support custom null value

Author: tokibito

README.md

@@ -61,6 +61,7 @@ And you can overwrite default formatting configurations on your plugin (values b
       config_set_default :time_format, nil   # nil means ISO8601 '2012-07-13T19:29:49+09:00'
       config_set_default :remove_prefix, nil
       config_set_default :default_tag, nil
+      config_set_default :null_value, 'NULL'
       
       # ...
     end
@@ -80,13 +81,16 @@ Provided configurations are below:
 * remove_prefix
   * input tag 'test.foo' with 'remove_prefix test', output tag is 'foo'.
   * 'default\_tag' configuration is used when input tag is completely equal to 'remove\_prefix'
+* null_value
+  * output value if value is null(nil). default is 'NULL'.
 
 ## AUTHOR / CONTRIBUTORS
 
 * AUTHOR
   * TAGOMORI Satoshi <[email protected]>
 * CONTRIBUTORS
   * wolfg1969 https://github.com/wolfg1969
+  * Shinya Okano <[email protected]>
 
 ## LICENSE
 

lib/fluent/mixin/plaintextformatter.rb

@@ -7,6 +7,7 @@ module PlainTextFormatter
       attr_accessor :output_include_time, :output_include_tag, :output_data_type
       attr_accessor :add_newline, :field_separator
       attr_accessor :remove_prefix, :default_tag
+      attr_accessor :null_value
 
       attr_accessor :suppress_log_broken_string
 
@@ -46,6 +47,8 @@ def configure(conf)
           end
         end
 
+        @null_value = first_value( conf['null_value'], @null_value, 'NULL' )
+
         # default timezone: utc
         if not conf.has_key?('localtime') and not conf.has_key?('utc')
           @localtime = false
@@ -85,7 +88,7 @@ def stringify_record(record)
           end
         else
           @custom_attributes.map{|attr|
-            record[attr].nil? ? 'NULL' : record[attr].to_s
+            record[attr].nil? ? @null_value : record[attr].to_s
           }.join(@f_separator)
         end
       end

test/mixin/test_plaintextformatter.rb

@@ -289,4 +289,33 @@ def test_format_boolean_attribute
     # format
     assert_equal "2012-07-13T07:05:05Z\ttest.a\ttrue\tfalse\n", p.format('test.a', 1342163105, r)
   end
+
+  def test_null_value_default
+    p = create_plugin_instance(Fluent::TestAOutput, %[
+type testa
+output_include_time false
+output_include_tag false
+output_data_type attr:foo
+])
+    r = {'foo' => nil}
+    # stringify
+    assert_equal "NULL", p.stringify_record(r)
+    # format
+    assert_equal "NULL\n", p.format('test.a', 1342163105, r)
+  end
+
+  def test_null_value_custom
+    p = create_plugin_instance(Fluent::TestAOutput, %[
+type testa
+output_include_time false
+output_include_tag false
+output_data_type attr:foo
+null_value \\N
+])
+    r = {'foo' => nil}
+    # stringify
+    assert_equal "\\N", p.stringify_record(r)
+    # format
+    assert_equal "\\N\n", p.format('test.a', 1342163105, r)
+  end
 end