Question

My form has:

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

My model has:

AMOUNT_VALUES = { '$ 0' => 0, '$ 1' => 1, '$ 2' => 2, '$ 5' => 5, '$ 10' => 10 }.

If user select $2 and submits form. The next time he goes back to the form, I need it only to display everything above $2 in the select box. Therefore, the options should be $5 and $10 only.

How can this be achieved?

Answer 1

I recently wrote some helper code that helped me rule out days of the week where a store had already posted business hours for. It shouldn’t be too hard to adapt to your specifications.

Updated: Added question-specific code and updated with a more-efficient reject block.

module HoursHelper
  ...
  def generateDayStrings (unavailable_days)
    all_days = [ ['Sunday',    'Sun'], 
                 ['Monday',    'Mon'],
                 ['Tuesday',   'Tue'],
                 ['Wednesday', 'Wed'],
                 ['Thursday',  'Thu'],
                 ['Friday',    'Fri'],
                 ['Saturday',  'Sat'] ]
    all_days.reject do |day|
      (day - unavailable_days).size != 2
    end
  end
  ...
end

<%= f.select :day_of_week, generateDayStrings(@days_with_hours) %>

# @days_with_hours = ['Mon', 'Tue', 'Wed', 'Thu', 'Fri']
# generateDayStrings(@days_with_hours) = [ ['Sunday', 'Sun'], ['Saturday', 'Sat'] ]

For your particular codebase, it’d probably look something like this:

module PaymentsHelper
  ...
  def generatePaymentAmountSelectArray (unavailable_denoms)
    all_denoms = [ ['$ 0',  '0'], 
                   ['$ 1',  '1'],
                   ['$ 2',  '2'],
                   ['$ 5',  '5'],
                   ['$ 10', '10'] ]

    # or all_denoms = Payment::AMOUNT_VALUES
    # although not sure how this works with a hash.

    all_denoms.reject do |current_denom|
      (current_denom - unavailable_denoms).size != 2
    end
  end
  ...
end

<%= f.select :amount, generatePaymentAmountSelectArray(@used_values), {:blank => false}) %>

# just make sure you set @used_values in your controller

I feel like there’s a better way of doing this, so I’ll update if I remember it.