Thursday, March 29, 2012
Hi all,
I have a table where I'm deleting sparse records -- basically cleaning up broken has_many / belongs_to relationships. (How we get into this situation is a trade-off. We can have '000's of records, and deletes generally happening during peak load, so we just do the clean up later.)
I have ModelA and ModelB. ModelB belongs_to ModelA. ModelA has_many ModelB
Anyway, I have figured out the SQL I want (MySQL:
DELETE
model_a_table
FROM
model_a_table
left join model_b_table on model_a_table.model_b_id = model_b_table.id
WHERE
model_b_table.id is NULL;
I believe I have the equivalent SELECT figured out as:
ModelA.includes(:model_b).where(:model_b => {:id => nil})
However, I can't seem to get the equivalent delete working. Adding delete_all to the end of the relationship 'breaks' the includes and causes the where to fail.
I'm going to try and figure this out with the old syntax (ModelA.delete(:conditions...)). Thought I'd ask here first as it seems like I should be able to pretty easily convert the SELECT I have to an equivalent delete operation.
Thanks in advance.
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