Added renameKey feature to rename a key value found in a map path to a new key value.

json-path/src/main/java/com/jayway/jsonpath/JsonPath.java

@@ -276,6 +276,17 @@ public class JsonPath {
         return resultByConfiguration(jsonObject, configuration, evaluationContext);
     }
 
+    public <T> T renameKey(Object jsonObject, String oldKeyName, String newKeyName, Configuration configuration){
+        notNull(jsonObject, "json can not be null");
+        notEmpty(newKeyName, "newKeyName can not be null or empty");
+        notNull(configuration, "configuration can not be null");
+        EvaluationContext evaluationContext = path.evaluate(jsonObject, jsonObject, configuration, true);
+        for (PathRef updateOperation : evaluationContext.updateOperations()) {
+            updateOperation.renameKey(oldKeyName, newKeyName, configuration);
+        }
+        return resultByConfiguration(jsonObject, configuration, evaluationContext);
+    }
+
     /**
      * Applies this JsonPath to the provided json string
      *

json-path/src/main/java/com/jayway/jsonpath/WriteContext.java

@@ -116,6 +116,7 @@ public interface WriteContext {
      */
     DocumentContext put(String path, String key, Object value, Predicate... filters);
 
+
     /**
      * Add or update the key with a the given value at the given path
      *
@@ -126,4 +127,28 @@ public interface WriteContext {
      */
     DocumentContext put(JsonPath path, String key, Object value);
 
-}
+    /**
+     * Renames the last key element of a given path.
+     * @param path          The path to the old key. Should be resolved to a map
+     *                      or an array including map items.
+     * @param oldKeyName    The old key name.
+     * @param newKeyName    The new key name.
+     * @param filters       filters.
+     * @return a document content.
+     */
+    DocumentContext renameKey(String path, String oldKeyName, String newKeyName, Predicate... filters);
+
+    /**
+     * Renames the last key element of a given path.
+     * @param path          The path to the old key. Should be resolved to a map
+     *                      or an array including map items.
+     * @param oldKeyName    The old key name.
+     * @param newKeyName    The new key name.
+     * @return a document content.
+     */
+    DocumentContext renameKey(JsonPath path, String oldKeyName, String newKeyName);
+
+//    DocumentContext replace(String path, String newKey, Predicate... filters);
+//    DocumentContext replace(JsonPath path, String newKey);
+
+}

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

@@ -231,6 +231,23 @@ public class JsonReader implements ParseContext, DocumentContext {
         return put(compile(path, filters), key, value);
     }
 
+    @Override
+    public DocumentContext renameKey(String path, String oldKeyName, String newKeyName, Predicate... filters) {
+        return renameKey(compile(path, filters), oldKeyName, newKeyName);
+    }
+
+    @Override
+    public DocumentContext renameKey(JsonPath path, String oldKeyName, String newKeyName) {
+        List<String> modified =  path.renameKey(json, oldKeyName, newKeyName, configuration.addOptions(Option.AS_PATH_LIST));
+        if(logger.isDebugEnabled()){
+            for (String p : modified) {
+                logger.debug("Rename path {} new value {}", p, newKeyName);
+            }
+        }
+        return this;
+    }
+
+
     @Override
     public DocumentContext put(JsonPath path, String key, Object value){
         List<String> modified = path.put(json, key, value, configuration.addOptions(Option.AS_PATH_LIST));

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

@@ -2,6 +2,7 @@ package com.jayway.jsonpath.internal;
 
 import com.jayway.jsonpath.Configuration;
 import com.jayway.jsonpath.InvalidModificationException;
+import com.jayway.jsonpath.JsonPath;
 import com.jayway.jsonpath.spi.json.JsonProvider;
 
 import java.util.Collection;
@@ -25,6 +26,10 @@ public abstract class PathRef implements Comparable<PathRef>  {
 
         @Override
         public void put(String key, Object newVal, Configuration configuration) {}
+
+        @Override
+        public void renameKey(String oldKeyName, String newKeyName, Configuration configuration) {}
+
     };
 
     protected Object parent;
@@ -44,6 +49,21 @@ public abstract class PathRef implements Comparable<PathRef>  {
 
     public abstract void put(String key, Object newVal, Configuration configuration);
 
+    public abstract void renameKey(String oldKey,String newKeyName, Configuration configuration);
+
+    protected void renameInMap(Object targetMap, String oldKeyName, String newKeyName, Configuration configuration){
+        if(configuration.jsonProvider().isMap(targetMap)){
+            configuration.jsonProvider().setProperty(targetMap, newKeyName, configuration.jsonProvider().getMapValue(targetMap, oldKeyName));
+            configuration.jsonProvider().removeProperty(targetMap, oldKeyName);
+        } else {
+            throw new InvalidModificationException("Can only rename properties in a map");
+        }
+    }
+
+    protected boolean targetInvalid(Object target){
+        return target == JsonProvider.UNDEFINED || target == null;
+    }
+
     @Override
     public int compareTo(PathRef o) {
         return this.getAccessor().toString().compareTo(o.getAccessor().toString()) * -1;
@@ -103,6 +123,16 @@ public abstract class PathRef implements Comparable<PathRef>  {
                 throw new InvalidModificationException("Invalid put operation. $ is not a map");
             }
         }
+
+        @Override
+        public void renameKey(String oldKeyName, String newKeyName, Configuration configuration) {
+            Object target = parent;
+            if(targetInvalid(target)){
+                return;
+            }
+            renameInMap(target, oldKeyName, newKeyName, configuration);
+        }
+
     }
     private static class ArrayIndexPathRef extends PathRef {
 
@@ -123,7 +153,7 @@ public abstract class PathRef implements Comparable<PathRef>  {
 
         public void add(Object value, Configuration configuration){
             Object target = configuration.jsonProvider().getArrayIndex(parent, index);
-            if(target == JsonProvider.UNDEFINED || target == null){
+            if(targetInvalid(target)){
                 return;
             }
             if(configuration.jsonProvider().isArray(target)){
@@ -135,7 +165,7 @@ public abstract class PathRef implements Comparable<PathRef>  {
 
         public void put(String key, Object value, Configuration configuration){
             Object target = configuration.jsonProvider().getArrayIndex(parent, index);
-            if(target == JsonProvider.UNDEFINED || target == null){
+            if(targetInvalid(target)){
                 return;
             }
             if(configuration.jsonProvider().isMap(target)){
@@ -145,6 +175,15 @@ public abstract class PathRef implements Comparable<PathRef>  {
             }
         }
 
+        @Override
+        public void renameKey(String oldKeyName, String newKeyName, Configuration configuration) {
+            Object target = configuration.jsonProvider().getArrayIndex(parent, index);
+            if(targetInvalid(target)){
+                return;
+            }
+            renameInMap(target, oldKeyName, newKeyName, configuration);
+        }
+
         @Override
         public Object getAccessor() {
             return index;
@@ -172,7 +211,7 @@ public abstract class PathRef implements Comparable<PathRef>  {
 
         public void add(Object value, Configuration configuration){
             Object target = configuration.jsonProvider().getMapValue(parent, property);
-            if(target == JsonProvider.UNDEFINED || target == null){
+            if(targetInvalid(target)){
                 return;
             }
             if(configuration.jsonProvider().isArray(target)){
@@ -184,7 +223,7 @@ public abstract class PathRef implements Comparable<PathRef>  {
 
         public void put(String key, Object value, Configuration configuration){
             Object target = configuration.jsonProvider().getMapValue(parent, property);
-            if(target == JsonProvider.UNDEFINED || target == null){
+            if(targetInvalid(target)){
                 return;
             }
             if(configuration.jsonProvider().isMap(target)){
@@ -194,6 +233,15 @@ public abstract class PathRef implements Comparable<PathRef>  {
             }
         }
 
+        @Override
+        public void renameKey(String oldKeyName, String newKeyName, Configuration configuration) {
+            Object target = configuration.jsonProvider().getMapValue(parent, property);
+            if(targetInvalid(target)){
+                return;
+            }
+            renameInMap(target, oldKeyName, newKeyName, configuration);
+        }
+
         @Override
         public Object getAccessor() {
             return property;
@@ -228,7 +276,12 @@ public abstract class PathRef implements Comparable<PathRef>  {
 
         @Override
         public void put(String key, Object newVal, Configuration configuration) {
-            throw new InvalidModificationException("Add can not be performed to multiple properties");
+            throw new InvalidModificationException("Put can not be performed to multiple properties");
+        }
+
+        @Override
+        public void renameKey(String oldKeyName, String newKeyName, Configuration configuration) {
+            throw new InvalidModificationException("Rename can not be performed to multiple properties");
         }
 
         @Override

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

@@ -2,10 +2,7 @@ package com.jayway.jsonpath;
 
 import org.junit.Test;
 
-import java.util.HashMap;
-import java.util.LinkedList;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 
 import static com.jayway.jsonpath.JsonPath.parse;
 import static java.util.Collections.emptyMap;
@@ -214,6 +211,38 @@ public class WriteTest extends BaseTest {
         parse(model).set("$[?(@.a == 'a-val')]", 1);
     }
 
+    @Test
+    public void a_path_can_be_renamed(){
+        Object o = parse(JSON_DOCUMENT).renameKey("$.store", "book", "updated-book").json();
+        List<Object> result = parse(o).read("$.store.updated-book");
+
+        assertThat(result).isNotEmpty();
+    }
+
+    @Test
+    public void keys_in_root_containing_map_can_be_renamed(){
+        Object o = parse(JSON_DOCUMENT).renameKey("$", "store", "new-store").json();
+        List<Object> result = parse(o).read("$.new-store[*]");
+        assertThat(result).isNotEmpty();
+    }
+
+    @Test
+    public void map_array_items_can_be_renamed(){
+        Object o = parse(JSON_DOCUMENT).renameKey("$.store.book[*]", "category", "renamed-category").json();
+        List<Object> result = parse(o).read("$.store.book[*].renamed-category");
+        assertThat(result).isNotEmpty();
+    }
 
+    @Test(expected = InvalidModificationException.class)
+    public void non_map_array_items_cannot_be_renamed(){
+        List<Integer> model = new LinkedList<Integer>();
+        model.add(1);
+        model.add(2);
+        parse(model).renameKey("$[*]", "oldKey", "newKey");
+    }
 
-}
+    @Test(expected = InvalidModificationException.class)
+    public void multiple_properties_cannot_be_renamed(){
+        parse(JSON_DOCUMENT).renameKey("$.store.book[*]['author', 'category']", "old-key", "new-key");
+    }
+}