Issue #19197 has been updated by Eregon (Benoit Daloze). I think more complex cases like `causes` should be done manually or with a helper method, like you showed or with some loop or something. OTOH I think `root_cause` is convenient and useful for a variety of cases, so it makes more sense to be in core. ---------------------------------------- Feature #19197: Add Exception#root_cause https://bugs.ruby-lang.org/issues/19197#change-101871 * Author: AMomchilov (Alexander Momchilov) * Status: Open * Priority: Normal ---------------------------------------- ### Description I would like to add a `#root_cause` method to `Exception`. It returns the last exception in linked-list of causality chain, that is, the original exception (whose own `cause` is `nil`). ### Example ```ruby e = begin raise 'A' # This is the root cause rescue => a begin raise 'B' rescue => B begin raise 'C' # This is the outermost cause assigned to `e` rescue => c c end end end # Here's what the structure looks like: # C -> B -> A -> nil p(e) # => #<RuntimeError: C> p(e.cause) # => #<RuntimeError: B> p(e.cause.cause) # => #<RuntimeError: A> p(e.cause.cause.cause) # => nil # Here's the proposed API, showing that A is the root cause of e p(e.root_cause) # => #<RuntimeError: A> # And that the root_cause has no further cause p(e.root_cause.cause) # => nil ``` ### Motivation There are some kinds of exceptions that can occur all over the place (and might be wrapped by arbitrarily many middlemen), but are attributable to a singular global cause. For example, a database outage could raise exceptions in almost every line of business logic of an app that uses ActiveRecord models. Fundamentally, you wouldn't want an error report for every one of these lines. You'd want to look at the root cause, and bucket all SQL-connection issues into a single report, regardless of where they surface. ### Implementation Draft PR: https://github.com/ruby/ruby/pull/6913 -- https://bugs.ruby-lang.org/