HABTM Duplication

rubyonrails-talk
1

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:

https://github.com/mhayes/waterclub

The test case which is failing is: https://github.com/mhayes/waterclub/blob/master/test/unit/invoice_test.rb

Here’s where I think the issue may reside: https://github.com/mhayes/waterclub/blob/master/app/models/invoice.rb

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!

2

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

Fred

3

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 :frowning:

https://github.com/mhayes/waterclub/commit/35e985ab5e09f6c40b576991838f901cc5e5247d

4

So what are the members this newly created invoice has?

Fred

5

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:

https://github.com/mhayes/waterclub/commit/ef74f18a62dcfa65cb009f64f96c62a99115a569

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