Question

The user has a balance (user.balance).

The user can post bets on a game (bet.amount).

How could I stop the user from betting more than what is in their balance?

I assume I could create a validation that looks something like this?

def enough_funds?
  @bet.bet_amount > self.current_user.balance 
  flash[:notice] = "You do not have the available funds for this bet"
end

I’m still new to rails, be gentle 🙂

Answer 1

You’re on the right track:

class Bet < ActiveRecord::Base
  belongs_to :user

  validate :funds_suffiency

  def funds_sufficiency
    errors.add :bet_amount, "is more than your available balance" if bet_amount < user.balance
  end
end

If Bet‘s :bet_amount is less than the related User‘s available :balance, the error will be added to :bet_amount attribute, invalidating the model instance.