1 error(s) on assignment of multiparameter attributes

I am trying to create a form for processing credit cards. For the
credit card expiration date, I would like to leave the day field out
of the form for obvious reasons. However, the following code is
producing an error for me.

Any ideas?


<p><label for="email">Expiration</label><br/>
<input type="hidden" id="user_card_expiration_3i"
name="user[card_expiration(3i)]" value="1" />
<%= f.date_select(:card_expiration, :start_year =>
2008, :use_month_numbers => false,
                                    :discard_day =>
true, :include_blank => false) %></p>

ActiveRecord::MultiparameterAssignmentErrors in


"commit"=>"Sign up",

How about leaving the date field out altogether? Passing in just a month and a year should do the trick.

Makes sense, i could even make it one single drop down. How would i have the default selection be this years current month tho?

I was able to get rid of the error by converting the column to a Date Type instead of a String type.