Question

I have a model Foo and a model Bar, both of which has_many :bar_foos (and then has_many each other :through => :bar_foos). It’s a simple many:many relationship between Foo and Bar, through a BarsFoo model.

I want to delete several rows in the bar_foos table. Specifically, I want to delete any bar_foo record that relates to any of a given set of Foos and any of a given set of Bars. For performance, I’d like to issue a single database call to do this.

The corresponding SQL statement would be:

DELETE FROM bar_foos WHERE bar_id IN ( ?, ?, ? ) AND foo_id in ( ?, ?, ? )

…while replacing the ?s with the appropriate IDs.

How do I perform this using Rails 2.3.x?

Ideally, I’d to not write the actual SQL myself, but make ActiveRecord method calls instead. However, I doubt this exists.

Barring that, I’ll craft the SQL statement myself, but:

• I’d like to avoid hardcoding the table/column names in the SQL string
• I’d like to use some sort of automatic (ie: reliable) method to escape the SQL parameters vs. just concatenating strings.

Answer 1

I think it’s not possible using assosciation you have to write it your own (Use destroy_all)

BarFoo.destroy_all(["bar_id IN (?) AND foo_id in (?)", bar_id_array, foo_id_array])