Data field different format

.gitignore

@@ -1 +1,2 @@
 /node_modules/
+.idea

lib/index.js

@@ -32,15 +32,22 @@ function fluentAppender(config, layout) {
   const logSender = FluentSender.createFluentSender(tag_prefix, options);
 
   const appender = function(loggingEvent) {
-    const data =  util.format.apply(null, loggingEvent.data);
-    const rec = {
+    const data =  loggingEvent.data[0];
+    const extra = loggingEvent.data.splice(1);
+
+    let rec = {
       timestamp: loggingEvent.startTime.getTime(),
       category: loggingEvent.categoryName,
       levelInt: loggingEvent.level.level,
       levelStr: loggingEvent.level.levelStr,
       context: loggingEvent.context,
       data: data
     };
+
+    if (extra.length) {
+      rec['extra'] = Object.assign(...extra);
+    }
+
     if (options.levelTag !== false) {
       logSender.emit(loggingEvent.level.levelStr, rec);
     } else {

test/test.log4js.js

@@ -118,4 +118,37 @@ describe('log4js-fluent-appender', () => {
     done();
   });
 
+  it('should log extra', (done) => {
+    const tag_prefix = 'tag_prefix';
+    const options = {
+      levelTag: false,
+      host: 'localhost',
+      port: 24224
+    };
+    const fakeSender = {
+      emit: td.function()
+    };
+    td
+      .when(fluentLogger.createFluentSender(tag_prefix, options))
+      .thenReturn(fakeSender);
+    const logger = getLogger(tag_prefix, options);
+
+    logger.info('This is info message!', {extra1: true, extra2: false}, {extra3: true});
+
+    td.verify(fakeSender.emit({
+      timestamp: td.matchers.anything(),
+      category: 'default',
+      levelInt: 20000,
+      levelStr: 'INFO',
+      context: {},
+      data: 'This is info message!',
+      extra: {
+        extra1: true,
+        extra2: false,
+        extra3: true,
+      }
+    }));
+    done();
+  });
+
 });