I have a model where I need to calculate one of the fields when I create a new instance. It seems to me that I should do this in the model code and that I should override the new and/or create methods. Is this the right approach and, if so, how can I execute the existing method but add on my calculation? I want something like: def create -Do the original create first- field = calculated_value save self end How do I call the original create method and use the parameters passed? Also, should I be overriding new or create or both? Thanks for any help. Julian -- Posted via http://www.ruby-forum.com/.
> How do I call the original create method and use the parameters passed? > Also, should I be overriding new or create or both?I''m new at this, but I think you''ll want to take a lot at callbacks. http://api.rubyonrails.com/classes/ActiveRecord/Callbacks.html
def test(parameters) super end The super method calls the original method (eg. test) in the superclass and passes the same parameters as the originally invoked method. -John -- John Smilanick Computing Staff - Webmaster Kavli Institute for Theoretical Physics University of California, Santa Barbara jsmilani@kitp.ucsb.edu (805) 893-6307 On Mar 14, 2006, at 1:26 PM, Julian Gall wrote:> I have a model where I need to calculate one of the fields when I > create > a new instance. It seems to me that I should do this in the model code > and that I should override the new and/or create methods. > > Is this the right approach and, if so, how can I execute the existing > method but add on my calculation? > > I want something like: > > def create > -Do the original create first- > field = calculated_value > save > self > end > > How do I call the original create method and use the parameters > passed? > Also, should I be overriding new or create or both? > > Thanks for any help. > > Julian > > -- > Posted via http://www.ruby-forum.com/. > _______________________________________________ > Rails mailing list > Rails@lists.rubyonrails.org > http://lists.rubyonrails.org/mailman/listinfo/rails-------------- next part -------------- An HTML attachment was scrubbed... URL: http://wrath.rubyonrails.org/pipermail/rails/attachments/20060314/4c63a20e/attachment.html
>> Also, should I be overriding new or create or both?overriding new should be enough since create calls new anyway. # File vendor/rails/activerecord/lib/active_record/base.rb, line 443 443: def create(attributes = nil) 444: if attributes.is_a?(Array) 445: attributes.collect { |attr| create(attr) } 446: else 447: attributes.reverse_merge!(scope(:create)) if scoped? (:create) 448: 449: object = new(attributes) 450: object.save 451: object 452: end 453: end -John -- John Smilanick Computing Staff - Webmaster Kavli Institute for Theoretical Physics University of California, Santa Barbara jsmilani@kitp.ucsb.edu (805) 893-6307 On Mar 14, 2006, at 3:51 PM, John Smilanick wrote:> def test(parameters) > super > end > > The super method calls the original method (eg. test) in the > superclass and passes the same parameters as the originally invoked > method. > > -John > > -- > John Smilanick > Computing Staff - Webmaster > Kavli Institute for Theoretical Physics > University of California, Santa Barbara > jsmilani@kitp.ucsb.edu > (805) 893-6307 > > > On Mar 14, 2006, at 1:26 PM, Julian Gall wrote: > >> I have a model where I need to calculate one of the fields when I >> create >> a new instance. It seems to me that I should do this in the model >> code >> and that I should override the new and/or create methods. >> >> Is this the right approach and, if so, how can I execute the existing >> method but add on my calculation? >> >> I want something like: >> >> def create >> -Do the original create first- >> field = calculated_value >> save >> self >> end >> >> How do I call the original create method and use the parameters >> passed? >> >> >> Thanks for any help. >> >> Julian >> >> -- >> Posted via http://www.ruby-forum.com/. >> _______________________________________________ >> Rails mailing list >> Rails@lists.rubyonrails.org >> http://lists.rubyonrails.org/mailman/listinfo/rails > > > _______________________________________________ > Rails mailing list > Rails@lists.rubyonrails.org > http://lists.rubyonrails.org/mailman/listinfo/rails-------------- next part -------------- An HTML attachment was scrubbed... URL: http://wrath.rubyonrails.org/pipermail/rails/attachments/20060314/1394d39a/attachment-0001.html
Neither :)
Override initialize. Create calls new internally, and new calls initialize.
class Person < ActiveRecord::Base
alias :old_initialize :initialize
def initialize(attributes = nil)
old_initialize(attributes)
# Do whatever you want in here.
end
end
Note that your customised initialize method will be called for any Person
object that is instantiated.
-Jonathan.
On 3/15/06, John Smilanick <jsmilani@kitp.ucsb.edu>
wrote:>
> Also, should I be overriding new or create or both?
>
>
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Jonathan Viney wrote:> Neither :) > > Override initialize. Create calls new internally, and new calls > initialize.Thanks Jonathan. That''s just what I needed. Julian -- Posted via http://www.ruby-forum.com/.
Please help me understand this.
I would thing that you would be able to simply implement your own initialize
method and perform a super inside, like this:
class Person < ActiveRecord::Base
def initialize(*args)
super(*args)
# Do whatever you want in here.
end
end
Yet this is not working for me.
On 3/15/06, Julian Gall <julian.gall@gmail.com>
wrote:>
> Jonathan Viney wrote:
> > Neither :)
> >
> > Override initialize. Create calls new internally, and new calls
> > initialize.
>
> Thanks Jonathan. That''s just what I needed.
>
> Julian
>
> --
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
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Nevermind. With additional searching I found an explanation at: http://www.ruby-forum.com/topic/17456#11446 And this helpful blog entry: http://blog.teksol.info/articles/2005/12/14/setting-default-values-in-models On 6/11/06, Kelly Felkins <railsinator@gmail.com> wrote:> > Please help me understand this. > > I would thing that you would be able to simply implement your own > initialize method and perform a super inside, like this: > > class Person < ActiveRecord::Base > def initialize(*args) > super(*args) > > # Do whatever you want in here. > end > end > > Yet this is not working for me. > > > On 3/15/06, Julian Gall < julian.gall@gmail.com> wrote: > > > > Jonathan Viney wrote: > > > Neither :) > > > > > > Override initialize. Create calls new internally, and new calls > > > initialize. > > > > Thanks Jonathan. That''s just what I needed. > > > > Julian > > > > -- > > Posted via http://www.ruby-forum.com/ . > > _______________________________________________ > > Rails mailing list > > Rails@lists.rubyonrails.org > > http://lists.rubyonrails.org/mailman/listinfo/rails > > > >-------------- next part -------------- An HTML attachment was scrubbed... URL: http://wrath.rubyonrails.org/pipermail/rails/attachments/20060611/fdcb1788/attachment.html