Validation

Rails
1

Hi,

I have one problem,

Regarding Medical store distributuin

   Store have two users i mean two sales persons, they are

distributing medicine to patients.

   Store having 50 colpol tablets, both users are trying to sale 40

colpol tablets at a same time, it means 80 tablets but store having 50
colpols only.

   For this i want reserve the stock while form entry itself,as well

as i dont want to use database level.

  any ruby or rails concept is there....?

advance thanks

2

actually, if it is the same database, then there is no way to happen at
the same time, right?

I don’t know, maybe something like this:

class Tablet < ActiveRecord::Base

validate :must_have_in_stock

def must_have_in_stock
qnt = Tablet.find(product_id).quantity
erros.add(:quantity, ‘There is only ’ + qnt + ’ in stock.’)
if quantity > qnt
end
end

3

On Jun 15, 7:00 am, Le Sa [email protected] wrote:

actually, if it is the same database, then there is no way to happen at
the same time, right?

Unfortunately, not true.

Anything working purely at the ruby level (such as a validation) will
run into race conditions doing this. One of Rails’ answers to this is
optimistic locking (described in the active record api docs).

Fred

4

Frederick C. wrote:

On Jun 15, 7:00�am, Le Sa [email protected] wrote:

actually, if it is the same database, then there is no way to happen at
the same time, right?

Unfortunately, not true.

Anything working purely at the ruby level (such as a validation) will
run into race conditions doing this. One of Rails’ answers to this is
optimistic locking (described in the active record api docs).

Fred

Mr. Frederick C. thanks for replying,

As u said, backend i have validated everythig. the person who submits
first get saved and for the second person it should display stock not
available…

But my expectation is once the first user has selected the quantity
then for the second user the stock displayed should be available
quantity minus first user selected quantity.

note : This should work before both the users save the form.

5

Frederick C. wrote:

On Jun 15, 8:28�am, Gopi G. [email protected]
wrote:

� As u said, backend i have validated everythig. the person who submits
first get saved and for the second person it should display stock not
available…

� But my expectation is once the first user has selected the quantity
then for the second user the stock displayed should be available
quantity minus first user selected quantity.

note : This should work before both the users save the form.

Then you’re going to have to spend quite a lot of time coming up with
some sort of ajaxy notification thing to track all this.

Fred

yes mr. Fred

for that we need to keep the data commonly for all users , where we can
keep except database?.

whether we can save it anywhere in our application, that can be
editable?

6

On Jun 15, 8:28 am, Gopi G. [email protected]
wrote:

As u said, backend i have validated everythig. the person who submits
first get saved and for the second person it should display stock not
available…

But my expectation is once the first user has selected the quantity
then for the second user the stock displayed should be available
quantity minus first user selected quantity.

note : This should work before both the users save the form.

Then you’re going to have to spend quite a lot of time coming up with
some sort of ajaxy notification thing to track all this.

Fred

7

Gopi G. wrote:

Frederick C. wrote:

On Jun 15, 8:28�am, Gopi G. [email protected]
wrote:

� As u said, backend i have validated everythig. the person who submits
first get saved and for the second person it should display stock not
available…

� But my expectation is once the first user has selected the quantity
then for the second user the stock displayed should be available
quantity minus first user selected quantity.

note : This should work before both the users save the form.

Then you’re going to have to spend quite a lot of time coming up with
some sort of ajaxy notification thing to track all this.

Fred

yes mr. Fred

for that we need to keep the data commonly for all users , where we can
keep except database?.

whether we can save it anywhere in our application, that can be
editable?

once our input get saved, then we will detete that user related data
from that storage. if we go for data base using ajax it will slow in
frontend itself.