Merge pull request #10 from daichirata/reject-empty-keys

Drop empty-key pairs in query_string_parser

Author: daichirata

README.md

@@ -150,6 +150,8 @@ When a component is missing (no query, no fragment, etc.) the default is to emit
 
 Decomposes a query string field into individual parameters.
 
+> Pairs with an empty key (e.g. the leading `&` in `&foo=1`) are silently dropped — they're noise from user-supplied URLs and never represent a real parameter.
+
 ### Minimal example
 
 ```aconf

lib/fluent/plugin/filter_query_string_parser.rb

@@ -27,6 +27,7 @@ def filter(tag, time, record)
 
         begin
           params = Addressable::URI.form_unencode(raw_value)
+          params = params.reject {|k, _| k.nil? || k.empty? }
 
           unless params.empty?
             if @multi_value_params

test/plugin/test_filter_query_string_parser.rb

@@ -30,6 +30,29 @@ def test_filter
     assert_equal "fuga",              records[0]["hoge"]
   end
 
+  def test_filter_drops_empty_keys
+    config = %[
+      key_name query
+      hash_value_field parsed
+    ]
+
+    d1 = create_driver(config)
+    d1.run(default_tag: @tag) do
+      d1.feed(@time, { "query" => "&partnerid=12345" })
+      d1.feed(@time, { "query" => "=value&foo=bar" })
+      d1.feed(@time, { "query" => "&&foo=bar&&" })
+      d1.feed(@time, { "query" => "foo=&bar=baz" })
+    end
+    records = d1.filtered_records
+
+    assert_equal 4, records.length
+
+    assert_equal({ "partnerid" => "12345" }, records[0]["parsed"])
+    assert_equal({ "foo" => "bar" },         records[1]["parsed"])
+    assert_equal({ "foo" => "bar" },         records[2]["parsed"])
+    assert_equal({ "foo" => "", "bar" => "baz" }, records[3]["parsed"])
+  end
+
   def test_filter_non_ascii
     config = %[
       key_name query