Many backtraces include too much information that’s not relevant for the context. This makes it hard to find the signal in the backtrace and adds debugging time. With a BacktraceCleaner, you can setup filters and silencers for your particular context, so only the relevant lines are included.
If you need to reconfigure an existing BacktraceCleaner, like the one in Rails, to show as much as possible, you can always call #remove_silencers! Also, if you need to reconfigure an existing BacktraceCleaner so that it does not filter or modify the paths of any lines of the backtrace, you can call #remove_filters! These two methods will give you a completely untouched backtrace.
Example:
bc = BacktraceCleaner.new bc.add_filter { |line| line.gsub(Rails.root, '') } bc.add_silencer { |line| line =~ %rmongrel|rubygems/ } bc.clean(exception.backtrace) # will strip the Rails.root prefix and skip any lines from mongrel or rubygems
Inspired by the Quiet Backtrace gem by Thoughtbot.
Adds a filter from the block provided. Each line in the backtrace will be mapped against this filter.
Example:
# Will turn "/my/rails/root/app/models/person.rb" into "/app/models/person.rb" backtrace_cleaner.add_filter { |line| line.gsub(Rails.root, '') }
# File lib/active_support/backtrace_cleaner.rb, line 44 def add_filter(&block) @filters << block end
Adds a silencer from the block provided. If the silencer returns true for a given line, it’ll be excluded from the clean backtrace.
Example:
# Will reject all lines that include the word "mongrel", like "/gems/mongrel/server.rb" or "/app/my_mongrel_server/rb" backtrace_cleaner.add_silencer { |line| line =~ %rmongrel/ }
# File lib/active_support/backtrace_cleaner.rb, line 55 def add_silencer(&block) @silencers << block end
Returns the backtrace after all filters and silencers has been run against it. Filters run first, then silencers.
# File lib/active_support/backtrace_cleaner.rb, line 25 def clean(backtrace, kind = :silent) filtered = filter(backtrace) case kind when :silent silence(filtered) when :noise noise(filtered) else filtered end end
# File lib/active_support/backtrace_cleaner.rb, line 65 def remove_filters! @filters = [] end
Will remove all silencers, but leave in the filters. This is useful if your context of debugging suddenly expands as you suspect a bug in the libraries you use.
# File lib/active_support/backtrace_cleaner.rb, line 61 def remove_silencers! @silencers = [] end
# File lib/active_support/backtrace_cleaner.rb, line 20 def initialize @filters, @silencers = [], [] end