Merge pull request #478 from BenFradet/issue/438

Do not map non-existing values, fixes #438

json-path/src/main/java/com/jayway/jsonpath/internal/PathRef.java

@@ -298,7 +298,9 @@ public abstract class PathRef implements Comparable<PathRef>  {
         public void convert(MapFunction mapFunction, Configuration configuration) {
             for (String property : properties) {
                 Object currentValue = configuration.jsonProvider().getMapValue(parent, property);
-                configuration.jsonProvider().setProperty(parent, property, mapFunction.map(currentValue, configuration));
+                if (currentValue != JsonProvider.UNDEFINED) {
+                    configuration.jsonProvider().setProperty(parent, property, mapFunction.map(currentValue, configuration));
+                }
             }
         }
 

json-path/src/test/java/com/jayway/jsonpath/JacksonJsonNodeJsonProviderTest.java

@@ -3,9 +3,13 @@ package com.jayway.jsonpath;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
 import com.fasterxml.jackson.databind.node.ArrayNode;
 import com.fasterxml.jackson.databind.node.JsonNodeFactory;
 import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.jayway.jsonpath.spi.json.JacksonJsonNodeJsonProvider;
+import com.jayway.jsonpath.spi.mapper.JacksonMappingProvider;
 import com.jayway.jsonpath.spi.mapper.MappingException;
 import org.junit.Test;
 
@@ -55,7 +59,7 @@ public class JacksonJsonNodeJsonProviderTest extends BaseTest {
         context.put("$", "child", child1);
         ObjectNode node2 = context.read("$");
         ObjectNode child2 = context.read("$.child");
-        
+
         assertThat(node1).isSameAs(node2);
         assertThat(child1).isSameAs(child2);
     }
@@ -112,7 +116,32 @@ public class JacksonJsonNodeJsonProviderTest extends BaseTest {
 
         using(JACKSON_JSON_NODE_CONFIGURATION).parse(JSON).read("$", typeRef);
     }
-    
+
+    @Test
+    public void mapPropertyWithPOJO() {
+        String someJson = "" +
+                "{\n" +
+                "  \"a\": \"a\",\n" +
+                "  \"b\": \"b\"\n" +
+                "}";
+        ObjectMapper om = new ObjectMapper();
+        om.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
+        Configuration c = Configuration
+                .builder()
+                .mappingProvider(new JacksonMappingProvider())
+                .jsonProvider(new JacksonJsonNodeJsonProvider(om))
+                .build();
+        DocumentContext context = JsonPath.using(c).parse(someJson);
+        String someJsonStr = context.jsonString();
+        DocumentContext altered = context.map("$['a', 'b', 'c']", new MapFunction() {
+            @Override
+            public Object map(Object currentValue, Configuration configuration) {
+                return currentValue;
+            }
+        });
+        assertThat(altered.jsonString()).isEqualTo(someJsonStr);
+    }
+
     @Test
     // https://github.com/json-path/JsonPath/issues/364
     public void setPropertyWithPOJO() {
@@ -161,7 +190,7 @@ public class JacksonJsonNodeJsonProviderTest extends BaseTest {
     public static class Gen {
         public String eric;
     }
-    
+
     public static final class Data {
       @JsonProperty("id")
       UUID id;