provide the "ObjectMapper.treeToValue(TreeNode, TypeReference)" method (#4046) (#4056)

Author: fantasy0v0

src/main/java/com/fasterxml/jackson/databind/ObjectMapper.java

@@ -3485,6 +3485,20 @@ public <T> T treeToValue(TreeNode n, JavaType valueType)
         }
     }
 
+    /**
+     * Same as {@link #treeToValue(TreeNode, JavaType)} but target type specified
+     * using fully resolved {@link TypeReference}.
+     *
+     * @since 2.16
+     */
+    public <T> T treeToValue(TreeNode n, TypeReference<T> toValueTypeRef)
+        throws IllegalArgumentException,
+        JsonProcessingException
+    {
+        JavaType valueType = constructType(toValueTypeRef);
+        return treeToValue(n, valueType);
+    }
+
     /**
      * Method that is reverse of {@link #treeToValue}: it
      * will convert given Java value (usually bean) into its

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

@@ -8,6 +8,7 @@
 
 import static org.junit.Assert.*;
 
+import com.fasterxml.jackson.core.type.TypeReference;
 import org.junit.Assert;
 
 import com.fasterxml.jackson.annotation.JsonTypeInfo;
@@ -178,6 +179,17 @@ public void testTreeToValue() throws Exception
         // ... also JavaType
         r1 = mapper.treeToValue(root, mapper.constructType(Root.class));
         assertEquals(13, r1.leaf.value);
+
+        // ... also TypeReference
+        r1 = mapper.treeToValue(root, new TypeReference<Root>() {});
+        assertEquals(13, r1.leaf.value);
+
+        JSON = "[{\"leaf\":{\"value\":13}}, {\"leaf\":{\"value\":12}}]";
+        root = mapper.readTree(JSON);
+        List<Root> array = mapper.treeToValue(root, new TypeReference<List<Root>>() {});
+        assertEquals(2, array.size());
+        assertEquals(13, array.get(0).leaf.value);
+        assertEquals(12, array.get(1).leaf.value);
     }
 
     // [databind#1208]: should coerce POJOs at least at root level