vendor/rails/actionpack/lib/action_view/template_error.rb

   1 module ActionView
   2   # The TemplateError exception is raised when the compilation of the template fails. This exception then gathers a
   3   # bunch of intimate details and uses it to report a very precise exception message.
   4   class TemplateError < ActionViewError #:nodoc:
   5     SOURCE_CODE_RADIUS = 3
   6
   7     attr_reader :original_exception
   8
   9     def initialize(template, assigns, original_exception)
  10       @template, @assigns, @original_exception = template, assigns.dup, original_exception
  11       @backtrace = compute_backtrace
  12     end
  13
  14     def file_name
  15       @template.relative_path
  16     end
  17
  18     def message
  19       ActiveSupport::Deprecation.silence { original_exception.message }
  20     end
  21
  22     def clean_backtrace
  23       if defined?(Rails) && Rails.respond_to?(:backtrace_cleaner)
  24         Rails.backtrace_cleaner.clean(original_exception.backtrace)
  25       else
  26         original_exception.backtrace
  27       end
  28     end
  29
  30     def sub_template_message
  31       if @sub_templates
  32         "Trace of template inclusion: " +
  33         @sub_templates.collect { |template| template.relative_path }.join(", ")
  34       else
  35         ""
  36       end
  37     end
  38
  39     def source_extract(indentation = 0)
  40       return unless num = line_number
  41       num = num.to_i
  42
  43       source_code = @template.source.split("\n")
  44
  45       start_on_line = [ num - SOURCE_CODE_RADIUS - 1, 0 ].max
  46       end_on_line   = [ num + SOURCE_CODE_RADIUS - 1, source_code.length].min
  47
  48       indent = ' ' * indentation
  49       line_counter = start_on_line
  50       return unless source_code = source_code[start_on_line..end_on_line]
  51
  52       source_code.sum do |line|
  53         line_counter += 1
  54         "#{indent}#{line_counter}: #{line}\n"
  55       end
  56     end
  57
  58     def sub_template_of(template_path)
  59       @sub_templates ||= []
  60       @sub_templates << template_path
  61     end
  62
  63     def line_number
  64       @line_number ||=
  65         if file_name
  66           regexp = /#{Regexp.escape File.basename(file_name)}:(\d+)/
  67
  68           $1 if message =~ regexp or clean_backtrace.find { |line| line =~ regexp }
  69         end
  70     end
  71
  72     def to_s
  73       "\n#{self.class} (#{message}) #{source_location}:\n" +
  74       "#{source_extract}\n    #{clean_backtrace.join("\n    ")}\n\n"
  75     end
  76
  77     # don't do anything nontrivial here. Any raised exception from here becomes fatal
  78     # (and can't be rescued).
  79     def backtrace
  80       @backtrace
  81     end
  82
  83     private
  84       def compute_backtrace
  85         [
  86           "#{source_location.capitalize}\n\n#{source_extract(4)}\n    " +
  87           clean_backtrace.join("\n    ")
  88         ]
  89       end
  90
  91       def source_location
  92         if line_number
  93           "on line ##{line_number} of "
  94         else
  95           'in '
  96         end + file_name
  97       end
  98   end
  99 end