Add new JsonNodeFeature.USE_BIG_DECIMAL_FOR_FLOATS (#5058)

Author: JooHyukKim

src/main/java/com/fasterxml/jackson/databind/cfg/JsonNodeFeature.java

@@ -79,7 +79,30 @@ public enum JsonNodeFeature implements DatatypeFeature
      *
      * @since 2.16
      */
-    FAIL_ON_NAN_TO_BIG_DECIMAL_COERCION(false)
+    FAIL_ON_NAN_TO_BIG_DECIMAL_COERCION(false),
+
+    /**
+     * Determines whether floating-point numbers should be deserialized into
+     * {@link java.math.BigDecimal} when reading {@link com.fasterxml.jackson.databind.JsonNode}s.
+     * This feature provides more precise control over number deserialization for {@code JsonNode}
+     * and takes precedence over {@link com.fasterxml.jackson.databind.DeserializationFeature#USE_BIG_DECIMAL_FOR_FLOATS}
+     * if explicitly set.
+     *
+     * <p>
+     * Behavior follows these rules:
+     * <ul>
+     *   <li>If explicitly enabled, floating-point numbers will be read as {@link java.math.BigDecimal}.</li>
+     *   <li>If explicitly disabled, floating-point numbers will be read as {@link java.lang.Double}.</li>
+     *   <li>If left undefined (default), the behavior follows {@code DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS}.</li>
+     * </ul>
+     *
+     * <p>
+     * Default value is {@code false} but unless explicitly set, handling
+     * depends on more general {@code DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS}).
+     *
+     * @since 2.19
+     */
+    USE_BIG_DECIMAL_FOR_FLOATS(false),
     ;
 
     private final static int FEATURE_INDEX = DatatypeFeatures.FEATURE_INDEX_JSON_NODE;

src/main/java/com/fasterxml/jackson/databind/deser/std/JsonNodeDeserializer.java

@@ -765,7 +765,15 @@ protected final JsonNode _fromFloat(JsonParser p, DeserializationContext ctxt,
         if (nt == JsonParser.NumberTypeFP.BIG_DECIMAL) {
             return _fromBigDecimal(ctxt, nodeFactory, p.getDecimalValue());
         }
-        if (ctxt.isEnabled(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS)) {
+
+        // [databind#4801] Add JsonNodeFeature.USE_BIG_DECIMAL_FOR_FLOATS
+        DatatypeFeatures dtf = ctxt.getDatatypeFeatures();
+        Boolean dtfState = dtf.getExplicitState(JsonNodeFeature.USE_BIG_DECIMAL_FOR_FLOATS);
+        boolean useBigDecimal = (dtfState == null) // not explicitly set
+                ? ctxt.isEnabled(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS)
+                    : dtfState.booleanValue();
+
+        if (useBigDecimal) {
             // [databind#4194] Add an option to fail coercing NaN to BigDecimal
             // Currently, Jackson 2.x allows such coercion, but Jackson 3.x will not
             if (p.isNaN()) {

src/test/java/com/fasterxml/jackson/databind/node/NodeFeaturesTest.java

@@ -1,5 +1,7 @@
 package com.fasterxml.jackson.databind.node;
 
+import java.math.BigDecimal;
+
 import org.junit.jupiter.api.Test;
 
 import com.fasterxml.jackson.databind.*;
@@ -156,4 +158,56 @@ public void testWriteSortedProperties() throws Exception
     /* Other features
     /**********************************************************************
      */
+
+    // [databind#4801] USE_BIG_DECIMAL_FOR_FLOATS
+    @Test
+    public void testBigDecimalForJsonNodeFeature() throws Exception {
+        final String JSON = "0.1234567890123456789012345678912345"; // Precision-sensitive
+
+        BigDecimal expectedBigDecimal = new BigDecimal("0.1234567890123456789012345678912345"); // Full precision
+        BigDecimal expectedDoubleLossy = new BigDecimal("0.12345678901234568"); // Precision loss
+
+        ObjectMapper mapper;
+
+        // Case 1: Both enabled → Should use BigDecimal
+        mapper = JsonMapper.builder()
+                .enable(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS)
+                .enable(JsonNodeFeature.USE_BIG_DECIMAL_FOR_FLOATS)
+                .build();
+        assertEquals(expectedBigDecimal, mapper.readTree(JSON).decimalValue());
+
+        // Case 2: Global enabled, JsonNodeFeature disabled → Should use Double (truncated decimal)
+        mapper = JsonMapper.builder()
+                .enable(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS)
+                .disable(JsonNodeFeature.USE_BIG_DECIMAL_FOR_FLOATS)
+                .build();
+        assertEquals(expectedDoubleLossy, mapper.readTree(JSON).decimalValue());
+
+        // Case 3: Global enabled, JsonNodeFeature undefined → Should use BigDecimal (default to global)
+        mapper = JsonMapper.builder()
+                .enable(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS)
+                .build();
+        assertEquals(expectedBigDecimal, mapper.readTree(JSON).decimalValue());
+
+        // Case 4: Global disabled, JsonNodeFeature enabled → Should use BigDecimal
+        mapper = JsonMapper.builder()
+                .disable(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS)
+                .enable(JsonNodeFeature.USE_BIG_DECIMAL_FOR_FLOATS)
+                .build();
+        assertEquals(expectedBigDecimal, mapper.readTree(JSON).decimalValue());
+
+        // Case 5: Both disabled → Should use Double (truncated decimal)
+        mapper = JsonMapper.builder()
+                .disable(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS)
+                .disable(JsonNodeFeature.USE_BIG_DECIMAL_FOR_FLOATS)
+                .build();
+        assertEquals(expectedDoubleLossy, mapper.readTree(JSON).decimalValue());
+
+        // Case 6: Global disabled, JsonNodeFeature undefined → Should use Double (default to global, truncated decimal)
+        mapper = JsonMapper.builder()
+                .disable(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS)
+                .build();
+        assertEquals(expectedDoubleLossy, mapper.readTree(JSON).decimalValue());
+    }
+
 }