Question

My form has the following:

<%= f.select(:amount, Order::AMOUNT_VALUES, {:blank => false}) %> 

My model has:

  AMOUNT_VALUES = { '$ 0.50' => 0.5, '$ 1' => 1, '$ 2' => 2, '$ 5' => 5, '$ 10' => 10 }
  validate :amount_values_to_be_of_certain_values

  def amount_values_to_be_of_certain_values
    puts self.amount
    unless AMOUNT_VALUES.has_value? self.amount
      errors.add(:amount, 'not a valid field')
    end
  end

If I select 0.5 and submit the form. The form complains saying “Amount not a valid field”. If I select one of the other values, the form submits fine.

It seems the problem is with a decimal point that starts with 0.

What is wrong here?

Answer 1

If you’re storing amount in an integer field, then it’s going to round any floating point numbers you put into it down. That’s why self.amount.to_f is 0.0, because putting 0.5 into an integer field changes it to 0, and 0.to_f is 0.0.