Allow email_prefix to be a proc

README.md

@@ -182,9 +182,9 @@ Who the message is destined for, can be a string of addresses, an array of addre
 
 ##### email_prefix
 
-*String, default: [ERROR]*
+*String/Proc, default: [ERROR]*
 
-The subject's prefix of the message.
+The subject's prefix of the message. It can be a proc that returns a string. The proc will be evaluated when the mail is sent.
 
 ##### sections
 

lib/exception_notifier/email_notifier.rb

@@ -20,6 +20,8 @@ def method_missing(*args, &block)
 
  def self.extended(base)
  base.class_eval do
+ attr_reader :env, :exception, :request, :data
+
  self.send(:include, ExceptionNotifier::BacktraceCleaner)
 
  # Append application view path to the ExceptionNotifier lookup context.
@@ -59,7 +61,7 @@ def background_exception_notification(exception, options={}, default_options={})
  private
 
  def compose_subject
- subject = "#{@options[:email_prefix]}"
+ subject = "#{maybe_call(@options[:email_prefix])}"
  subject << "(#{@options[:accumulated_errors_count]} times)" if @options[:accumulated_errors_count].to_i > 1
  subject << "#{@kontroller.controller_name} #{@kontroller.action_name}" if @kontroller && @options[:include_controller_and_action_names_in_subject]
  subject << " (#{@exception.class})"
@@ -130,7 +132,8 @@ def load_custom_views
  end
 
  def maybe_call(maybe_proc)
- maybe_proc.respond_to?(:call) ? maybe_proc.call : maybe_proc
+ return maybe_proc unless maybe_proc.respond_to?(:call)
+ (maybe_proc.arity == 0) ? maybe_proc.call : maybe_proc.call(self)
  end
  end
  end

test/exception_notifier/email_notifier_test.rb

@@ -219,6 +219,21 @@ class EmailNotifierTest < ActiveSupport::TestCase
  assert_equal %w{[email protected]}, mail.to
  end
 
+ test "should lazily evaluate email_prefix" do
+ email_prefixes = %w(first second)
+ email_notifier = ExceptionNotifier::EmailNotifier.new(
+ :email_prefix => -> { email_prefixes.shift },
+ :sender_address => %{"Dummy Notifier" <[email protected]>},
+ :exception_recipients => "[email protected]",
+ :delivery_method => :test,
+ )
+
+ mail = email_notifier.call(@exception)
+ assert_equal %|first (ZeroDivisionError) "divided by 0"|, mail.subject
+ mail = email_notifier.call(@exception)
+ assert_equal %|second (ZeroDivisionError) "divided by 0"|, mail.subject
+ end
+
  test "should prepend accumulated_errors_count in email subject if accumulated_errors_count larger than 1" do
  ActionMailer::Base.deliveries.clear