(user.nil? || user.empty?)
>   end
> end
>
> ... but it doesn''t work.  When I retreive a relevant player object
and
> try player.email I still get the email address from the player rather
> than the user.
>
> Any ideas where I am going wrong?
>
> Martin
>
>
> >
>
Martin,

Try this:

def email
  user ? user.email : self[:email]
end

--
Zack Chandler
http://depixelate.com
http://trackplace.com

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linus1412

2006-Dec-01 23:50 UTC

head link

Re: Overriding default ActiveRecord getter and setter

Zack,

I added...

  def email
	user ? user.email : self[:email]
  end

  def email=(email)
    (user ? user : self).email = email
  end

This still doesn''t work, it still brings back the player.email value.

Strangely it does work in console.

Martin

On Dec 1, 11:18 pm, "Zack Chandler"
<zackchand...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> On 12/1/06, linus1412
<linus141...-PkbjNfxxIARBDgjK7y7TUQ@public.gmane.org> wrote:
>
>
>
>
>
> > Hi,
>
> > I have two ActiveRecord classes, Player and User.  Both underlying
> > tables have a column called email.
>
> > class User < ActiveRecord::Base
> > end
>
> > class Player < ActiveRecord::Base
> >   belongs_to :user
> > end
>
> > If the player instance''s user attribute is not nil I want any
reference
> > to player.email get or set player.user.email - so I tried this...
>
> > class Player < ActiveRecord::Base
> >   belongs_to :user
> >   def email
> >     return user.email if !(user.nil? || user.empty?)
> >   end
> > end
>
> > ... but it doesn''t work.  When I retreive a relevant player
object and
> > try player.email I still get the email address from the player rather
> > than the user.
>
> > Any ideas where I am going wrong?
>
> > MartinMartin,
>
> Try this:
>
> def email
>   user ? user.email : self[:email]
> end
> 
> --
> Zack Chandlerhttp://depixelate.comhttp://trackplace.com

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linus1412

2006-Dec-02 00:32 UTC

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Re: Overriding default ActiveRecord getter and setter

I can reproduce the same behaviour in console by doing

p = Player.find 4
p.email   => "user-email-gJ1G9MGqaQg@public.gmane.org"           #
what i want
p[:email] => "player-email-gJ1G9MGqaQg@public.gmane.org"      # not
what i want

So are forms populated using second approach?

If so this seems to negate accessor overloading as far as form handling
is concerned.

Martin


On Dec 1, 11:50 pm, "linus1412"
<linus141...-PkbjNfxxIARBDgjK7y7TUQ@public.gmane.org>
wrote:> Zack,
>
> I added...
>
>   def email
>         user ? user.email : self[:email]
>   end
>
>   def email=(email)
>     (user ? user : self).email = email
>   end
>
> This still doesn''t work, it still brings back the player.email
value.
>
> Strangely it does work in console.
>
> Martin
>
> On Dec 1, 11:18 pm, "Zack Chandler"
<zackchand...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> > On 12/1/06, linus1412
<linus141...-PkbjNfxxIARBDgjK7y7TUQ@public.gmane.org> wrote:
>
> > > Hi,
>
> > > I have two ActiveRecord classes, Player and User.  Both
underlying
> > > tables have a column called email.
>
> > > class User < ActiveRecord::Base
> > > end
>
> > > class Player < ActiveRecord::Base
> > >   belongs_to :user
> > > end
>
> > > If the player instance''s user attribute is not nil I
want any reference
> > > to player.email get or set player.user.email - so I tried this...
>
> > > class Player < ActiveRecord::Base
> > >   belongs_to :user
> > >   def email
> > >     return user.email if !(user.nil? || user.empty?)
> > >   end
> > > end
>
> > > ... but it doesn''t work.  When I retreive a relevant
player object and
> > > try player.email I still get the email address from the player
rather
> > > than the user.
>
> > > Any ideas where I am going wrong?
>
> > > MartinMartin,
>
> > Try this:
>
> > def email
> >   user ? user.email : self[:email]
> > end
> 
> > --
> > Zack Chandlerhttp://depixelate.comhttp://trackplace.com

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Zack Chandler

2006-Dec-02 06:24 UTC

head link

Re: Overriding default ActiveRecord getter and setter

On 12/1/06, linus1412
<linus141275-PkbjNfxxIARBDgjK7y7TUQ@public.gmane.org>
wrote:>
> I can reproduce the same behaviour in console by doing
>
> p = Player.find 4
> p.email   => "user-email-gJ1G9MGqaQg@public.gmane.org"        
# what i want
> p[:email] => "player-email-gJ1G9MGqaQg@public.gmane.org"     
# not what i want
>
> So are forms populated using second approach?
>
> If so this seems to negate accessor overloading as far as form handling
> is concerned.
>
> Martin
>
>
> On Dec 1, 11:50 pm, "linus1412"
<linus141...-PkbjNfxxIARBDgjK7y7TUQ@public.gmane.org> wrote:
> > Zack,
> >
> > I added...
> >
> >   def email
> >         user ? user.email : self[:email]
> >   end
> >
> >   def email=(email)
> >     (user ? user : self).email = email
> >   end
> >
> > This still doesn''t work, it still brings back the
player.email value.
> >
> > Strangely it does work in console.
> >
> > Martin
> >
> > On Dec 1, 11:18 pm, "Zack Chandler"
<zackchand...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> >
> > > On 12/1/06, linus1412
<linus141...-PkbjNfxxIARBDgjK7y7TUQ@public.gmane.org> wrote:
> >
> > > > Hi,
> >
> > > > I have two ActiveRecord classes, Player and User.  Both
underlying
> > > > tables have a column called email.
> >
> > > > class User < ActiveRecord::Base
> > > > end
> >
> > > > class Player < ActiveRecord::Base
> > > >   belongs_to :user
> > > > end
> >
> > > > If the player instance''s user attribute is not nil
I want any reference
> > > > to player.email get or set player.user.email - so I tried
this...
> >
> > > > class Player < ActiveRecord::Base
> > > >   belongs_to :user
> > > >   def email
> > > >     return user.email if !(user.nil? || user.empty?)
> > > >   end
> > > > end
> >
> > > > ... but it doesn''t work.  When I retreive a
relevant player object and
> > > > try player.email I still get the email address from the
player rather
> > > > than the user.
> >
> > > > Any ideas where I am going wrong?
> >
> > > > MartinMartin,
> >
> > > Try this:
> >
> > > def email
> > >   user ? user.email : self[:email]
> > > end
> >
> > > --
> > > Zack Chandlerhttp://depixelate.comhttp://trackplace.com
>
>
> >
>
Martin,
> p.email   => "user-email-gJ1G9MGqaQg@public.gmane.org"        
# what i want
This is good.
> p[:email] => "player-email-gJ1G9MGqaQg@public.gmane.org"     
# not what i want
This is not good because it bypasses the accessor that you just wrote.
 The reason is ActiveRecord::Base overrides [] like this:

      def [](attr_name)
        read_attribute(attr_name)
      end

... so it reads the actual column data.  Use the first approach.

Hope this helps.

--
Zack Chandler
http://depixelate.com
http://trackplace.com

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linus1412

2006-Dec-02 23:11 UTC

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Re: Overriding default ActiveRecord getter and setter

Zack,

In console I have the choice to use p.email, but when my form displays
it is still showing the data from the player object, bypassing my
overridden method.

I assume that <%= text_field ''player'',
''email''  %> must effectively
still call read_attribute(attr_name) rather than use the accessor.

Martin


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linus1412

2006-Dec-04 00:27 UTC

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Re: Overriding default ActiveRecord getter and setter

I think I may have found an answer to this, but it doesn''t seem write.

If I override the player_before_type_cast and player_before_type_castmethods it
works, as this is what the form calls to get the values to
display?

This works, but its it ''right''?

Martin


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Maxim Kulkin

2006-Dec-04 08:10 UTC

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Re: Overriding default ActiveRecord getter and setter

On 4 December 2006 03:27, linus1412 wrote:> I think I may have found an answer to this, but it doesn''t seem
write.
>
> If I override the player_before_type_cast and player_before_type_cast>
methods it works, as this is what the form calls to get the values to
> display?
>
> This works, but its it ''right''?The problem is that text_field uses *_before_type_cast accessors to get data.
I see two solutions:
  1. overriding *_before_type_cast accessor (as you described)
  2. adding virtual field (that has no underlying column). E.g. in your case 
this could be done like this:

  class Player
    def user_or_player_email
      return user.email if user
      self.email
    end
    def user_or_player_email=(value)
      self.email = value
    end
  end

The trick here is that text_field will use plain value (not _before_type_cast 
variant) if attribute doesn''t support _before_type_cast accessor.

Although, I would prefer using second variant.

You could rename players.email column to something like "custom_email"
or "player_email" and use "email" as the name of virtual
attribute.

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Frederick Cheung

2006-Dec-04 10:44 UTC

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Re: Overriding default ActiveRecord getter and setter

The other thing is that the various accessor methods are added 
dynamically when they are first called, which probably means they 
overwrite the email method you have defined.

Fred

-- 
Posted via http://www.ruby-forum.com/.

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Maxim Kulkin

2006-Dec-04 11:10 UTC

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Re: Overriding default ActiveRecord getter and setter

On 4 December 2006 13:44, Frederick Cheung wrote:> The other thing is that the various accessor methods are added
> dynamically when they are first called, which probably means they
> overwrite the email method you have defined.
No, dynamically generated accessors for DB columns do not overwrite existing 
accessors. Dynamic accessor don''t get generated if there is method with
the
same name already.

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Rails - Dec 2006 - Overriding default ActiveRecord getter and setter

Overriding default ActiveRecord getter and setter

Re: Overriding default ActiveRecord getter and setter

Re: Overriding default ActiveRecord getter and setter

Re: Overriding default ActiveRecord getter and setter

Re: Overriding default ActiveRecord getter and setter

Re: Overriding default ActiveRecord getter and setter

Re: Overriding default ActiveRecord getter and setter

Re: Overriding default ActiveRecord getter and setter

Re: Overriding default ActiveRecord getter and setter

Re: Overriding default ActiveRecord getter and setter