Class: ActiveSupport::BacktraceCleaner

Inherits:
Object
  • Object
show all
Defined in:
activesupport/lib/active_support/backtrace_cleaner.rb

Overview

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 BacktraceCleaner#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 BacktraceCleaner#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 =~ /mongrel|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.

Instance Method Summary (collapse)

Constructor Details

- (BacktraceCleaner) initialize

A new instance of BacktraceCleaner



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# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 20

def initialize
  @filters, @silencers = [], []
end

Instance Method Details

- (Object) add_filter(&block)

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, '') }


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# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 44

def add_filter(&block)
  @filters << block
end

- (Object) add_silencer(&block)

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 =~ /mongrel/ }


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# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 55

def add_silencer(&block)
  @silencers << block
end

- (Object) clean(backtrace, kind = :silent)

Returns the backtrace after all filters and silencers has been run against it. Filters run first, then silencers.



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# File 'activesupport/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

- (Object) remove_filters! 



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# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 65

def remove_filters!
  @filters = []
end

- (Object) remove_silencers!

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.



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# File 'activesupport/lib/active_support/backtrace_cleaner.rb', line 61

def remove_silencers!
  @silencers = []
end