Fix #4355: don't fail getting serializer for Enum with toString()…

… returning null

release-notes/VERSION-2.x

@@ -17,6 +17,9 @@ Project: jackson-databind
 #4316: NPE when deserializing `JsonAnySetter` in `Throwable`
  (reported by @jpraet)
  (fix contributed by Joo-Hyuk K)
+#4355: Jackson 2.16 fails attempting to obtain `ObjectWriter` for an `Enum` of which
+ some value returns null from `toString()`
+ (reported by @YutaHiguchi-bsn)
 
 2.16.1 (24-Dec-2023)
 

src/main/java/com/fasterxml/jackson/databind/util/EnumValues.java

@@ -129,6 +129,11 @@ public static EnumValues constructFromToString(MapperConfig<?> config, Annotated
  if (name == null) {
  Enum<?> en = enumConstants[i];
  name = en.toString();
+ // 01-Feb-2024, tatu: [databind#4355] Nulls not great but... let's
+ // coerce into "" for backwards compatibility
+ if (name == null) {
+ name = "";
+ }
  }
  if (useLowerCase) {
  name = name.toLowerCase();

src/test/java/com/fasterxml/jackson/databind/deser/enums/EnumWithNullToString4355Test.java

@@ -0,0 +1,32 @@
+package com.fasterxml.jackson.databind.deser.enums;
+
+import com.fasterxml.jackson.databind.*;
+
+public class EnumWithNullToString4355Test extends BaseMapTest
+{
+ // [databind#4355]
+ enum Enum4355 {
+ ALPHA("A"),
+ BETA("B"),
+ UNDEFINED(null);
+
+ private final String s;
+
+ Enum4355(String s) {
+ this.s = s;
+ }
+
+ @Override
+ public String toString() {
+ return s;
+ }
+ }
+
+ private final ObjectMapper MAPPER = newJsonMapper();
+
+ // [databind#4355]
+ public void testWithNullToString() throws Exception
+ {
+ assertEquals("\"ALPHA\"", MAPPER.writeValueAsString(Enum4355.ALPHA)); 
+ }
+}