From b5f517612583c5a8e1a2ba0762a06d3b136d7e7a Mon Sep 17 00:00:00 2001
From: Denis Stepanov <denis.s.stepanov@oracle.com>
Date: Mon, 5 Aug 2024 09:52:29 +0200
Subject: [PATCH] Don't use `DynamicMessageBodyWriter` (#765)

---
 .../micronaut/servlet/http/ServletHttpHandler.java  | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/servlet-core/src/main/java/io/micronaut/servlet/http/ServletHttpHandler.java b/servlet-core/src/main/java/io/micronaut/servlet/http/ServletHttpHandler.java
index 9f055eef8..469ed4475 100644
--- a/servlet-core/src/main/java/io/micronaut/servlet/http/ServletHttpHandler.java
+++ b/servlet-core/src/main/java/io/micronaut/servlet/http/ServletHttpHandler.java
@@ -26,6 +26,7 @@
 import io.micronaut.core.execution.ExecutionFlow;
 import io.micronaut.core.io.Writable;
 import io.micronaut.core.propagation.PropagatedContext;
+import io.micronaut.core.reflect.ClassUtils;
 import io.micronaut.core.type.Argument;
 import io.micronaut.core.util.ArrayUtils;
 import io.micronaut.http.HttpAttributes;
@@ -380,7 +381,7 @@ private void encodeResponse(ServletExchange<REQ, RES> exchange,
 
             if (body != null && !isVoid) {
                 Class<?> bodyType = body.getClass();
-                if (bodyArgument == null || !bodyArgument.isInstance(body)) {
+                if (bodyArgument == null || !bodyArgument.isInstance(body) || bodyArgument.getType().equals(Object.class)) {
                     bodyArgument = (Argument<Object>) Argument.of(bodyType);
                 }
                 ServletResponseEncoder<Object> responseEncoder = (ServletResponseEncoder<Object>) responseEncoders.get(bodyType);
@@ -421,7 +422,15 @@ private void encodeResponse(ServletExchange<REQ, RES> exchange,
                 if (!(body instanceof HttpStatus)) {
                     messageBodyWriter = routeInfoAttribute.map(RouteInfo::getMessageBodyWriter).orElse(null);
                     if (messageBodyWriter == null) {
-                        messageBodyWriter = new DynamicMessageBodyWriter(messageBodyHandlerRegistry, List.of(mediaType));
+                        MediaType finalMediaType = mediaType;
+                        Argument<Object> finalBodyArgument = bodyArgument;
+                        Optional<MessageBodyWriter<Object>> writer = messageBodyHandlerRegistry.findWriter(bodyArgument, List.of(mediaType));
+                        if (writer.isEmpty() && mediaType.equals(MediaType.TEXT_PLAIN_TYPE) && ClassUtils.isJavaBasicType(body.getClass())) {
+                            // TODO: remove after Core 4.6
+                            writer = (Optional) messageBodyHandlerRegistry.findWriter(Argument.STRING, List.of(MediaType.TEXT_PLAIN_TYPE));
+                        }
+                        messageBodyWriter = writer
+                            .orElseThrow(() -> new CodecException("Cannot encode value of argument [" + finalBodyArgument + "]. No possible encoders found for media type: " + finalMediaType));
                     }
                 }