Fix #5237 (custom Map @JsonMerge fail) (#5251)

cowtowncoder · web-flow · commit ff8c5a22c630 · 2025-08-12T20:03:20.000-07:00
diff --git a/release-notes/VERSION-2.x b/release-notes/VERSION-2.x
@@ -6,6 +6,8 @@ Project: jackson-databind
 
 Not yet released
 
+#5237: Failing `@JsonMerge` with a custom Map with a `@JsonCreator` constructor
+ (reported by @nlisker)
 #5242: Support "binary vectors": `@JsonFormat(shape = Shape.BINARY)` for
   `float[]`, `double[]`
 
diff --git a/src/main/java/com/fasterxml/jackson/databind/deser/BeanDeserializer.java b/src/main/java/com/fasterxml/jackson/databind/deser/BeanDeserializer.java
@@ -476,6 +476,16 @@ protected Object _deserializeUsingPropertyBased(final JsonParser p, final Deseri
             if ((prop != null) &&
                 // [databind#3938]: except if it's MethodProperty
                 (!_beanType.isRecordType() || (prop instanceof MethodProperty))) {
+
+                // 12-Aug-2025, tatu: [databind#5237] Mergeable properties need
+                //    special handling: must defer deserialization until POJO
+                //    is constructed.
+                if (prop instanceof MergingSettableBeanProperty) {
+                    TokenBuffer tb = ctxt.bufferForInputBuffering(p);
+                    tb.copyCurrentStructure(p);
+                    buffer.bufferMergingProperty(prop, tb);
+                    continue;
+                }
                 try {
                     buffer.bufferProperty(prop, _deserializeWithErrorWrapping(p, ctxt, prop));
                 } catch (UnresolvedForwardReference reference) {
@@ -485,7 +495,7 @@ protected Object _deserializeUsingPropertyBased(final JsonParser p, final Deseri
                     BeanReferring referring = handleUnresolvedReference(ctxt,
                             prop, buffer, reference);
                     if (referrings == null) {
-                        referrings = new ArrayList<BeanReferring>();
+                        referrings = new ArrayList<>();
                     }
                     referrings.add(referring);
                 }
diff --git a/src/main/java/com/fasterxml/jackson/databind/deser/impl/PropertyBasedCreator.java b/src/main/java/com/fasterxml/jackson/databind/deser/impl/PropertyBasedCreator.java
@@ -273,7 +273,7 @@ public Object build(DeserializationContext ctxt, PropertyValueBuffer buffer) thr
 
             // Anything buffered?
             for (PropertyValue pv = buffer.buffered(); pv != null; pv = pv.next) {
-                pv.assign(bean);
+                pv.assign(ctxt, bean);
             }
         }
         return bean;
diff --git a/src/main/java/com/fasterxml/jackson/databind/deser/impl/PropertyValue.java b/src/main/java/com/fasterxml/jackson/databind/deser/impl/PropertyValue.java
@@ -2,8 +2,11 @@
 
 import java.io.IOException;
 
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.databind.DeserializationContext;
 import com.fasterxml.jackson.databind.deser.SettableAnyProperty;
 import com.fasterxml.jackson.databind.deser.SettableBeanProperty;
+import com.fasterxml.jackson.databind.util.TokenBuffer;
 
 /**
  * Base class for property values that need to be buffered during
@@ -24,12 +27,25 @@ protected PropertyValue(PropertyValue next, Object value)
         this.value = value;
     }
 
+    /**
+     * @deprecated Since 2.20 use {@link #assign(DeserializationContext, Object)}
+     */
+    @Deprecated // since 2.20
+    public final void assign(Object bean) throws IOException {
+        assign(null, bean);
+    }
+
     /**
      * Method called to assign stored value of this property to specified
      * bean instance
+     *
+     * @since 2.20
      */
-    public abstract void assign(Object bean)
-        throws IOException;
+    public void assign(DeserializationContext ctxt, Object bean)
+        throws IOException
+    {
+        throw new UnsupportedOperationException();
+    }
 
     /**
      * Method called to assign stored value of this property to specified
@@ -40,7 +56,7 @@ public abstract void assign(Object bean)
     public void setValue(Object parameterObject)
         throws IOException
     {
-        throw new UnsupportedOperationException("Should not be called by this type " + getClass().getName());
+        throw new UnsupportedOperationException("Should not be called on type: " + getClass().getName());
     }
 
     /*
@@ -66,7 +82,7 @@ public Regular(PropertyValue next, Object value,
         }
 
         @Override
-        public void assign(Object bean)
+        public void assign(DeserializationContext ctxt, Object bean)
             throws IOException
         {
             _property.set(bean, value);
@@ -95,7 +111,7 @@ public Any(PropertyValue next, Object value,
         }
 
         @Override
-        public void assign(Object bean)
+        public void assign(DeserializationContext ctxt, Object bean)
             throws IOException
         {
             _property.set(bean, _propertyName, value);
@@ -119,7 +135,7 @@ public Map(PropertyValue next, Object value, Object key)
 
         @SuppressWarnings("unchecked")
         @Override
-        public void assign(Object bean)
+        public void assign(DeserializationContext ctxt, Object bean)
             throws IOException
         {
             ((java.util.Map<Object,Object>) bean).put(_key, value);
@@ -148,7 +164,7 @@ public AnyParameter(PropertyValue next, Object value,
         }
 
         @Override
-        public void assign(Object bean)
+        public void assign(DeserializationContext ctxt, Object bean)
             throws IOException
         {
             // do nothing, as we are not assigning to a bean
@@ -163,4 +179,35 @@ public void setValue(Object parameterObject)
             _property.set(parameterObject, _propertyName, value);
         }
     }
+
+    /**
+     * Property value type used when merging values.
+     *
+     * @since 2.20
+     */
+    final static class Merging
+        extends PropertyValue
+    {
+        final SettableBeanProperty _property;
+
+        public Merging(PropertyValue next, TokenBuffer buffered,
+                       SettableBeanProperty prop)
+        {
+            super(next, buffered);
+            _property = prop;
+        }
+
+        @Override
+        public void assign(DeserializationContext ctxt, Object bean)
+            throws IOException
+        {
+            TokenBuffer buffered = (TokenBuffer) value;
+            try (JsonParser p = buffered.asParser()) {
+                p.nextToken();
+                // !!! 12-Aug-2025, tatu: We need DeserializationContext...
+                //   but for testing  just pass null for now.
+                _property.deserializeAndSet(p, ctxt, bean);
+            }
+        }
+    }
 }
diff --git a/src/main/java/com/fasterxml/jackson/databind/deser/impl/PropertyValueBuffer.java b/src/main/java/com/fasterxml/jackson/databind/deser/impl/PropertyValueBuffer.java
@@ -8,6 +8,7 @@
 import com.fasterxml.jackson.databind.deser.SettableAnyProperty;
 import com.fasterxml.jackson.databind.deser.SettableBeanProperty;
 import com.fasterxml.jackson.databind.introspect.AnnotatedMember;
+import com.fasterxml.jackson.databind.util.TokenBuffer;
 
 /**
  * Simple container used for temporarily buffering a set of
@@ -398,4 +399,9 @@ public void bufferMapProperty(Object key, Object value) {
     public void bufferAnyParameterProperty(SettableAnyProperty prop, String propName, Object value) {
         _anyParamBuffered = new PropertyValue.AnyParameter(_anyParamBuffered, value, prop, propName);
     }
+
+    // @since 2.20
+    public void bufferMergingProperty(SettableBeanProperty prop, TokenBuffer buffered) {
+        _buffered = new PropertyValue.Merging(_buffered, buffered, prop);
+    }
 }
diff --git a/src/test/java/com/fasterxml/jackson/databind/deser/merge/CustomMapMerge5237Test.java b/src/test/java/com/fasterxml/jackson/databind/deser/merge/CustomMapMerge5237Test.java
@@ -0,0 +1,63 @@
+package com.fasterxml.jackson.databind.deser.merge;
+
+import java.util.*;
+
+import org.junit.jupiter.api.Test;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonMerge;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.testutil.DatabindTestUtil;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+@SuppressWarnings("serial")
+public class CustomMapMerge5237Test
+    extends DatabindTestUtil
+{
+    // [databind#5237]
+    interface MyMap<K, V> extends Map<K, V> {}
+
+    static class MapImpl<K, V> extends HashMap<K, V> implements MyMap<K, V> {}
+
+    static class MergeMap {
+        int inter;
+        String s;
+
+        @JsonMerge
+        public MyMap<Integer, String> map = new MapImpl<>();
+
+        @JsonCreator
+        MergeMap(@JsonProperty("inter") int inter, @JsonProperty("s") String s) {
+             this.inter = inter;
+             this.s = s;
+        }
+
+        public int getInter() {
+             return inter;
+        }
+    }
+
+    private final ObjectMapper MAPPER = newJsonMapper();
+    
+    // [databind#5237]: Merge for custom maps fails
+    @Test
+    void customMapMerging5237() throws Exception
+    {
+        String json = "{\n"
+                + "  \"inter\" : 5,\n"
+                + "  \"map\" : {\n"
+                + "    \"3\" : \"ADS\"\n"
+                + "  },\n"
+                + "  \"s\" : \"abc\"\n"
+                + "}";
+        MergeMap merge2 = MAPPER.readValue(json, MergeMap.class);
+        assertNotNull(merge2);
+        assertEquals(Collections.singletonMap(3, "ADS"), merge2.map);
+        assertEquals(5, merge2.getInter());
+        assertEquals("abc", merge2.s);
+    }
+}

Original file line number	Diff line number	Diff line change
`@@ -273,7 +273,7 @@ public Object build(DeserializationContext ctxt, PropertyValueBuffer buffer) thr`
`273`	`273`
`274`	`274`	`// Anything buffered?`
`275`	`275`	`for (PropertyValue pv = buffer.buffered(); pv != null; pv = pv.next) {`
`276`		`- pv.assign(bean);`
	`276`	`+ pv.assign(ctxt, bean);`
`277`	`277`	`}`
`278`	`278`	`}`
`279`	`279`	`return bean;`