fix(logger): enable logging of arbitrary objects

docs/core/logger.md

@@ -298,9 +298,10 @@ If you already have an object containing a `message` key and an additional prope
         logger.info('This is a log with an extra variable', { data: myImportantVariable });
 
         // You can also pass multiple parameters
-        logger.info('This is a log with 2 extra variables',
+        logger.info('This is a log with 3 extra objects',
             { data: myImportantVariable },
-            { correlationIds: { myCustomCorrelationId: 'foo-bar-baz' } }
+            { correlationIds: { myCustomCorrelationId: 'foo-bar-baz' } },
+            { lambdaEvent: _event }
         );
 
         // Simply pass a string for logging additional data

packages/logger/examples/additional-keys.ts

@@ -12,7 +12,7 @@ import { Logger } from '../src';
 
 const logger = new Logger();
 
-const lambdaHandler: Handler = async () => {
+const lambdaHandler: Handler = async (event) => {
 
   // Pass a custom correlation ID
   logger.warn('This is a WARN log', { correlationIds: { myCustomCorrelationId: 'foo-bar-baz' } });
@@ -23,6 +23,9 @@ const lambdaHandler: Handler = async () => {
   // Pass a simple string as additional data
   logger.info('This is an INFO log', 'Extra log data');
 
+  // Pass an arbitrary object as additional data
+  logger.debug('This is a DEBUG log', { lambdaEvent: event });
+
   return {
     foo: 'bar'
   };

packages/logger/src/types/Log.ts

@@ -9,7 +9,7 @@ type LogLevelThresholds = {
   [key in LogLevel]: number;
 };
 
-type LogAttributeValue = string | number | boolean | null | undefined | LogAttributeValue[] | { [key: string]: LogAttributeValue } | Error;
+type LogAttributeValue = unknown;
 type LogAttributes = { [key: string]: LogAttributeValue };
 
 type LogAttributesWithMessage = LogAttributes & {

packages/logger/tests/unit/Logger.test.ts

@@ -280,6 +280,9 @@ describe('Class: Logger', () => {
           });
           const consoleSpy = jest.spyOn(logger['console'], methodOfLogger).mockImplementation();
 
+          interface ArbitraryObject { value: 'CUSTOM' | 'USER_DEFINED' }
+          const arbitraryObject: ArbitraryObject = { value: 'CUSTOM' };
+
           // Act
           if (logger[methodOfLogger]) {
             logger[methodOfLogger]('A log item without extra parameters');
@@ -289,6 +292,8 @@ describe('Class: Logger', () => {
             logger[methodOfLogger]('A log item with a string as first parameter, and an error as second parameter', new Error('Something happened!'));
             logger[methodOfLogger]('A log item with a string as first parameter, and an error with custom key as second parameter', { myCustomErrorKey: new Error('Something happened!') });
             logger[methodOfLogger]('A log item with a string as first parameter, and a string as second parameter', 'parameter');
+            logger[methodOfLogger]('A log item with a string as first parameter, and an inline object as second parameter', { extra: { custom: mockDate } });
+            logger[methodOfLogger]('A log item with a string as first parameter, and an arbitrary object as second parameter', { extra: arbitraryObject });
           }
 
           // Assess
@@ -360,6 +365,22 @@ describe('Class: Logger', () => {
             xray_trace_id: '1-5759e988-bd862e3fe1be46a994272793',
             extra: 'parameter',
           }));
+          expect(consoleSpy).toHaveBeenNthCalledWith(8, JSON.stringify({
+            level: method.toUpperCase(),
+            message: 'A log item with a string as first parameter, and an inline object as second parameter',
+            service: 'hello-world',
+            timestamp: '2016-06-20T12:08:10.000Z',
+            xray_trace_id: '1-5759e988-bd862e3fe1be46a994272793',
+            extra: { custom: '2016-06-20T12:08:10.000Z' }
+          }));
+          expect(consoleSpy).toHaveBeenNthCalledWith(9, JSON.stringify({
+            level: method.toUpperCase(),
+            message: 'A log item with a string as first parameter, and an arbitrary object as second parameter',
+            service: 'hello-world',
+            timestamp: '2016-06-20T12:08:10.000Z',
+            xray_trace_id: '1-5759e988-bd862e3fe1be46a994272793',
+            extra: { value: 'CUSTOM' }
+          }));
         });
       });