Ensuring AR#set_table_name is valid with multiple users

rubyonrails-talk
1

Hi,

due to the legacy nature of my database I have to do a set_table_name() to make sure that the correct MySQL table is picked up by the AR model.

For example:

  model.set_table_name(params[:use_this_table])

One thing that occurred to me is that if I have multiple users accessing my app and they're looking at different tables then I run the risk that one user's set_table_name might over-write another's leading to incorrect data being sent to the user.

To mitigate the problem I do the set_table_name as close as possible to the find() or where I write to the database.

Is this a valid concern? Are there more techniques to prevent this happening or even detect that it happens?

Thanks,

Allan

2

I'd see this as a HUGE design mistake. That is so thread un-safe. Imagine rails being thread-safe in next 6 months, and you'll still be stuck with a big fat lock around your request.

I'm sure there are other ways to achieve whatever it is you're trying to, but this is not a right way. Go with the solution which doesn't change global behavior of your models during request serving.

Probably you might end up having 100 models. Which is just fine.

params[:use_this_model].classify.find(:all) = GOOOOOD model.set_table_name(params[:use_this_table]) && model.find(:all) = BAD/FUGLY