Bael 19 jackson inheritance (#954)

* BAEL-19 event inheritance

* BAEL-19 test for json inheritance

* BAEL-19 example event processor

* BAEL-19 do not need json ignore

* BAEL-19 simpler event, example of abstract

* BAEL-19 ignoring superclass property

* BAEL-586 change class event names

jackson/src/main/java/com/baeldung/jackson/inheritance/Event.java

@@ -0,0 +1,25 @@
+package com.baeldung.jackson.inheritance;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+
+@JsonTypeInfo(use = JsonTypeInfo.Id.MINIMAL_CLASS, include = JsonTypeInfo.As.PROPERTY, property = "eventType")
+abstract public class Event {
+    private final String id;
+    private final Long timestamp;
+
+    @JsonCreator
+    public Event(@JsonProperty("id") String id, @JsonProperty("timestamp") Long timestamp) {
+        this.id = id;
+        this.timestamp = timestamp;
+    }
+
+    public Long getTimestamp() {
+        return timestamp;
+    }
+
+    public String getId() {
+        return id;
+    }
+}

jackson/src/main/java/com/baeldung/jackson/inheritance/ItemIdAddedToUser.java

@@ -0,0 +1,31 @@
+package com.baeldung.jackson.inheritance;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonTypeName;
+
+@JsonTypeName("itemIdAddedToUser")
+@JsonIgnoreProperties("id")
+public class ItemIdAddedToUser extends Event {
+    private final String itemId;
+    private final Long quantity;
+
+    @JsonCreator
+    public ItemIdAddedToUser(@JsonProperty("id") String id,
+                             @JsonProperty("timestamp") Long timestamp,
+                             @JsonProperty("itemId") String itemId,
+                             @JsonProperty("quantity") Long quantity) {
+        super(id, timestamp);
+        this.itemId = itemId;
+        this.quantity = quantity;
+    }
+
+    public String getItemId() {
+        return itemId;
+    }
+
+    public Long getQuantity() {
+        return quantity;
+    }
+}

jackson/src/main/java/com/baeldung/jackson/inheritance/ItemIdRemovedFromUser.java

@@ -0,0 +1,29 @@
+package com.baeldung.jackson.inheritance;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.annotation.JsonTypeName;
+
+@JsonTypeName("itemIdRemovedFromUser")
+public class ItemIdRemovedFromUser extends Event {
+    private final String itemId;
+    private final Long quantity;
+
+    @JsonCreator
+    public ItemIdRemovedFromUser(@JsonProperty("id") String id,
+                                 @JsonProperty("timestamp") Long timestamp,
+                                 @JsonProperty("itemId") String itemId,
+                                 @JsonProperty("quantity") Long quantity) {
+        super(id, timestamp);
+        this.itemId = itemId;
+        this.quantity = quantity;
+    }
+
+    public String getItemId() {
+        return itemId;
+    }
+
+    public Long getQuantity() {
+        return quantity;
+    }
+}

jackson/src/test/java/com/baeldung/jackson/inheritance/ItemIdRemovedFromUserTest.java

@@ -0,0 +1,41 @@
+package com.baeldung.jackson.inheritance;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.Test;
+
+import java.io.IOException;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class ItemIdRemovedFromUserTest {
+    @Test
+    public void givenRemoveItemJson_whenDeserialize_shouldHaveProperClassType() throws IOException {
+        //given
+        Event event = new ItemIdRemovedFromUser("1", 12345567L, "item_1", 2L);
+        ObjectMapper objectMapper = new ObjectMapper();
+        String eventJson = objectMapper.writeValueAsString(event);
+
+        //when
+        Event result = new ObjectMapper().readValue(eventJson, Event.class);
+
+        //then
+        assertTrue(result instanceof ItemIdRemovedFromUser);
+        assertEquals("item_1", ((ItemIdRemovedFromUser) result).getItemId());
+    }
+
+    @Test
+    public void givenAdddItemJson_whenSerialize_shouldIgnoreIdPropertyFromSuperclass() throws IOException {
+        //given
+        Event event = new ItemIdAddedToUser("1", 12345567L, "item_1", 2L);
+        ObjectMapper objectMapper = new ObjectMapper();
+
+        //when
+        String eventJson = objectMapper.writeValueAsString(event);
+
+        //then
+        assertFalse(eventJson.contains("id"));
+    }
+
+}