Json formatter should always format context/extra as an object, fixes #1028

src/Monolog/Formatter/JsonFormatter.php

@@ -64,7 +64,15 @@ class JsonFormatter extends NormalizerFormatter
      */
     public function format(array $record): string
     {
-        return $this->toJson($this->normalize($record), true) . ($this->appendNewline ? "\n" : '');
+        $normalized = $this->normalize($record);
+        if (isset($normalized['context']) && $normalized['context'] === []) {
+            $normalized['context'] = new \stdClass;
+        }
+        if (isset($normalized['extra']) && $normalized['extra'] === []) {
+            $normalized['extra'] = new \stdClass;
+        }
+
+        return $this->toJson($normalized, true) . ($this->appendNewline ? "\n" : '');
     }
 
     /**

tests/Monolog/Formatter/JsonFormatterTest.php

@@ -38,11 +38,12 @@ class JsonFormatterTest extends TestCase
     {
         $formatter = new JsonFormatter();
         $record = $this->getRecord();
+        $record['context'] = $record['extra'] = new \stdClass;
         $this->assertEquals(json_encode($record)."\n", $formatter->format($record));
 
         $formatter = new JsonFormatter(JsonFormatter::BATCH_MODE_JSON, false);
         $record = $this->getRecord();
-        $this->assertEquals('{"message":"test","context":[],"level":300,"level_name":"WARNING","channel":"test","datetime":"'.$record['datetime']->format('Y-m-d\TH:i:s.uP').'","extra":[]}', $formatter->format($record));
+        $this->assertEquals('{"message":"test","context":{},"level":300,"level_name":"WARNING","channel":"test","datetime":"'.$record['datetime']->format('Y-m-d\TH:i:s.uP').'","extra":{}}', $formatter->format($record));
     }
 
     /**
@@ -71,6 +72,7 @@ class JsonFormatterTest extends TestCase
             $this->getRecord(Logger::DEBUG),
         ];
         array_walk($expected, function (&$value, $key) {
+            $value['context'] = $value['extra'] = new \stdClass;
             $value = json_encode($value);
         });
         $this->assertEquals(implode("\n", $expected), $formatter->formatBatch($records));
@@ -160,7 +162,7 @@ class JsonFormatterTest extends TestCase
     private function assertContextContainsFormattedException($expected, $actual)
     {
         $this->assertEquals(
-            '{"level_name":"CRITICAL","channel":"core","context":{"exception":'.$expected.'},"datetime":null,"extra":[],"message":"foobar"}'."\n",
+            '{"level_name":"CRITICAL","channel":"core","context":{"exception":'.$expected.'},"datetime":null,"extra":{},"message":"foobar"}'."\n",
             $actual
         );
     }

tests/Monolog/Handler/LogmaticHandlerTest.php

@@ -37,7 +37,7 @@ class LogmaticHandlerTest extends TestCase
         fseek($this->res, 0);
         $content = fread($this->res, 1024);
 
-        $this->assertRegexp('/testToken {"message":"Critical write test","context":\[\],"level":500,"level_name":"CRITICAL","channel":"test","datetime":"(.*)","extra":\[\],"hostname":"testHostname","appname":"testAppname","@marker":\["sourcecode","php"\]}/', $content);
+        $this->assertRegexp('/testToken {"message":"Critical write test","context":{},"level":500,"level_name":"CRITICAL","channel":"test","datetime":"(.*)","extra":{},"hostname":"testHostname","appname":"testAppname","@marker":\["sourcecode","php"\]}/', $content);
     }
 
     public function testWriteBatchContent()
@@ -53,7 +53,7 @@ class LogmaticHandlerTest extends TestCase
         fseek($this->res, 0);
         $content = fread($this->res, 1024);
 
-        $this->assertRegexp('/testToken {"message":"test","context":\[\],"level":300,"level_name":"WARNING","channel":"test","datetime":"(.*)","extra":\[\],"hostname":"testHostname","appname":"testAppname","@marker":\["sourcecode","php"\]}/', $content);
+        $this->assertRegexp('/testToken {"message":"test","context":{},"level":300,"level_name":"WARNING","channel":"test","datetime":"(.*)","extra":{},"hostname":"testHostname","appname":"testAppname","@marker":\["sourcecode","php"\]}/', $content);
     }
 
     private function createHandler()