HABTM Duplication

luislavena · May 13, 2011, 11:06pm

I’m experiencing an issue with duplicate entries being added when using
has_and_belongs_to_many in my models. I’ve setup the following test
Rails
project (v3.0.7) here:

The test case which is failing is:

github.com

mhayes/waterclub/blob/master/test/unit/invoice_test.rb

require 'test_helper'

class InvoiceTest < ActiveSupport::TestCase
  # Replace this with your real tests.
  test "active members should be added on invoice creation" do
    active_count = Member.where(:active => true).count
    i = Invoice.create!(:amount => 34.50, :invoice_date => Date.today)
    assert i.members.count == active_count, "#{i.members.count} members associated with this invoice, expected: #{active_count}"
  end
end

Here’s where I think the issue may reside:

github.com

mhayes/waterclub/blob/master/app/models/invoice.rb

class Invoice < ActiveRecord::Base
    has_many :participations
    has_many :members, :through => :participations
    after_create :add_participants
    
    protected
        def add_participants
          self.members << Member.where(:active => true)
        end
end

I noticed there were threads in the past with a HABTM duplication error,
so
I’m not sure if this is a regression of if I’m doing something wrong.
Any
ideas? Please let me know if I should provide any additional
information,
thanks!

casper_the_ghost · May 13, 2011, 11:27pm

On May 13, 10:05pm, Mark H [email protected] wrote:

I noticed there were threads in the past with a HABTM duplication error, so
I’m not sure if this is a regression of if I’m doing something wrong. Any
ideas? Please let me know if I should provide any additional information,
thanks!

is it because your fixture files define two members that are active
(so they get added to the invoice too) ?

Fred

casper_the_ghost · May 14, 2011, 12:11am

Hey Fred,

Nice catch, I went ahead and updated my fixtures file (so that no active
members are created). However I’m still running into the same issue

casper_the_ghost · May 14, 2011, 8:59pm

Hey Fred,

When attempting to save the members with this newly created invice the
HABTM
relation was trying to add the same member (member_id=1 in my case)
twice.
However I setup a unique index on the composite key (member_id,
invoice_id)
so I end up with a SQLite3 ConstraintError being thrown (which I
expected).

On another note I just changed my code to include a Participation model
that
I’m using to support the many-to-many relationship between Member and
Invoice. Using has_many :members, :through => :participations works
without trying to create duplicate Member entries. So I’m not sure if
this
is an issue with HABTM or my code. Related changes can be found here:

So everything is working as expected now, just a little bit differently
than
I would’ve hoped. Thanks for the tips!

casper_the_ghost · May 14, 2011, 9:54am

On May 13, 11:10pm, Mark H [email protected] wrote:

Hey Fred,

Nice catch, I went ahead and updated my fixtures file (so that no active
members are created). However I’m still running into the same issue

updated fixtures so users are not active by default · mhayes/waterclub@35e985a · GitHub…

So what are the members this newly created invoice has?

Fred