Has_many relationships

In my model I have two classes, a donation class and a good class. A
donation can have mulitple goods, so I set up a has_many relationship
between the two objects.

class Donation < ActiveRecord::Base
has_many :goods

class Good < ActiveRecord::Base
belongs_to :donation

In my view (donation/new.html.erb), I add goods to a donation the
following way;

This will create the following @params after submitting the form.

“description”=>“Children books”},
“description”=>“Leather Boots”},
“description”=>“wool blankets”},}}}

The donation controller:

class DonationsController < ApplicationController
def create
@donation = Donation.new(params[:donation])

So, I was hoping that ruby on rails automatically generates the goods
and adds them to the donation object, but when create is called, i get
the following error on the first line;

ActiveRecord::AssociationTypeMismatch in DonationsController#create

Good expected, got Array

Any help is appreciated.

Thanks. Is there some way to manipulate the @params info so that ruby
automates this process?

On Jan 29, 1:21 pm, Chris O. [email protected]

There is a lot of magic in rails, but not that much.

Based on the @params info that you showed you will have to extract the
donation info, create the object and manually make the relations to the

def create
@donation = Donation.new(params[:donation])
params[:donation][:goods].each do |g|

if @donation.save


Or something like that.

Franz Obenhauser wrote:

Thanks. Is there some way to manipulate the @params info so that ruby
automates this process?

On Jan 29, 1:21 pm, Chris O. [email protected]

I think I could explain this if I had to, but let me send you someplace
better first and if that doesn’t help come back. Railscasts had three
excelent screen casts on doing exactly what your asking about, and they
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