Added new feature to track the past history of the Path value

readme.md

@@ -301,6 +301,43 @@ Would result in the following value of `s`:
 }
 ```
 
+Assume you update the phone number and country code entries for the same object. And then you want to access the old history, i.e., the past values before the update.
+
+```java
+d.setString("$.phones[0].number", "66666");
+d.setString("$.phones[0].country", "CA");
+String s = d.getPrettyPrintJson();
+```
+
+Would result in the following value of `s`:
+
+```json
+{
+  "first_name": "Deepak",
+  "phones": [
+    {
+      "type": "Home",
+      "number": "66666",
+      "country": "CA"
+    },
+    {
+      "type": "Cell",
+      "number": "333333",
+      "country": "USA"
+    }
+  ]
+}
+```
+
+And to access the previous values of phone and country code, you can use the following:
+
+```java
+Map<String, Object> pathPreviousValue = d.getPathHistory();
+String previousNumber = pathPreviousValue.get("$.phones[0].number").toString(); // will return 222222
+String previousCountry = pathPreviousValue.get("$.phones[0].country").toString(); // will return USA
+```
+
+
 Note that a new element has been created in the array. The same effect could also have been achieved by the following:
 
 ```java

src/main/java/com/americanexpress/unify/jdocs/CONSTS_JDOCS.java

@@ -44,6 +44,10 @@ private FORMAT_FIELDS() {
     public static final String MAX_VALUE = "max_value";
     public static final String MIN_DATE = "min_date";
     public static final String MAX_DATE = "max_date";
+    public static final String CREATED_PATH="created_path";
+    public static final String PATH_DOES_NOT_EXIST="path_does_not_exist";
+    public static final String MODIFIED_PATH="modified_path";
+
 
   }
 

src/main/java/com/americanexpress/unify/jdocs/Document.java

@@ -18,6 +18,7 @@
 
 import java.math.BigDecimal;
 import java.util.List;
+import java.util.Map;
 
 /*
  * @author Deepak Arora
@@ -31,6 +32,19 @@ public interface Document {
    */
   boolean isTyped();
 
+  /**
+   *
+   * @returns the modified values of the document
+   */
+  Map<String, Object> getPathHistory();
+
+  /**
+   * Returns the status of the modified value of the document
+   */
+
+
+  String getPathStatus(String path);
+
   /**
    * Returns the type of the document
    */

src/main/java/com/americanexpress/unify/jdocs/JDocument.java

@@ -43,6 +43,9 @@
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
+import static com.americanexpress.unify.jdocs.CONSTS_JDOCS.FORMAT_FIELDS.CREATED_PATH;
+import static com.americanexpress.unify.jdocs.CONSTS_JDOCS.FORMAT_FIELDS.MODIFIED_PATH;
+import static com.americanexpress.unify.jdocs.CONSTS_JDOCS.FORMAT_FIELDS.PATH_DOES_NOT_EXIST;
 import static com.americanexpress.unify.jdocs.DataType.DATE;
 import static com.americanexpress.unify.jdocs.DataType.STRING;
 
@@ -66,6 +69,9 @@ public class JDocument implements Document {
 
   private static CONSTS_JDOCS.VALIDATION_TYPE defaultValidationType = CONSTS_JDOCS.VALIDATION_TYPE.ALL_DATA_PATHS;
 
+  //to keep track of Modified values
+  private Map<String,Object> pathHistoricalVal =new HashMap<>();
+
   // type of the document
   private String docType = "";
 
@@ -248,6 +254,30 @@ private void init(String type, String json, CONSTS_JDOCS.VALIDATION_TYPE validat
     }
   }
 
+  /**
+   get a map of modified values
+   */
+  @Override
+  public Map<String, Object> getPathHistory(){
+    return pathHistoricalVal;
+  }
+
+
+  @Override
+  public String getPathStatus(String path){
+
+    if (!pathHistoricalVal.containsKey(path)) {
+      return PATH_DOES_NOT_EXIST;
+    }
+    if (pathHistoricalVal.get(path) == null) {
+      return CREATED_PATH;
+    }
+    // it is modified
+    return MODIFIED_PATH;
+
+
+  }
+
   /**
    * Gets the type of the document.
    *
@@ -1506,9 +1536,32 @@ protected final void setValue(String path, List<Token> tokenList, Object value,
           if (token.isArray()) {
             // set the value in the array
             ArrayToken at = (ArrayToken)token;
+            ArrayNode arrayNode= (ArrayNode) node;
+
+            int index=at.getFilter().getIndex();
+            if(index>=arrayNode.size()){
+              pathHistoricalVal.put(tokenPath+"["+index+"]", null);// new element added
+            }
+            else{
+              JsonNode oldValue = arrayNode.get(index);
+              if (!oldValue.equals(objectMapper.valueToTree(value))) {// only track if value changes
+                pathHistoricalVal.put(tokenPath + "[" + index + "]", oldValue.isTextual() ? oldValue.asText() : oldValue.deepCopy());
+              }
+            }
             setArrayIndexValue((ArrayNode)node, at.getFilter().getIndex(), value);
           }
           else {
+
+            //record the previous value for leaf node
+            ObjectNode objectNode = (ObjectNode)node;
+            JsonNode oldValue = objectNode.get(field);
+            // record addition or update
+            if (oldValue==null) {
+              pathHistoricalVal.put(tokenPath, null);// new element added
+            }
+            else if (oldValue != null && !oldValue.equals(objectMapper.valueToTree(value))) {
+              pathHistoricalVal.put(tokenPath , oldValue.isTextual() ? oldValue.asText() : oldValue.deepCopy());
+            }
             setLeafNode((ObjectNode)node, field, value);
           }
 

src/main/java/com/americanexpress/unify/jdocs/ReadOnlyDocument.java

@@ -19,6 +19,7 @@
 
 import java.math.BigDecimal;
 import java.util.List;
+import java.util.Map;
 
 /*
  * @author Deepak Arora
@@ -46,6 +47,16 @@ public boolean isTyped() {
     return d.isTyped();
   }
 
+  @Override
+  public Map<String, Object> getPathHistory() {
+    return d.getPathHistory();
+  }
+
+  @Override
+  public String getPathStatus(String path) {
+    return d.getPathStatus(path);
+  }
+
   @Override
   public String getType() {
     return d.getType();

src/test/java/com/americanexpress/unify/jdocs/DocumentTest.java

@@ -22,6 +22,7 @@
 import java.math.BigDecimal;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
 
 import static com.americanexpress.unify.jdocs.CONSTS_JDOCS.VALIDATION_TYPE.*;
 import static org.junit.jupiter.api.Assertions.*;
@@ -112,6 +113,32 @@ void testMisc() {
     b = d.isArray("$.house[0].family");
     assertEquals(false, b);
 
+    d=new JDocument();
+    String pathName="$.members[0].first_name";
+    String pathLastName="$.members[0].last_name";
+    d.setString(pathName, "Nilu");
+    d.setString(pathLastName, "Did");
+
+    // Verify the value is set correctly
+    assertTrue(d.pathExists("$.members[0].first_name", "Nilu"));
+    // modify the first name, and store the last value the pathHistoricalVal map
+    d.setString(pathName,"Joerge");
+    //check status of last name path , which is just created
+    assertEquals(d.getPathStatus(pathLastName),CONSTS_JDOCS.FORMAT_FIELDS.CREATED_PATH);
+    d.setString(pathLastName,"JJ");
+
+    //check status of last name path , which is modified now
+    assertEquals(d.getPathStatus(pathLastName),CONSTS_JDOCS.FORMAT_FIELDS.MODIFIED_PATH);
+    d.setString(pathName,"Sam");
+    d.setString(pathLastName,"S");
+
+    Map<String, Object> pathPreviousValue = d.getPathHistory();
+    // access the historical value (the previous value) of the first name and verify it
+    assertTrue(pathPreviousValue.containsKey(pathName)); // Ensure the path is tracked
+    assertEquals("Joerge", pathPreviousValue.get(pathName).toString());
+
+
+
     d = new JDocument("[]");
     d.setString("$.[0].name", "Deepak");
     d.setString("$.[1].name", "Nitika");