JOINS clobbering ids or other fields.

rubyonrails-core
1

I just found this ticket because I noticed the same issue.

http://dev.rubyonrails.org/ticket/6251

The official response was that it's not a bug because when you use :joins you are "riding close to the metal". But I'm at a loss as to figure out why this behavior even needs to exist.

Every table (except HABTM links) in a typical Rails app is going to have an id column, so that means any JOIN by default is going to be clobbering ids. Most of the useful ad-hoc attributes that you would want to add to an query would have to be specified in the :select option anyway... how often do you just want to glom on all the attributes of some other table directly?

A default of SELECT table_name.* in the presence of a :joins option just seems to make sense all around. Is there some benefit to always using SELECT * that warrants using it as the default even when it opens the door for such dangerous and unexpected behavior?

At the very least the documentation for :joins should say "always specify :select or else..."

2

A default of SELECT table_name.* in the presence of a :joins option just seems to make sense all around. Is there some benefit to always using SELECT * that warrants using it as the default even when it opens the door for such dangerous and unexpected behavior?

That sounds like it could be a nice little patch, give it a try and reply here once it's uploaded.

At the very least the documentation for :joins should say "always specify :select or else..."

Agreed, if you can't get the solution above to work, send us a docs patch.

3

Alright, your wish is my command:

http://dev.rubyonrails.org/ticket/8889

The solution is 1.5 lines, and I have a test included. Tested under mysql... not sure if the syntax can be assumed the way I did it for all cases...

4

http://dev.rubyonrails.org/ticket/8889

The solution is 1.5 lines, and I have a test included. Tested under mysql... not sure if the syntax can be assumed the way I did it for all cases...

I've applied the fix because I've also been bitten by this. But we'll have to keep an eye out for surprising breakages in existing apps.

Thanks!

5

Great, thanks. If anything goes wrong I'll definitely be around to add additional test cases and further tweaks if necessary.