Davis W. Frank's blog
Interesting Things
find_in_batches has Evil Scopiness
ActiveRecord::Base#find_in_batches() (and therefore #find_each()) is applying a scope around the block it is given, which applies to any subsequent find call on that model:
Let's say we have a Comment model that act_as_tree so comments can be threaded. In the following code:
Comment.find_each(:conditions => "comments.state = 'published'") do |comment|
puts comment.parent.content
end
The association call to .parent will also have the scope {:conditions => "comments.state = 'published'"} applied to it. This can have highly unexpected side-effects.
The way to get around this is:
Comment.find_each(:conditions => "comments.state = 'published'") do |comment|
Comment.with_exclusive_scope(:find => {}) do
puts comment.parent.content
end
end
Easy Ruby profiling
If you're profiling Ruby code often, here's a code snippet that can be useful: