Rails - Jun 2006 - how do I validate currency format if I am storing in cents?

Hi all -

To avoid floating point issues, I''ve decided to store monetary values
in
cents in the database.  However, the user will enter these in dollars 
and cents.  Two questions:

1) How do I do the validation for the currency format?  It looks like 
ActiveRecord truncates the cents since it thinks the field type is a 
Fixnum. Am I forced to do validation in the controller?

2) Where is the appropriate place to do the conversion from dollars to 
cents?  I initially was thinking of doing the conversion in 
before_create or before_update, but again, it seems like the value is 
truncated as described above.

Thanks.

Ken

Kenneth Liu wrote:
> Hi all -
> 
> To avoid floating point issues, I''ve decided to store monetary
values in
> cents in the database.  However, the user will enter these in dollars
> and cents.  Two questions:
> 
> 1) How do I do the validation for the currency format?  It looks like
> ActiveRecord truncates the cents since it thinks the field type is a
> Fixnum. Am I forced to do validation in the controller?
> 
> 2) Where is the appropriate place to do the conversion from dollars to
> cents?  I initially was thinking of doing the conversion in
> before_create or before_update, but again, it seems like the value is
> truncated as described above.
Here''s what I do for conversion:

  def amount=(new_amount)
    write_attribute("amount", (new_amount.to_f * 100.0).to_i)
  end

  def amount
    read_attribute("amount").to_f / 100.0
  end

I''m not quite sure what I''d validate about it, though:-)

--Al Evans

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

Al, that puts me on the right track for my second question.

As for the validation, I want to validate to make sure the user did not 
enter something that doesn''t match /\d+\.\d{2}/.  Like a string, for 
example.

Do you have a validation like the following?

validates_numericality_of :amount, :only_integer => true

If the user enters a string, doesn''t that break your amount accessors?

Ken


Al Evans wrote:
> Kenneth Liu wrote:
>   
>> Hi all -
>>
>> To avoid floating point issues, I''ve decided to store monetary
values in
>> cents in the database.  However, the user will enter these in dollars
>> and cents.  Two questions:
>>
>> 1) How do I do the validation for the currency format?  It looks like
>> ActiveRecord truncates the cents since it thinks the field type is a
>> Fixnum. Am I forced to do validation in the controller?
>>
>> 2) Where is the appropriate place to do the conversion from dollars to
>> cents?  I initially was thinking of doing the conversion in
>> before_create or before_update, but again, it seems like the value is
>> truncated as described above.
>>     
>
> Here''s what I do for conversion:
>
>   def amount=(new_amount)
>     write_attribute("amount", (new_amount.to_f * 100.0).to_i)
>   end
>
>   def amount
>     read_attribute("amount").to_f / 100.0
>   end
>
> I''m not quite sure what I''d validate about it, though:-)
>
> --Al Evans
>
>

Kenneth Liu wrote:

> If the user enters a string, doesn''t that break your amount
accessors?
Nope. They just come out to 0. Try "fred".to_f

--Al Evans

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