Calculating and inserting value into table column using rails - ruby-on-rails

Question

Hi I'm a newbie to Rails. So pardon if this is a silly question.
I'm working on a project where I need to calculate the Bank Balance and Cashbox balance in a Transaction. So this depends upon the type of transaction "Debit/Credit" and type of payment "Online Payment/Cheque/Cash". There is only one model involved and that is Transaction Model and transactions table. So this is what I'm doing,
transactions_controller
def create
#transaction = Transaction.create(transaction_params)
#amount = transaction_params[:amount].to_f
#cashbox = transaction_params[:cashbox].to_f
#bank = transaction_params[:bank].to_f
if transaction_params[:t_type] == "Debit"
if transaction_params[:t_method] == "Cash"
#cashbox -= #amount
transaction_params[:cashbox] = #cashbox.to_s
else
#bank -= #amount
transaction_params[:bank] = #bank.to_s
end
elsif transaction_params[:t_type] == "Credit"
if transaction_params[:t_method] == "Cash"
#cashbox += #amount
transaction_params[:cashbox] = #cashbox.to_s
else
#bank += #amount
transaction_params[:bank] = #bank.to_s
end
end
if #transaction.save
redirect_to #transaction
else
render 'new'
end
end
def transaction_params
params.require(:transaction).permit(:date, :notes, :t_type, :t_method, :amount, :paid_by, :paid_to, :cashbox, :bank, :house_id, :expense_for)
end`
Transaction Model
class Transaction < ActiveRecord::Base
end
But when I submit the form containing all the values, the calculation part does't happen and rails inserts only the values submitted in the form.
How to calculate cashbox balance and bank balance on submit from the form and store the updated values in the table?
Also, kindly suggest if there are any better ways to do this.

Answer 1

You need to put this functionality to the model and update object before rendering (if i understood you right). Now you never save the changes into the object.

Answer 2

Your logic is confuse, let read more resful of rails.
- First: you can't save, after that create Transaction again.
- Second: you created transaction and below don't see updating that transaction should of course it be not changed.
Let try yourself:
def create
#amount = transaction_params[:amount].to_f
#cashbox = transaction_params[:cashbox].to_f
#bank = transaction_params[:bank].to_f
if transaction_params[:t_type] == "Debit"
if transaction_params[:t_method] == "Cash"
#cashbox -= #amount
transaction_params[:cashbox] = #cashbox.to_s
else
#bank -= #amount
transaction_params[:bank] = #bank.to_s
end
elsif transaction_params[:t_type] == "Credit"
if transaction_params[:t_method] == "Cash"
#cashbox += #amount
transaction_params[:cashbox] = #cashbox.to_s
else
#bank += #amount
transaction_params[:bank] = #bank.to_s
end
end
#transaction = Transaction.new transaction_params
if #transaction.save
redirect_to #transaction
else
render 'new'
end
end
def transaction_params
params.require(:transaction).permit(:date, :notes, :t_type, :t_method, :amount, :paid_by, :paid_to, :cashbox, :bank, :house_id, :expense_for)
end`

Answer 3

You've got a few things in a bit of a muddle I think:
1) if #transaction.save
Here you're trying to save the transaction and only continuing if you do so successfully. Where is #transaction getting set up though? Presumably in some kind of before_filter but I suspect you don't need that in this case.
2) #transaction = Transaction.create(transaction_params)
Now you're creating, and saving to the database, a new Transaction object base on the parameters that are being submitted from the form (but only if it passes validation).
3) Then you do a load of work to calculate some parameters that appear to be transaction parameters. At this point though you've already created the transaction object with the parameters that were submitted. You add all these to the params hash which is predominantly used to pass web request parameters in (yes, you can use it for other things but I'd avoid doing that just yet).
Now, the most simple fix is probably to move your Transaction.create line to after all your params changes because then you'll be creating a transaction with the parameters you want. I wouldn't advocate that though. It seems like this code would be better moved to the Transaction model and have a method to apply the values to a transaction after you've built it.
(I'd also question if you've got your modelling quite right. You seem to be passing in a #bank value as part of the web request and then applying the value of the transaction your creating to it to give your bank value on the transaction. Of course, I'm not sure of your exact requirements but this seems like a potentially problematic approach. One for a different question perhaps).