ActiveRecord destroy has_many :through record from relational table

Question

Logistic & Rental Requests belong to each other via a TypeLogistic table. I accidentally created a bad TypeLogistic, so now there are two:

TypeLogistic.where(rental_request_id:200).where(logistic_id:130)
=> #<ActiveRecord::Relation [#<TypeLogistic rental_request_id: 200, logistic_id: 130, type_of_logistics: nil>, #<TypeLogistic rental_request_id: 200, logistic_id: 130, type_of_logistics: "delivery">]>

How do I destroy the first one? Tried running below, didn't work

TypeLogistic.where(rental_request_id:200).where(logistic_id:130).first.destroy
PG::Error: ERROR:  zero-length delimited identifier at or near """"
LINE 1: DELETE FROM "type_logistics" WHERE "type_logistics"."" = $1
                                                            ^

Why not just `TypeLogistic.find_by(rental_request_id: 200).destroy`? — max, Oct 08 '15 at 23:07
Hmm, this looks like a AREL bug unless there is something really weird going on with your schema. — max, Oct 09 '15 at 00:50
so... i'm screwed? are there potentially other ways of fixing this? — james, Oct 09 '15 at 04:26

score 2 · Accepted Answer · edited May 23 '17 at 10:27

2

The error is being thrown because the TypeLogistic join table does not have a primary key. Incidentally, this is the default setting it appears, since I followed the instructions to create the join table without altering anything.

Detailed info here: Rails Devise PG::SyntaxError: ERROR: zero-length delimited identifier at or near """"

Solution? Add a primary key, see this answer below:

Add Id column in a migration

edited May 23 '17 at 10:27

Community

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answered Oct 09 '15 at 07:10

james

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Worth noting that this can also happen if you add to a relation for a join table, which I just ran into. e.g. if you have Book, Author, and a joining model called BookAuthor, on Author you'd have `has_many :book_authors` and then a has_many :through for the relationship to the books. If you have `has_many :book_authors, dependent: :destroy`, that's wrong and the dependent destroy shouldn't be on the has_many that associates to the joining model. – Connor Shea Jun 15 '21 at 22:01

ActiveRecord destroy has_many :through record from relational table

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