Where are my field values?!

I have created a function in model that retrieves the idea of creating
it uisng this link:
http://stackoverflow.com/questions/1330273/how-to-calculate-difference-of-two-fields-on-form-submit-ruby-on-rails

The aim of the function is to calculate the following formula, provided
that all are fields in the table:

quantity_sold = receive + deliver

This is how my model looks like:

Class Iteminfo < ActiveRecord::Base
attr_accessor :receive, :deliver
before_create :calculate_quantity_sold

private
def calculate_quantity_sold
self.quantity_sold = receive.to_i + deliver.to_i
end
end

Now, when I enter values for the "deliver" and "receive" fields, say:

receive = 10
deliver = 10

I get the following value for "quantity_sold" ---> 20

Where is the problem?

The problem is that when I enter the values on the form for the
"receive" and "deliver" fields, and then hit the "Create" buttom, in the
"show" page, I get a "20" beside the "quantity_sold" field shown and
EMPTY fields for "deliver" and "receive".

The other problem is that when I for example want to see the data in my
table using Firefoxe's SQLite Manager I do NOT get any data shown
although I can see it in the form "index" page.

What is the problem here?

Thanks.

Regarding the fields in SQL Manager, I found that I was browsing the
wrong database.

And, in my model in order to get values for "receive" amd "deliver" I
had to remove this line:

attr_accessor :receive, :deliver

The function should bbe

Def quantity_sold
Delivered_item + item_price
End

Then call quantity_sold.

Removing attr_accesible is a very bat idea.

topposted again without any sign of trimming:

The function should bbe

Def quantity_sold
Delivered_item + item_price
End

If you're going to write example code, please take the time to make
sure it might even work... you should be aware of the case-sensitivity
of Ruby.
What on earth does "item_price" have to do with quantity sold? Where
has the OP mentioned that? And infact, where has "Delivered_item" come
from? Can I just check that you replied to the right message?

Then call quantity_sold.

The OP has stated he wants to store the quantity_sold in the DB - how
will this method help achieve that?

Removing attr_accesible is a very bat idea.

He hasn't said anything about removing attr_accesible - he's removed
the attr_accessor definitions - which is correct if he's got fields
for those values he doesn't need to create accessors for them.

The question might be to check with the OP whether he *really* needs
to store the calculated value, or whether it would just be easier to
have a method (similar to the one you proposed, but using the correct
calculation) to return the value when asked. I suppose it depends
whether he's doing a lot of DB queries on the quantity_sold - in which
case it might be better to have it in the DB, of if it's just for use
in views, then possible a (memoized) calculated value might be
"better" to prevent any risk of the values getting out-of sync
(nothing worse than someone running an update on the db and changing
values without updating the calculated values...)

Sorry im replying from i new phone and is 5:00 am where i live , i
should have waited until i get to my pc and drink some coffe

ok now im awake and on my pc , yes my reply made no sense, the problem is that i cant trimm comments from the phone and i cant see the op as i reply, and since i had just woke up , i couldnt quite remember what the op was about as i reply.

I wont repeat that.

Thanks a lot everyone.