What Does ActiveRecord::MultiparameterAssignmentErrors Mean?

Question

I have a rails form with a datetime_select field. When I try to submit the form, I get the following exception:

ActiveRecord::MultiparameterAssignmentErrors          


        

Answer 1

Super hack, but I needed to solve this problem right away for a client project. It's still a bug with Rails 2.3.5.

Using either date_select or datetime_select, if you add this to your model in the initialize method, you can pre-parse the passed form-serialized attributes to make it work:

def initialize(attributes={})
  date_hack(attributes, "deliver_date")
  super(attributes)
end

def date_hack(attributes, property)
  keys, values = [], []
  attributes.each_key {|k| keys << k if k =~ /#{property}/ }.sort
  keys.each { |k| values << attributes[k]; attributes.delete(k); }
  attributes[property] = values.join("-")
end

I am using this with a nested, polymorphic, model. Here's a question I had showing the models I'm using. So I needed accepts_nested_attributes_for with a datetime.

Here's the input and output using the console:

e = Event.last
=> #
e.model_surveys
=> []
e.model_surveys_attributes = [{"survey_id"=>"864743981", "deliver_date(1i)"=>"2010", "deliver_date(2i)"=>"2", "deliver_date(3i)"=>"11"}]
PRE ATTRIBUTES: {"survey_id"=>"864743981", "deliver_date(1i)"=>"2010", "deliver_date(2i)"=>"2", "deliver_date(3i)"=>"11"}
# run date_hack
POST ATTRIBUTES: {"survey_id"=>"864743981", "deliver_date"=>"2010-2-11"}
e.model_surveys
=> [#]
>> e.model_surveys.last.deliver_date.class
=> ActiveSupport::TimeWithZone

Otherwise it was either null, or it would throw the error:

1 error(s) on assignment of multiparameter attributes

Hope that helps, Lance