fix(gcp): allow logging message as jsonPayload (#393)

Closes #394

Author: felangel

gcp/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.1.2-wip
+
+- `cloudLoggingMiddleware` uses structured logs (`jsonPayload`) when message is of type `Map`. All other messages are logged as text (`textPayload`).
+
 ## 0.1.1
 
 - Require Dart 3.0

gcp/lib/src/logging.dart

@@ -98,6 +98,8 @@ final _loggerKey = Object();
 
 /// Return [Middleware] that logs errors using Google Cloud structured logs and
 /// returns the correct response.
+/// Log messages of type [Map] are logged as structured logs (`jsonPayload`).
+/// All other logs messages are logged as text logs (`textPayload`).
 Middleware cloudLoggingMiddleware(String projectId) {
   Handler hostedLoggingMiddleware(Handler innerHandler) => (request) async {
         // Add log correlation to nest all log messages beneath request log in
@@ -229,13 +231,18 @@ class _CloudLogger extends RequestLogger {
   _CloudLogger(this._zone, this._traceId);
 
   @override
-  void log(Object message, LogSeverity severity) =>
-      _zone.print(_createLogEntry(_traceId, '$message', severity));
+  void log(Object message, LogSeverity severity) => _zone.print(
+        _createLogEntry(
+          _traceId,
+          message is Map ? message : '$message',
+          severity,
+        ),
+      );
 }
 
 String _createLogEntry(
   String? traceValue,
-  String message,
+  Object message,
   LogSeverity severity, {
   Frame? stackFrame,
 }) {

gcp/pubspec.yaml

@@ -1,7 +1,7 @@
 name: gcp
 description: >-
   Utilities for running Dart code correctly on the Google Cloud Platform.
-version: 0.1.1
+version: 0.1.2-wip
 repository: https://github.com/GoogleCloudPlatform/functions-framework-dart/tree/main/gcp
 
 environment: