BAEL-1187 - Mapping Nested Values with Jackson (#2750)

* BAEL-1187 - Mapping Nested Values with Jackson

* minor naming and formatting changes to align with standards

* update formatting and jackson version

jackson/pom.xml

@@ -129,7 +129,7 @@
 
     <properties>
         <!-- marshalling -->
-        <jackson.version>2.9.0</jackson.version>
+        <jackson.version>2.9.2</jackson.version>
 
         <!-- util -->
         <guava.version>19.0</guava.version>

jackson/src/test/java/com/baeldung/jackson/deserialization/nested/DeserializeWithNestedPropertiesUnitTest.java

@@ -0,0 +1,70 @@
+package com.baeldung.jackson.deserialization.nested;
+
+import static org.junit.Assert.*;
+
+import java.io.IOException;
+
+import org.junit.Test;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.module.SimpleModule;
+
+public class DeserializeWithNestedPropertiesUnitTest {
+
+    private String SOURCE_JSON = "{\"id\":\"957c43f2-fa2e-42f9-bf75-6e3d5bb6960a\",\"name\":\"The Best Product\",\"brand\":{\"id\":\"9bcd817d-0141-42e6-8f04-e5aaab0980b6\",\"name\":\"ACME Products\",\"owner\":{\"id\":\"b21a80b1-0c09-4be3-9ebd-ea3653511c13\",\"name\":\"Ultimate Corp, Inc.\"}}}";
+
+    @Test
+    public void whenUsingJacksonAnnotations_thenOk() throws IOException {
+        Product product = new ObjectMapper().readerFor(Product.class)
+            .readValue(SOURCE_JSON);
+
+        assertEquals(product.getName(), "The Best Product");
+        assertEquals(product.getBrandName(), "ACME Products");
+        assertEquals(product.getOwnerName(), "Ultimate Corp, Inc.");
+    }
+
+    @Test
+    public void whenUsingJacksonJsonNode_thenOk() throws IOException {
+        JsonNode productNode = new ObjectMapper().readTree(SOURCE_JSON);
+
+        Product product = new Product();
+        product.setId(productNode.get("id")
+            .textValue());
+        product.setName(productNode.get("name")
+            .textValue());
+        product.setBrandName(productNode.get("brand")
+            .get("name")
+            .textValue());
+        product.setOwnerName(productNode.get("brand")
+            .get("owner")
+            .get("name")
+            .textValue());
+
+        assertEquals(product.getName(), "The Best Product");
+        assertEquals(product.getBrandName(), "ACME Products");
+        assertEquals(product.getOwnerName(), "Ultimate Corp, Inc.");
+    }
+
+    @Test
+    public void whenUsingJacksonDeserializerManuallyRegistered_thenOk() throws IOException {
+        ObjectMapper mapper = new ObjectMapper();
+        SimpleModule module = new SimpleModule();
+        module.addDeserializer(Product.class, new ProductDeserializer());
+        mapper.registerModule(module);
+
+        Product product = mapper.readValue(SOURCE_JSON, Product.class);
+        assertEquals(product.getName(), "The Best Product");
+        assertEquals(product.getBrandName(), "ACME Products");
+        assertEquals(product.getOwnerName(), "Ultimate Corp, Inc.");
+    }
+
+    @Test
+    public void whenUsingJacksonDeserializerAutoRegistered_thenOk() throws IOException {
+        ObjectMapper mapper = new ObjectMapper();
+        Product product = mapper.readValue(SOURCE_JSON, Product.class);
+        assertEquals(product.getName(), "The Best Product");
+        assertEquals(product.getBrandName(), "ACME Products");
+        assertEquals(product.getOwnerName(), "Ultimate Corp, Inc.");
+    }
+}

jackson/src/test/java/com/baeldung/jackson/deserialization/nested/Product.java

@@ -0,0 +1,55 @@
+package com.baeldung.jackson.deserialization.nested;
+
+import java.util.Map;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+
+@JsonDeserialize(using = ProductDeserializer.class)
+public class Product {
+
+    private String id;
+    private String name;
+    private String brandName;
+    private String ownerName;
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getBrandName() {
+        return brandName;
+    }
+
+    public void setBrandName(String brandName) {
+        this.brandName = brandName;
+    }
+
+    public String getOwnerName() {
+        return ownerName;
+    }
+
+    public void setOwnerName(String ownerName) {
+        this.ownerName = ownerName;
+    }
+
+    @SuppressWarnings("unchecked")
+    @JsonProperty("brand")
+    private void unpackNested(Map<String, Object> brand) {
+        this.brandName = (String) brand.get("name");
+        Map<String, String> owner = (Map<String, String>) brand.get("owner");
+        this.ownerName = owner.get("name");
+    }
+}

jackson/src/test/java/com/baeldung/jackson/deserialization/nested/ProductDeserializer.java

@@ -0,0 +1,40 @@
+package com.baeldung.jackson.deserialization.nested;
+
+import java.io.IOException;
+
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.DeserializationContext;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
+
+@SuppressWarnings("serial")
+public class ProductDeserializer extends StdDeserializer<Product> {
+
+    public ProductDeserializer() {
+        this(null);
+    }
+
+    public ProductDeserializer(Class<?> vc) {
+        super(vc);
+    }
+
+    @Override
+    public Product deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
+        JsonNode productNode = jp.getCodec()
+            .readTree(jp);
+        Product product = new Product();
+        product.setId(productNode.get("id")
+            .textValue());
+        product.setName(productNode.get("name")
+            .textValue());
+        product.setBrandName(productNode.get("brand")
+            .get("name")
+            .textValue());
+        product.setOwnerName(productNode.get("brand")
+            .get("owner")
+            .get("name")
+            .textValue());
+        return product;
+    }
+}