Rails - Dec 2012 - why do I have to refer to my attr_accessible as self.varname?

I posted a previous message about overriding initialize... because I was 
having issues setting some of the parameters.  I have a Page model that has:

attr_accessible :url, :title, :doc, :domain

and it''s called via:

Page.new(:url => ''http://www.yahoo.com'')

Since I''m only passing in the url to new, I needed to set the other 
parameters.  I was trying to do this via an after_initialize callback which 
wasn''t working so tried overriding initialize... still not working.

What I found out was that in my after_initialize, I was referring to title 
as @title which is why it was not working.  I switched it to self.title and 
it works fine.

My question is - why?

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To view this discussion on the web visit
https://groups.google.com/d/msg/rubyonrails-talk/-/-ncNakybQ-cJ.
For more options, visit https://groups.google.com/groups/opt_out.

On Dec 21, 2012, at 12:37 PM, Dan Brooking wrote:
> I posted a previous message about overriding initialize... because I was
having issues setting some of the parameters.  I have a Page model that has:
> 
> attr_accessible :url, :title, :doc, :domain
> 
> and it''s called via:
> 
> Page.new(:url => ''http://www.yahoo.com'')
> 
> Since I''m only passing in the url to new, I needed to set the
other parameters.  I was trying to do this via an after_initialize callback
which wasn''t working so tried overriding initialize... still not
working.
> 
> What I found out was that in my after_initialize, I was referring to title
as @title which is why it was not working.  I switched it to self.title and it
works fine.
> 
> My question is - why?
@title is an instance variable. Until you set it, it doesn''t exist.
Having a method on the model called title (or an accessor, or some other Rails
magick) does not instantiate that method''s return until and unless you
ask for it by calling the method. Calling self.method_name just makes it clear
which same-named method you really mean. Self is implied much of the time, but
when you have all the many method_missing options available, it might not be the
first one such that gets called.

Walter
> 
> -- 
> You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
> To view this discussion on the web visit
https://groups.google.com/d/msg/rubyonrails-talk/-/-ncNakybQ-cJ.
> For more options, visit https://groups.google.com/groups/opt_out.
>  
>  
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.

So is the way I''m doing it right?  Or just a way I happened to hack it
to
work?

The way my code was looking was basically:

Page.new(:url => ''http://www.yahoo.com'')

class Page < ActiveRecord::Base
  attr_accessible :url, :title

  after_initialize :parse_page_params

  def parse_page_params
    @title = "test"
  end

and this wasn''t working...  I understand what you said above about the
instance variables, methods, initializing, etc.. but still a little unclear
about why that code doesn''t work as I''m setting it.  Is it
because Rails
uses the method name of title which hasn''t been initailized in my
assignment above?




On Fri, Dec 21, 2012 at 12:43 PM, Walter Lee Davis
<waltd-HQgmohHLjDZWk0Htik3J/w@public.gmane.org>wrote:
>
> On Dec 21, 2012, at 12:37 PM, Dan Brooking wrote:
>
> > I posted a previous message about overriding initialize... because I
was
> having issues setting some of the parameters.  I have a Page model that
has:
> >
> > attr_accessible :url, :title, :doc, :domain
> >
> > and it''s called via:
> >
> > Page.new(:url => ''http://www.yahoo.com'')
> >
> > Since I''m only passing in the url to new, I needed to set the
other
> parameters.  I was trying to do this via an after_initialize callback which
> wasn''t working so tried overriding initialize... still not
working.
> >
> > What I found out was that in my after_initialize, I was referring to
> title as @title which is why it was not working.  I switched it to
> self.title and it works fine.
> >
> > My question is - why?
>
> @title is an instance variable. Until you set it, it doesn''t
exist. Having
> a method on the model called title (or an accessor, or some other Rails
> magick) does not instantiate that method''s return until and unless
you ask
> for it by calling the method. Calling self.method_name just makes it clear
> which same-named method you really mean. Self is implied much of the time,
> but when you have all the many method_missing options available, it might
> not be the first one such that gets called.
>
> Walter
>
> >
> > --
> > You received this message because you are subscribed to the Google
> Groups "Ruby on Rails: Talk" group.
> > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > To unsubscribe from this group, send email to
>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > To view this discussion on the web visit
> https://groups.google.com/d/msg/rubyonrails-talk/-/-ncNakybQ-cJ.
> > For more options, visit https://groups.google.com/groups/opt_out.
> >
> >
>
> --
> You received this message because you are subscribed to the Google Groups
> "Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> For more options, visit https://groups.google.com/groups/opt_out.
>
>
>
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit https://groups.google.com/groups/opt_out.

On Dec 21, 2012, at 1:12 PM, Dan Brooking wrote:
> So is the way I''m doing it right?  Or just a way I happened to
hack it to work?
> 
> The way my code was looking was basically:
> 
> Page.new(:url => ''http://www.yahoo.com'')
> 
> class Page < ActiveRecord::Base
>   attr_accessible :url, :title
> 
>   after_initialize :parse_page_params
> 
>   def parse_page_params
>     @title = "test"
>   end
> 
Have a look at the documentation for after_initialize -- it runs once, after
Rails itself is fully initialized. Is that the point at which you mean to
instantiate the instance variable @title? Which instance of its class would it
attach to? Can you please describe what you intend to do with @title -- where
it''s going to be used?

Walter
> and this wasn''t working...  I understand what you said above about
the instance variables, methods, initializing, etc.. but still a little unclear
about why that code doesn''t work as I''m setting it.  Is it
because Rails uses the method name of title which hasn''t been
initailized in my assignment above?
> 
> 
> 
> 
> On Fri, Dec 21, 2012 at 12:43 PM, Walter Lee Davis
<waltd-HQgmohHLjDZWk0Htik3J/w@public.gmane.org> wrote:
> 
> On Dec 21, 2012, at 12:37 PM, Dan Brooking wrote:
> 
> > I posted a previous message about overriding initialize... because I
was having issues setting some of the parameters.  I have a Page model that has:
> >
> > attr_accessible :url, :title, :doc, :domain
> >
> > and it''s called via:
> >
> > Page.new(:url => ''http://www.yahoo.com'')
> >
> > Since I''m only passing in the url to new, I needed to set the
other parameters.  I was trying to do this via an after_initialize callback
which wasn''t working so tried overriding initialize... still not
working.
> >
> > What I found out was that in my after_initialize, I was referring to
title as @title which is why it was not working.  I switched it to self.title
and it works fine.
> >
> > My question is - why?
> 
> @title is an instance variable. Until you set it, it doesn''t
exist. Having a method on the model called title (or an accessor, or some other
Rails magick) does not instantiate that method''s return until and
unless you ask for it by calling the method. Calling self.method_name just makes
it clear which same-named method you really mean. Self is implied much of the
time, but when you have all the many method_missing options available, it might
not be the first one such that gets called.
> 
> Walter
> 
> >
> > --
> > You received this message because you are subscribed to the Google
Groups "Ruby on Rails: Talk" group.
> > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > To view this discussion on the web visit
https://groups.google.com/d/msg/rubyonrails-talk/-/-ncNakybQ-cJ.
> > For more options, visit https://groups.google.com/groups/opt_out.
> >
> >
> 
> --
> You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
> For more options, visit https://groups.google.com/groups/opt_out.
> 
> 
> 
> 
> -- 
> You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
> For more options, visit https://groups.google.com/groups/opt_out.
>  
>  
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.

I would use a before_save or what it is called if I were you.
Am 21.12.2012 19:40 schrieb "Walter Lee Davis"
<waltd-HQgmohHLjDZWk0Htik3J/w@public.gmane.org>:
>
> On Dec 21, 2012, at 1:12 PM, Dan Brooking wrote:
>
> > So is the way I''m doing it right?  Or just a way I happened
to hack it
> to work?
> >
> > The way my code was looking was basically:
> >
> > Page.new(:url => ''http://www.yahoo.com'')
> >
> > class Page < ActiveRecord::Base
> >   attr_accessible :url, :title
> >
> >   after_initialize :parse_page_params
> >
> >   def parse_page_params
> >     @title = "test"
> >   end
> >
>
> Have a look at the documentation for after_initialize -- it runs once,
> after Rails itself is fully initialized. Is that the point at which you
> mean to instantiate the instance variable @title? Which instance of its
> class would it attach to? Can you please describe what you intend to do
> with @title -- where it''s going to be used?
>
> Walter
>
> > and this wasn''t working...  I understand what you said above
about the
> instance variables, methods, initializing, etc.. but still a little unclear
> about why that code doesn''t work as I''m setting it.  Is
it because Rails
> uses the method name of title which hasn''t been initailized in my
> assignment above?
> >
> >
> >
> >
> > On Fri, Dec 21, 2012 at 12:43 PM, Walter Lee Davis
<waltd-HQgmohHLjDZWk0Htik3J/w@public.gmane.org>
> wrote:
> >
> > On Dec 21, 2012, at 12:37 PM, Dan Brooking wrote:
> >
> > > I posted a previous message about overriding initialize...
because I
> was having issues setting some of the parameters.  I have a Page model that
> has:
> > >
> > > attr_accessible :url, :title, :doc, :domain
> > >
> > > and it''s called via:
> > >
> > > Page.new(:url => ''http://www.yahoo.com'')
> > >
> > > Since I''m only passing in the url to new, I needed to
set the other
> parameters.  I was trying to do this via an after_initialize callback which
> wasn''t working so tried overriding initialize... still not
working.
> > >
> > > What I found out was that in my after_initialize, I was referring
to
> title as @title which is why it was not working.  I switched it to
> self.title and it works fine.
> > >
> > > My question is - why?
> >
> > @title is an instance variable. Until you set it, it doesn''t
exist.
> Having a method on the model called title (or an accessor, or some other
> Rails magick) does not instantiate that method''s return until and
unless
> you ask for it by calling the method. Calling self.method_name just makes
> it clear which same-named method you really mean. Self is implied much of
> the time, but when you have all the many method_missing options available,
> it might not be the first one such that gets called.
> >
> > Walter
> >
> > >
> > > --
> > > You received this message because you are subscribed to the
Google
> Groups "Ruby on Rails: Talk" group.
> > > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
> .
> > > To unsubscribe from this group, send email to
>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > > To view this discussion on the web visit
> https://groups.google.com/d/msg/rubyonrails-talk/-/-ncNakybQ-cJ.
> > > For more options, visit https://groups.google.com/groups/opt_out.
> > >
> > >
> >
> > --
> > You received this message because you are subscribed to the Google
> Groups "Ruby on Rails: Talk" group.
> > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > To unsubscribe from this group, send email to
>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > For more options, visit https://groups.google.com/groups/opt_out.
> >
> >
> >
> >
> > --
> > You received this message because you are subscribed to the Google
> Groups "Ruby on Rails: Talk" group.
> > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > To unsubscribe from this group, send email to
>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > For more options, visit https://groups.google.com/groups/opt_out.
> >
> >
>
> --
> You received this message because you are subscribed to the Google Groups
> "Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> For more options, visit https://groups.google.com/groups/opt_out.
>
>
>
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit https://groups.google.com/groups/opt_out.

What I''m trying to do is parse out the title and then save it to the DB
for
quick display on the webpage.

I could do a before_save, hadn''t thought of that, but would I have the
same
issues? I''m basically doing a Page.new(...), a few lines of validation,
and
then Page.save() so before_save would be ok I guess.  Is there typically a
standard way of doing things?


On Fri, Dec 21, 2012 at 4:36 PM, Norbert Melzer
<timmelzer-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> I would use a before_save or what it is called if I were you.
> Am 21.12.2012 19:40 schrieb "Walter Lee Davis"
<waltd-HQgmohHLjDZWk0Htik3J/w@public.gmane.org>:
>
>
>> On Dec 21, 2012, at 1:12 PM, Dan Brooking wrote:
>>
>> > So is the way I''m doing it right?  Or just a way I
happened to hack it
>> to work?
>> >
>> > The way my code was looking was basically:
>> >
>> > Page.new(:url => ''http://www.yahoo.com'')
>> >
>> > class Page < ActiveRecord::Base
>> >   attr_accessible :url, :title
>> >
>> >   after_initialize :parse_page_params
>> >
>> >   def parse_page_params
>> >     @title = "test"
>> >   end
>> >
>>
>> Have a look at the documentation for after_initialize -- it runs once,
>> after Rails itself is fully initialized. Is that the point at which you
>> mean to instantiate the instance variable @title? Which instance of its
>> class would it attach to? Can you please describe what you intend to do
>> with @title -- where it''s going to be used?
>>
>> Walter
>>
>> > and this wasn''t working...  I understand what you said
above about the
>> instance variables, methods, initializing, etc.. but still a little
unclear
>> about why that code doesn''t work as I''m setting it. 
Is it because Rails
>> uses the method name of title which hasn''t been initailized in
my
>> assignment above?
>> >
>> >
>> >
>> >
>> > On Fri, Dec 21, 2012 at 12:43 PM, Walter Lee Davis
<waltd-HQgmohHLjDZWk0Htik3J/w@public.gmane.org>
>> wrote:
>> >
>> > On Dec 21, 2012, at 12:37 PM, Dan Brooking wrote:
>> >
>> > > I posted a previous message about overriding initialize...
because I
>> was having issues setting some of the parameters.  I have a Page model
that
>> has:
>> > >
>> > > attr_accessible :url, :title, :doc, :domain
>> > >
>> > > and it''s called via:
>> > >
>> > > Page.new(:url => ''http://www.yahoo.com'')
>> > >
>> > > Since I''m only passing in the url to new, I needed
to set the other
>> parameters.  I was trying to do this via an after_initialize callback
which
>> wasn''t working so tried overriding initialize... still not
working.
>> > >
>> > > What I found out was that in my after_initialize, I was
referring to
>> title as @title which is why it was not working.  I switched it to
>> self.title and it works fine.
>> > >
>> > > My question is - why?
>> >
>> > @title is an instance variable. Until you set it, it
doesn''t exist.
>> Having a method on the model called title (or an accessor, or some
other
>> Rails magick) does not instantiate that method''s return until
and unless
>> you ask for it by calling the method. Calling self.method_name just
makes
>> it clear which same-named method you really mean. Self is implied much
of
>> the time, but when you have all the many method_missing options
available,
>> it might not be the first one such that gets called.
>> >
>> > Walter
>> >
>> > >
>> > > --
>> > > You received this message because you are subscribed to the
Google
>> Groups "Ruby on Rails: Talk" group.
>> > > To post to this group, send email to
>> rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> > > To unsubscribe from this group, send email to
>>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> > > To view this discussion on the web visit
>> https://groups.google.com/d/msg/rubyonrails-talk/-/-ncNakybQ-cJ.
>> > > For more options, visit
https://groups.google.com/groups/opt_out.
>> > >
>> > >
>> >
>> > --
>> > You received this message because you are subscribed to the Google
>> Groups "Ruby on Rails: Talk" group.
>> > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> > To unsubscribe from this group, send email to
>>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> > For more options, visit https://groups.google.com/groups/opt_out.
>> >
>> >
>> >
>> >
>> > --
>> > You received this message because you are subscribed to the Google
>> Groups "Ruby on Rails: Talk" group.
>> > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> > To unsubscribe from this group, send email to
>>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> > For more options, visit https://groups.google.com/groups/opt_out.
>> >
>> >
>>
>> --
>> You received this message because you are subscribed to the Google
Groups
>> "Ruby on Rails: Talk" group.
>> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> To unsubscribe from this group, send email to
>>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> For more options, visit https://groups.google.com/groups/opt_out.
>>
>>
>>  --
> You received this message because you are subscribed to the Google Groups
> "Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> For more options, visit https://groups.google.com/groups/opt_out.
>
>
>
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit https://groups.google.com/groups/opt_out.

On Dec 21, 6:12 pm, Dan Brooking
<dmbrook...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> class Page < ActiveRecord::Base
>   attr_accessible :url, :title
>
>   after_initialize :parse_page_params
>
>   def parse_page_params
>     @title = "test"
>   end
>
> and this wasn''t working...  I understand what you said above about
the
> instance variables, methods, initializing, etc.. but still a little unclear
> about why that code doesn''t work as I''m setting it.  Is
it because Rails
> uses the method name of title which hasn''t been initailized in my
> assignment above?
>
Because rails doesn''t use individual instance variables to store your
attributes (whether they''ve been marked as attr_accessible makes no
difference)

title = "foo"

Doesn''t work because ruby assumes that you want to assign to the local
variable called title. Doing self.title = makes it clear that you want
to call the title= accessor

Fred
> On Fri, Dec 21, 2012 at 12:43 PM, Walter Lee Davis
<wa...-HQgmohHLjDZWk0Htik3J/w@public.gmane.org>wrote:
>
>
>
>
>
>
>
>
>
> > On Dec 21, 2012, at 12:37 PM, Dan Brooking wrote:
>
> > > I posted a previous message about overriding initialize...
because I was
> > having issues setting some of the parameters.  I have a Page model
that has:
>
> > > attr_accessible :url, :title, :doc, :domain
>
> > > and it''s called via:
>
> > > Page.new(:url => ''http://www.yahoo.com'')
>
> > > Since I''m only passing in the url to new, I needed to
set the other
> > parameters.  I was trying to do this via an after_initialize callback
which
> > wasn''t working so tried overriding initialize... still not
working.
>
> > > What I found out was that in my after_initialize, I was referring
to
> > title as @title which is why it was not working.  I switched it to
> > self.title and it works fine.
>
> > > My question is - why?
>
> > @title is an instance variable. Until you set it, it doesn''t
exist. Having
> > a method on the model called title (or an accessor, or some other
Rails
> > magick) does not instantiate that method''s return until and
unless you ask
> > for it by calling the method. Calling self.method_name just makes it
clear
> > which same-named method you really mean. Self is implied much of the
time,
> > but when you have all the many method_missing options available, it
might
> > not be the first one such that gets called.
>
> > Walter
>
> > > --
> > > You received this message because you are subscribed to the
Google
> > Groups "Ruby on Rails: Talk" group.
> > > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh4Ykp1iOSErHA@public.gmane.orgm.
> > > To unsubscribe from this group, send email to
> >
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > > To view this discussion on the web visit
> >https://groups.google.com/d/msg/rubyonrails-talk/-/-ncNakybQ-cJ.
> > > For more options, visithttps://groups.google.com/groups/opt_out.
>
> > --
> > You received this message because you are subscribed to the Google
Groups
> > "Ruby on Rails: Talk" group.
> > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > To unsubscribe from this group, send email to
> >
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> > For more options, visithttps://groups.google.com/groups/opt_out.
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.

I do something similar in a project of mine. I have an API key and retrieve
user information after he logs in. This works very fine in an after-find,
why should that not work in a before_save?

Can''t provide the source right now. I have no access until Jan 8th.
Am 21.12.2012 22:39 schrieb "Dan Brooking"
<dmbrooking-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:
> What I''m trying to do is parse out the title and then save it to
the DB
> for quick display on the webpage.
>
> I could do a before_save, hadn''t thought of that, but would I have
the
> same issues? I''m basically doing a Page.new(...), a few lines of
> validation, and then Page.save() so before_save would be ok I guess.  Is
> there typically a standard way of doing things?
>
>
> On Fri, Dec 21, 2012 at 4:36 PM, Norbert Melzer
<timmelzer-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>wrote:
>
>> I would use a before_save or what it is called if I were you.
>> Am 21.12.2012 19:40 schrieb "Walter Lee Davis"
<waltd-HQgmohHLjDZWk0Htik3J/w@public.gmane.org>:
>>
>>
>>> On Dec 21, 2012, at 1:12 PM, Dan Brooking wrote:
>>>
>>> > So is the way I''m doing it right?  Or just a way I
happened to hack it
>>> to work?
>>> >
>>> > The way my code was looking was basically:
>>> >
>>> > Page.new(:url => ''http://www.yahoo.com'')
>>> >
>>> > class Page < ActiveRecord::Base
>>> >   attr_accessible :url, :title
>>> >
>>> >   after_initialize :parse_page_params
>>> >
>>> >   def parse_page_params
>>> >     @title = "test"
>>> >   end
>>> >
>>>
>>> Have a look at the documentation for after_initialize -- it runs
once,
>>> after Rails itself is fully initialized. Is that the point at which
you
>>> mean to instantiate the instance variable @title? Which instance of
its
>>> class would it attach to? Can you please describe what you intend
to do
>>> with @title -- where it''s going to be used?
>>>
>>> Walter
>>>
>>> > and this wasn''t working...  I understand what you
said above about the
>>> instance variables, methods, initializing, etc.. but still a little
unclear
>>> about why that code doesn''t work as I''m setting
it.  Is it because Rails
>>> uses the method name of title which hasn''t been
initailized in my
>>> assignment above?
>>> >
>>> >
>>> >
>>> >
>>> > On Fri, Dec 21, 2012 at 12:43 PM, Walter Lee Davis
<waltd-HQgmohHLjDZWk0Htik3J/w@public.gmane.org>
>>> wrote:
>>> >
>>> > On Dec 21, 2012, at 12:37 PM, Dan Brooking wrote:
>>> >
>>> > > I posted a previous message about overriding
initialize... because I
>>> was having issues setting some of the parameters.  I have a Page
model that
>>> has:
>>> > >
>>> > > attr_accessible :url, :title, :doc, :domain
>>> > >
>>> > > and it''s called via:
>>> > >
>>> > > Page.new(:url =>
''http://www.yahoo.com'')
>>> > >
>>> > > Since I''m only passing in the url to new, I
needed to set the other
>>> parameters.  I was trying to do this via an after_initialize
callback which
>>> wasn''t working so tried overriding initialize... still not
working.
>>> > >
>>> > > What I found out was that in my after_initialize, I was
referring to
>>> title as @title which is why it was not working.  I switched it to
>>> self.title and it works fine.
>>> > >
>>> > > My question is - why?
>>> >
>>> > @title is an instance variable. Until you set it, it
doesn''t exist.
>>> Having a method on the model called title (or an accessor, or some
other
>>> Rails magick) does not instantiate that method''s return
until and unless
>>> you ask for it by calling the method. Calling self.method_name just
makes
>>> it clear which same-named method you really mean. Self is implied
much of
>>> the time, but when you have all the many method_missing options
available,
>>> it might not be the first one such that gets called.
>>> >
>>> > Walter
>>> >
>>> > >
>>> > > --
>>> > > You received this message because you are subscribed to
the Google
>>> Groups "Ruby on Rails: Talk" group.
>>> > > To post to this group, send email to
>>> rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>>> > > To unsubscribe from this group, send email to
>>>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>>> > > To view this discussion on the web visit
>>> https://groups.google.com/d/msg/rubyonrails-talk/-/-ncNakybQ-cJ.
>>> > > For more options, visit
https://groups.google.com/groups/opt_out.
>>> > >
>>> > >
>>> >
>>> > --
>>> > You received this message because you are subscribed to the
Google
>>> Groups "Ruby on Rails: Talk" group.
>>> > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
>>> .
>>> > To unsubscribe from this group, send email to
>>>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>>> > For more options, visit
https://groups.google.com/groups/opt_out.
>>> >
>>> >
>>> >
>>> >
>>> > --
>>> > You received this message because you are subscribed to the
Google
>>> Groups "Ruby on Rails: Talk" group.
>>> > To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
>>> .
>>> > To unsubscribe from this group, send email to
>>>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>>> > For more options, visit
https://groups.google.com/groups/opt_out.
>>> >
>>> >
>>>
>>> --
>>> You received this message because you are subscribed to the Google
>>> Groups "Ruby on Rails: Talk" group.
>>> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>>> To unsubscribe from this group, send email to
>>>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>>> For more options, visit https://groups.google.com/groups/opt_out.
>>>
>>>
>>>  --
>> You received this message because you are subscribed to the Google
Groups
>> "Ruby on Rails: Talk" group.
>> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> To unsubscribe from this group, send email to
>>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> For more options, visit https://groups.google.com/groups/opt_out.
>>
>>
>>
>
>  --
> You received this message because you are subscribed to the Google Groups
> "Ruby on Rails: Talk" group.
> To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To unsubscribe from this group, send email to
>
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> For more options, visit https://groups.google.com/groups/opt_out.
>
>
>
-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit https://groups.google.com/groups/opt_out.

On Friday, 21 December 2012 13:12:35 UTC-5, Dan Brooking
wrote:
>
> So is the way I''m doing it right?  Or just a way I happened to
hack it to
> work?
>
> The way my code was looking was basically:
>
> Page.new(:url => ''http://www.yahoo.com'')
>
> class Page < ActiveRecord::Base
>   attr_accessible :url, :title
>
>   after_initialize :parse_page_params
>
>   def parse_page_params
>     @title = "test"
>   end
>
> and this wasn''t working...  I understand what you said above about
the
> instance variables, methods, initializing, etc.. but still a little unclear
> about why that code doesn''t work as I''m setting it.  Is
it because Rails
> uses the method name of title which hasn''t been initailized in my 
> assignment above?
>
>
It sounds like you''ve got attr_accessible and attr_accessor somewhat 
entangled in your mental model. They aren''t really the same thing at
all:

- attr_accessible: specifies which attributes are mass-assignable (through 
things like Page.new(:some_attribute => ''foo'')) and which
have to be
assigned individually.

- attr_accessor: creates two accessor methods that wrap an instance 
variable. So this:

attr_accessor :something

is shorthand for this:

def something
  @something
end

def something=(v)
  @something = v
end

Occasionally you''ll even see both used for a particular name, as the 
developer wants to create an attribute that isn''t persisted to the
database
but can be mass-assigned (from a form submission, for instance).

--Matt Jones

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To view this discussion on the web visit
https://groups.google.com/d/msg/rubyonrails-talk/-/idE5s9Ki5-cJ.
For more options, visit https://groups.google.com/groups/opt_out.

Frederick Cheung wrote in post #1089897:
>
> Because rails doesn''t use individual instance variables to store
your
> attributes (whether they''ve been marked as attr_accessible makes
no
> difference)
>
> title = "foo"
>
> Doesn''t work because ruby assumes that you want to assign to the
local
> variable called title. Doing self.title = makes it clear that you want
> to call the title= accessor
>
While true, that has nothing to do with the op''s problem--the op is 
assigning to an @ variable, and an @ variable, like @title, can never be 
a local variable.  There is only one way for ruby to interpret an 
assignment like:

@title = some_value

>Is there typically a standard way of doing things?
Yes.  Always use the accessor method to set or get the value of an 
instance variable.  Here is an example of how things can go wrong:

class Dog
  def title=(val)
    @title = val.capitalize
  end

  def do_stuff
    @title = "mr."
    @title + " Dog"
  end
end

puts Dog.new.do_stuff

--output:--
mr. Dog


And here is how to correct the problem:

class Dog
  def title=(val)
    @title = val.capitalize
  end

  def do_stuff
    self.title = "mr."
    @title + " Dog"
  end
end

puts Dog.new.do_stuff


What you did is bypass an accessor method, which you did not define and 
therefore are blissfully unaware of what it does, and your results 
showed that the accessor method did something critical.

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

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit https://groups.google.com/groups/opt_out.

7stud -- wrote in post #1089991:
>
> And here is how to correct the problem:
>
> class Dog
>   def title=(val)
>     @title = val.capitalize
>   end
>
>   def do_stuff
>     self.title = "mr."
>     title + " Dog"
>   end
> end
>
> puts Dog.new.do_stuff
>
>

That should be:

class Dog
  def title=(val)
    @title = val.capitalize
  end

  #MISSING getter **********
  def title
    @title
  end

  def do_stuff
    self.title = "mr."
    title + " Dog"
  end
end

puts Dog.new.do_stuff

--output:--
Mr. Dog

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

-- 
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
For more options, visit https://groups.google.com/groups/opt_out.