Rails - Dec 2005 - Unable to call method in same class

Hi,

I have the following two methods in my class:

  def self.decrease_credits(amount, user_id)
    user = User.find(user_id)
    company = Company.find(user.company_id)
    credits_new_saldo = company.credits - amount
    company.update_attribute(:credits, credits_new_saldo)
  end

  def self.available_credits(user_id)
    user = User.find(user_id)
    company = Company.find(user.company_id)
    return company.credits
  end

They both work, but since the code of the second method is the same as 
the first three lines of the method self.decrease_credits, I would like 
to rewrite it as:

  def self.decrease_credits(amount, user_id)
    credits_new_saldo = available_credits(user_id) - amount
    company.update_attribute(:credits, credits_new_saldo)
  end

But then I get the error that available_credits is not known in the 
class. Why is this not working and what is the right way? All help is 
greatly appreciated. Thanks.

Kind regards,

Nick

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Nick Snels wrote:
> Hi,
> 
> I have the following two methods in my class:
> 
>   def self.decrease_credits(amount, user_id)
>     user = User.find(user_id)
>     company = Company.find(user.company_id)
Why not "company = user.company"?

> They both work, but since the code of the second method is the same as 
> the first three lines of the method self.decrease_credits, I would like 
> to rewrite it as:
> 
>   def self.decrease_credits(amount, user_id)
>     credits_new_saldo = available_credits(user_id) - amount
self.available_credits(user_id)

But all of this seems way too complicated. Why don''t you use instance 
methods?

class User
  def available_credits
    self.company.credits
  end

  def decrease_credits(amount)
    credits_new_saldo = self.available_credits - amount
    self.company.update_attribute(:credits, credits_new_saldo)
  end
end

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Hi Andreas,

thanks for your help. Really, really helpful. Too complicated you say, 
well and I thought I was doing it the simple way! Thanks for pointing me 
to instance methods, a piece of Rails I will be exploring and definitely 
using more and more in the future. It is really ridiculously easy, wow! 
:D Thanks.

Nick


Andreas Schwarz wrote:
> 
> But all of this seems way too complicated. Why don''t you use
instance
> methods?
> 
> class User
>   def available_credits
>     self.company.credits
>   end
> 
>   def decrease_credits(amount)
>     credits_new_saldo = self.available_credits - amount
>     self.company.update_attribute(:credits, credits_new_saldo)
>   end
> end

-- 
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Andreas Schwarz wrote:
> Nick Snels wrote:
>> They both work, but since the code of the second method is the same as 
>> the first three lines of the method self.decrease_credits, I would like
>> to rewrite it as:
>> 
>>   def self.decrease_credits(amount, user_id)
>>     credits_new_saldo = available_credits(user_id) - amount
> 
> self.available_credits(user_id)
That''s wrong, it should be:
self.class.available_credits(user_id)

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