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       original_exception.clean_backtrace
  24     end
  25
  26     def sub_template_message
  27       if @sub_templates
  28         "Trace of template inclusion: " +
  29         @sub_templates.collect { |template| template.relative_path }.join(", ")
  30       else
  31         ""
  32       end
  33     end
  34
  35     def source_extract(indentation = 0)
  36       return unless num = line_number
  37       num = num.to_i
  38
  39       source_code = @template.source.split("\n")
  40
  41       start_on_line = [ num - SOURCE_CODE_RADIUS - 1, 0 ].max
  42       end_on_line   = [ num + SOURCE_CODE_RADIUS - 1, source_code.length].min
  43
  44       indent = ' ' * indentation
  45       line_counter = start_on_line
  46       return unless source_code = source_code[start_on_line..end_on_line]
  47
  48       source_code.sum do |line|
  49         line_counter += 1
  50         "#{indent}#{line_counter}: #{line}\n"
  51       end
  52     end
  53
  54     def sub_template_of(template_path)
  55       @sub_templates ||= []
  56       @sub_templates << template_path
  57     end
  58
  59     def line_number
  60       @line_number ||=
  61         if file_name
  62           regexp = /#{Regexp.escape File.basename(file_name)}:(\d+)/
  63
  64           $1 if message =~ regexp or clean_backtrace.find { |line| line =~ regexp }
  65         end
  66     end
  67
  68     def to_s
  69       "\n\n#{self.class} (#{message}) #{source_location}:\n" +
  70         "#{source_extract}\n    #{clean_backtrace.join("\n    ")}\n\n"
  71     end
  72
  73     # don't do anything nontrivial here. Any raised exception from here becomes fatal
  74     # (and can't be rescued).
  75     def backtrace
  76       @backtrace
  77     end
  78
  79     private
  80       def compute_backtrace
  81         [
  82           "#{source_location.capitalize}\n\n#{source_extract(4)}\n    " +
  83           clean_backtrace.join("\n    ")
  84         ]
  85       end
  86
  87       def source_location
  88         if line_number
  89           "on line ##{line_number} of "
  90         else
  91           'in '
  92         end + file_name
  93       end
  94   end
  95 end
  96
  97 if defined?(Exception::TraceSubstitutions)
  98   Exception::TraceSubstitutions << [/:in\s+`_run_.*'\s*$/, '']
  99   Exception::TraceSubstitutions << [%r{^\s*#{Regexp.escape RAILS_ROOT}/}, ''] if defined?(RAILS_ROOT)
 100 end