ActiveRecord: find_or_create with has_and_belongs_to_many --

Rails
1

I am attempting to use find_or_create on a foreign table with a
has_and_belongs_to_many relationship with my current table. I am doing
the following:

term = school.terms.find_or_create_by_code(“FALL06”)

the queries in the log show the expected SELECT statement to query if
there is a join table record between the school and term with code
“FALL06”:

SELECT * FROM term
INNER JOIN school_term ON term.id = school_term.term_id
WHERE (school_term.school_id = 1 )
AND (term.code = ‘FALL06’ )
LIMIT 1

but the INSERT behavior does not include a join table insert if the
SELECT does not find an appropriate record:

INSERT INTO term (code, name_full, name_common, date_end,
date_start)
VALUES(‘FALL06’, NULL, NULL, NULL, NULL)

I have resolved this by changing my original code to implement a
uniqueness check in ruby:

term = school.terms.find_or_create_by_code(“FALL06”)
school.terms << term unless school.terms.any? do |i| i == term;

It seems like ActiveRecord and SQL should take care of that behavior
rather than the ActiveRecord implementor and Ruby. Am I missing
something? Is there another way to do what I want?

Also, I’m not sure if c.l.ruby is the best newsgroup, but I couldn’t
find a ruby on rails group.

Thanks Sincerely,
Red Daly

2

I’ve recently used this form:

school.terms << Term.find_or_create_by_code(“FALL06”)