client.rb

# Option 2: Save true or false into the database
# This is the model file
before_save :verify_use_card

def verify_use_card
  if self.use_credit_card == 1
    self.use_credit_card = true  
  else
    self.use_credit_card = false
  end
end

# Implementation in a controller:
@client = Client.find(params[:id])

if @client.use_credit_card
  process_card(@client.card_number)
end

client_helper.rb

# Option 1: Have 0 or 1 saved into the database field.

def use_credit_card?(client_id)
  @client = Client.find(client_id)
  if @client.use_credit_card == 1
    return true
  else
    return false
  end
end

# Implementation:
@client = Client.find(params[:id])

if use_credit_card?(@client.id)
  process_card(@client.card_number)
end

view.html

<input type="checkbox" id="targetMe">
<input type="text" id="client_use_credit_card" name="client[use_credit_card]" value="0" style="display:none;">