parser_json: Make sure return Hash

It is wrong for Parser to return a record that is not Hash.
Subsequent processing may result in errors.

Signed-off-by: Daijiro Fukuda <[email protected]>

lib/fluent/plugin/parser_json.rb

@@ -70,16 +70,33 @@ def configure_json_parser(name)
       end
 
       def parse(text)
-        record = @load_proc.call(text)
-        time = parse_time(record)
-        if @execute_convert_values
-          time, record = convert_values(time, record)
+        parsed_json = @load_proc.call(text)
+
+        if parsed_json.is_a?(Hash)
+          time, record = parse_one_record(parsed_json)
+          yield time, record
+        elsif parsed_json.is_a?(Array)
+          parsed_json.each do |record|
+            unless record.is_a?(Hash)
+              yield nil, nil
+              next
+            end
+            time, parsed_record = parse_one_record(record)
+            yield time, parsed_record
+          end
+        else
+          yield nil, nil
         end
-        yield time, record
+
       rescue @error_class, EncodingError # EncodingError is for oj 3.x or later
         yield nil, nil
       end
 
+      def parse_one_record(record)
+        time = parse_time(record)
+        convert_values(time, record)
+      end
+
       def parser_type
         :text
       end

test/plugin/test_parser_json.rb

@@ -135,4 +135,110 @@ def test_yajl_parse_io_with_buffer_smaller_than_input
       end
     end
   end
+
+  sub_test_case "various record pattern" do
+    data("Only string", { record: '"message"', expected: [nil] }, keep: true)
+    data("Only string without quotation", { record: "message", expected: [nil] }, keep: true)
+    data("Only number", { record: "0", expected: [nil] }, keep: true)
+    data(
+      "Array of Hash",
+      {
+        record: '[{"k1": 1}, {"k2": 2}]',
+        expected: [{"k1" => 1}, {"k2" => 2}]
+      },
+      keep: true,
+    )
+    data(
+      "Array of both Hash and invalid",
+      {
+        record: '[{"k1": 1}, "string", {"k2": 2}, 0]',
+        expected: [{"k1" => 1}, nil, {"k2" => 2}, nil]
+      },
+      keep: true,
+    )
+    data(
+      "Array of all invalid",
+      {
+        record: '["string", 0, [{"k": 0}]]',
+        expected: [nil, nil, nil]
+      },
+      keep: true,
+    )
+
+    def test_oj(data)
+      parsed_records = []
+      @parser.configure("json_parser" => "oj")
+      @parser.instance.parse(data[:record]) { |time, record|
+        parsed_records.append(record)
+      }
+      assert_equal(data[:expected], parsed_records)
+    end
+
+    def test_yajl(data)
+      parsed_records = []
+      @parser.configure("json_parser" => "yajl")
+      @parser.instance.parse(data[:record]) { |time, record|
+        parsed_records.append(record)
+      }
+      assert_equal(data[:expected], parsed_records)
+    end
+
+    def test_json(json)
+      parsed_records = []
+      @parser.configure("json_parser" => "json")
+      @parser.instance.parse(data[:record]) { |time, record|
+        parsed_records.append(record)
+      }
+      assert_equal(data[:expected], parsed_records)
+    end
+  end
+
+  # This becomes NoMethodError if a non-Hash object is passed to convert_values.
+  # https://github.com/fluent/fluentd/issues/4100
+  sub_test_case "execute_convert_values with null_empty_string" do
+    data("Only string", { record: '"message"', expected: [nil] }, keep: true)
+    data(
+      "Hash",
+      {
+        record: '{"k1": 1, "k2": ""}',
+        expected: [{"k1" => 1, "k2" => nil}]
+      },
+      keep: true,
+    )
+    data(
+      "Array of Hash",
+      {
+        record: '[{"k1": 1}, {"k2": ""}]',
+        expected: [{"k1" => 1}, {"k2" => nil}]
+      },
+      keep: true,
+    )
+
+    def test_oj(data)
+      parsed_records = []
+      @parser.configure("json_parser" => "oj", "null_empty_string" => true)
+      @parser.instance.parse(data[:record]) { |time, record|
+        parsed_records.append(record)
+      }
+      assert_equal(data[:expected], parsed_records)
+    end
+
+    def test_yajl(data)
+      parsed_records = []
+      @parser.configure("json_parser" => "yajl", "null_empty_string" => true)
+      @parser.instance.parse(data[:record]) { |time, record|
+        parsed_records.append(record)
+      }
+      assert_equal(data[:expected], parsed_records)
+    end
+
+    def test_json(json)
+      parsed_records = []
+      @parser.configure("json_parser" => "json", "null_empty_string" => true)
+      @parser.instance.parse(data[:record]) { |time, record|
+        parsed_records.append(record)
+      }
+      assert_equal(data[:expected], parsed_records)
+    end
+  end
 end