Class: Utopia::Exceptions::Handler

Inherits:
Object
  • Object
show all
Defined in:
lib/utopia/exceptions/handler.rb

Overview

Catches exceptions and performs an internal redirect.

Instance Method Summary collapse

Constructor Details

#initialize(app, location = '/errors/exception') ⇒ Handler

Returns a new instance of Handler.



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# File 'lib/utopia/exceptions/handler.rb', line 25

def initialize(app, location = '/errors/exception')
  @app = app
  
  @location = location
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/utopia/exceptions/handler.rb', line 53

def call(env)
  begin
    return @app.call(env)
  rescue Exception => exception
    log_exception(env, exception)
    
    # If the error occurred while accessing the error handler, we finish with a fatal error:
    if env[Rack::PATH_INFO] == @location
      return fatal_error(env, exception)
    else
      begin
        # We do an internal redirection to the error location:
        error_request = env.merge(Rack::PATH_INFO => @location, Rack::REQUEST_METHOD => Rack::GET)
        error_response = @app.call(error_request)
        
        return [500, error_response[1], error_response[2]]
      rescue Exception
        # If redirection fails, we also finish with a fatal error:
        return fatal_error(env, exception)
      end
    end
  end
end

#fatal_error(env, exception) ⇒ Object

Generate a very simple fatal error response. This function should be unlikely to fail. Additionally, it generates a lowest common denominator response which should be suitable as a response to any kind of request. Ideally, this response is also not good or useful for any kind of higher level browser or API client, as this is not a normal error path but one that represents broken behaviour.



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# File 'lib/utopia/exceptions/handler.rb', line 38

def fatal_error(env, exception)
  body = StringIO.new
  
  write_exception_to_stream(body, env, exception)
  body.rewind
  
  return [500, {HTTP::CONTENT_TYPE => "text/plain"}, body]
end

#freeze ⇒ Object 



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# File 'lib/utopia/exceptions/handler.rb', line 31

def freeze
  @location.freeze
  
  super
end

#log_exception(env, exception) ⇒ Object 



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# File 'lib/utopia/exceptions/handler.rb', line 47

def log_exception(env, exception)
  # An error has occurred, log it:
  output = env['rack.errors'] || $stderr
  write_exception_to_stream(output, env, exception, true)
end