BAEL-2890 (#6905)

jackson-2/README.md

@@ -7,3 +7,4 @@ The "REST With Spring" Classes: http://bit.ly/restwithspring
 
 ### Relevant Articles: 
 - [Mapping Multiple JSON Fields to a Single Java Field](https://www.baeldung.com/json-multiple-fields-single-java-field)
+- [Working with Tree Model Nodes in Jackson](https://www.baeldung.com/jackson-json-node-tree-model)

jackson-2/src/main/java/com/baeldung/jackson/node/JsonNodeIterator.java

@@ -0,0 +1,62 @@
+package com.baeldung.jackson.node;
+
+import java.util.Iterator;
+import java.util.Map.Entry;
+
+import com.fasterxml.jackson.databind.JsonNode;
+
+public class JsonNodeIterator {
+    
+    private static final String NEW_LINE = "\n";
+    private static final String FIELD_DELIMITER = ": ";
+    private static final String ARRAY_PREFIX = "- ";
+    private static final String YAML_PREFIX = "  ";
+    
+    public String toYaml(JsonNode root) {
+        StringBuilder yaml = new StringBuilder();
+        processNode(root, yaml, 0);
+        return yaml.toString();
+    }
+
+    private void processNode(JsonNode jsonNode, StringBuilder yaml, int depth) {
+        if (jsonNode.isValueNode()) {
+            yaml.append(jsonNode.asText());
+        }
+        else if (jsonNode.isArray()) {
+            for (JsonNode arrayItem : jsonNode) {
+                appendNodeToYaml(arrayItem, yaml, depth, true);
+            }
+        }
+        else if (jsonNode.isObject()) {
+            appendNodeToYaml(jsonNode, yaml, depth, false);
+        }
+    }
+    
+    private void appendNodeToYaml(JsonNode node, StringBuilder yaml, int depth, boolean isArrayItem) {
+        Iterator<Entry<String, JsonNode>> fields = node.fields();
+        boolean isFirst = true;
+        while (fields.hasNext()) {
+            Entry<String, JsonNode> jsonField = fields.next();
+            addFieldNameToYaml(yaml, jsonField.getKey(), depth, isArrayItem && isFirst);
+            processNode(jsonField.getValue(), yaml, depth+1);
+            isFirst = false;
+        }
+        
+    }
+
+private void addFieldNameToYaml(StringBuilder yaml, String fieldName, int depth, boolean isFirstInArray) {
+    if (yaml.length()>0) {
+        yaml.append(NEW_LINE);
+        int requiredDepth = (isFirstInArray) ? depth-1 : depth;
+        for(int i = 0; i < requiredDepth; i++) {
+            yaml.append(YAML_PREFIX);
+        }
+        if (isFirstInArray) {
+            yaml.append(ARRAY_PREFIX);
+        }
+    }
+    yaml.append(fieldName);
+    yaml.append(FIELD_DELIMITER);
+}
+
+}

jackson-2/src/test/java/com/baeldung/jackson/node/JsonNodeIteratorUnitTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.jackson.node;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+
+import org.junit.Test;
+
+import com.fasterxml.jackson.databind.JsonNode;
+
+public class JsonNodeIteratorUnitTest {
+
+    private JsonNodeIterator onTest = new JsonNodeIterator();
+    private static String expectedYaml = "name: \n" + 
+        "  first: Tatu\n" + 
+        "  last: Saloranta\n" + 
+        "title: Jackson founder\n" + 
+        "company: FasterXML\n" + 
+        "pets: \n" + 
+        "- type: dog\n" + 
+        "  number: 1\n" + 
+        "- type: fish\n" + 
+        "  number: 50";
+    
+@Test
+public void givenANodeTree_whenIteratingSubNodes_thenWeFindExpected() throws IOException {
+    final JsonNode rootNode = ExampleStructure.getExampleRoot();
+    
+    String yaml = onTest.toYaml(rootNode);
+    System.out.println(yaml.toString());
+
+    assertEquals(expectedYaml, yaml);
+    
+}
+
+
+}

jackson-2/src/test/resources/node_example.json

@@ -0,0 +1,18 @@
+{
+    "name": {
+        "first": "Tatu",
+        "last": "Saloranta"
+    },
+    "title": "Jackson founder",
+    "company": "FasterXML",
+    "pets": [
+        {
+            "type": "dog",
+            "number": 1
+        },
+        {
+            "type": "fish",
+            "number": 50
+        }
+    ]
+}

jackson/README.md

@@ -15,7 +15,6 @@ The "REST With Spring" Classes: http://bit.ly/restwithspring
 - [Jackson JSON Tutorial](http://www.baeldung.com/jackson)
 - [Jackson – Working with Maps and nulls](http://www.baeldung.com/jackson-map-null-values-or-null-key)
 - [Jackson – Decide What Fields Get Serialized/Deserialized](http://www.baeldung.com/jackson-field-serializable-deserializable-or-not)
-- [Working with Tree Model Nodes in Jackson](http://www.baeldung.com/jackson-json-node-tree-model)
 - [Jackson vs Gson](http://www.baeldung.com/jackson-vs-gson)
 - [XML Serialization and Deserialization with Jackson](http://www.baeldung.com/jackson-xml-serialization-and-deserialization)
 - [More Jackson Annotations](http://www.baeldung.com/jackson-advanced-annotations)

jackson/src/main/resources/node_example.json

@@ -1,10 +0,0 @@
-{
-	"name": 
-	{
-		"first": "Tatu",
-		"last": "Saloranta"
-	},
-
-	"title": "Jackson founder",
-	"company": "FasterXML"
-}