Omitempty

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 3.5.1
+ - feature: Added 'omitempty' feature to remove fields with default or null values
+
 ## 3.4.0
  - Added ability to directly convert from integer and float to boolean [#127](https://github.com/logstash-plugins/logstash-filter-mutate/pull/127)
 

CONTRIBUTORS

@@ -25,6 +25,7 @@ Contributors:
 * Tal Levy (talevy)
 * piavlo
 * Abdul Haseeb Hussain (AbdulHaseebHussain)
+* Gregory Ferreux (gferreux)
 
 Note: If you've sent us patches, bug reports, or otherwise contributed to
 Logstash, and you aren't on the list above and want to be, please let us know

lib/logstash/filters/mutate.rb

@@ -207,6 +207,17 @@ class LogStash::Filters::Mutate < LogStash::Filters::Base
   #     }
   config :copy, :validate => :hash
 
+  # Omit a variable if it as a default value.
+  #
+  # Example:
+  # [source,ruby]
+  #     filter {
+  #       mutate {
+  #         omitempty => [ "fieldname" ]
+  #       }
+  #     }
+  config :omitempty, :validate => :array
+
   # Tag to apply if the operation errors
   config :tag_on_failure, :validate => :string, :default => '_mutate_error'
 
@@ -263,6 +274,7 @@ def filter(event)
     join(event) if @join
     merge(event) if @merge
     copy(event) if @copy
+    omitempty(event) if @omitempty
 
     filter_matched(event)
   rescue => ex
@@ -474,6 +486,26 @@ def capitalize(event)
     end
   end
 
+  def omitempty(event)
+    @omitempty.each do |field|
+      original = event.get(field)
+      if original.nil?
+        event.remove(field)
+        next
+      end
+      result = case original
+               when String, Array, Hash
+                 original.empty? ? nil : original
+               when Integer
+                 original == 0 ? nil : original
+               else
+                 @logger.debug? && @logger.debug("Can't omitempty something that isn't a string,array,hash,integer", :field => field, :value => original)
+                 original
+               end
+      event.remove(field) if result.nil?
+    end
+  end
+
   def split(event)
     @split.each do |field, separator|
       value = event.get(field)

logstash-filter-mutate.gemspec

@@ -1,7 +1,7 @@
 Gem::Specification.new do |s|
 
   s.name            = 'logstash-filter-mutate'
-  s.version         = '3.5.0'
+  s.version         = '3.5.1'
   s.licenses        = ['Apache License (2.0)']
   s.summary         = "Performs mutations on fields"
   s.description     = "This gem is a Logstash plugin required to be installed on top of the Logstash core pipeline using $LS_HOME/bin/logstash-plugin install gemname. This gem is not a stand-alone program"

spec/filters/mutate_spec.rb

@@ -1088,4 +1088,45 @@ def pattern_path(path)
     end
   end
 
+  describe "omitempty" do
+
+    config <<-CONFIG
+      filter {
+        mutate {
+          omitempty => ["field"]
+        }
+      }
+    CONFIG
+
+    context 'when field is a string' do
+      sample({'field' => ''}) do
+        expect(subject).not_to include("field")
+      end
+    end
+
+    context 'when field is an integer' do
+      sample({'field' => 0}) do
+        expect(subject).not_to include("field")
+      end
+    end
+
+    context 'when field is an empty hash' do
+      sample({'field' => {}}) do
+        expect(subject).not_to include("field")
+      end
+    end
+
+    context 'when field is an empty array' do
+      sample({'field' => []}) do
+        expect(subject).not_to include("field")
+      end
+    end
+
+    context 'when field is null' do
+      sample({'field' => nil}) do
+        expect(subject).not_to include("field")
+      end
+    end
+  end
+
 end