In the docs, there is an example of using lambdas with the store_in macro:

class Band
include Mongoid::Document
store_in database: ->

end

However, it does not work as expected:

Thread.current[:database] = 'first'
Band.database_name #=> :first
Thread.current[:database] = 'second'
Band.database_name #=> :first (when :second is expected)

I believe this is because #database_name memoizes the name when it is called for the first time.

Same thing happens for #collection_name as well.