[BAEL-9628] Resolving Exception: cannot deserialize from Object value (no delegate- or property-based Creator)

jackson-modules/jackson-exceptions/pom.xml

@@ -12,6 +12,14 @@
         <version>0.0.1-SNAPSHOT</version>
     </parent>
 
+    <dependencies>
+        <dependency>
+            <groupId>com.fasterxml.jackson.module</groupId>
+            <artifactId>jackson-module-paranamer</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+    </dependencies>
+
     <build>
         <finalName>jackson-exceptions</finalName>
         <resources>

jackson-modules/jackson-exceptions/src/main/java/com/baeldung/invaliddefinitionexception/Notification.java

@@ -0,0 +1,20 @@
+package com.baeldung.invaliddefinitionexception;
+
+public class Notification {
+
+    private final String message;
+    private final int priority;
+
+    public Notification(String message, int priority) {
+        this.message = message;
+        this.priority = priority;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public int getPriority() {
+        return priority;
+    }
+}

jackson-modules/jackson-exceptions/src/main/java/com/baeldung/invaliddefinitionexception/NotificationWithCreator.java

@@ -0,0 +1,24 @@
+package com.baeldung.invaliddefinitionexception;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+public class NotificationWithCreator {
+
+    private final String message;
+    private final int priority;
+
+    @JsonCreator
+    public NotificationWithCreator(@JsonProperty("message") String message, @JsonProperty("priority") int priority) {
+        this.message = message;
+        this.priority = priority;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public int getPriority() {
+        return priority;
+    }
+}

jackson-modules/jackson-exceptions/src/main/java/com/baeldung/invaliddefinitionexception/NotificationWithDefaultConstructor.java

@@ -0,0 +1,26 @@
+package com.baeldung.invaliddefinitionexception;
+
+public class NotificationWithDefaultConstructor {
+
+    private String message;
+    private int priority;
+
+    public NotificationWithDefaultConstructor() {
+    }
+
+    public String getMessage() {
+        return message;
+    }
+
+    public void setMessage(String message) {
+        this.message = message;
+    }
+
+    public int getPriority() {
+        return priority;
+    }
+
+    public void setPriority(int priority) {
+        this.priority = priority;
+    }
+}

jackson-modules/jackson-exceptions/src/test/java/com/baeldung/invaliddefinitionexception/NotificationDeserializationUnitTest.java

@@ -0,0 +1,56 @@
+package com.baeldung.invaliddefinitionexception;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.exc.InvalidDefinitionException;
+import com.fasterxml.jackson.module.paranamer.ParanamerModule;
+
+class NotificationDeserializationUnitTest {
+
+    private static final String JSON = "{\"message\":\"Server maintenance\",\"priority\":2}";
+
+    private final ObjectMapper objectMapper = new ObjectMapper();
+
+    @Test
+    void givenNotificationWithoutCreator_whenDeserializing_thenThrowException() {
+        InvalidDefinitionException exception = assertThrows(InvalidDefinitionException.class, () -> objectMapper.readValue(JSON, Notification.class));
+
+        assertTrue(exception.getMessage()
+            .contains("no Creators, like default constructor, exist"));
+    }
+
+    @Test
+    void givenNotificationWithDefaultConstructor_whenDeserializing_thenCorrect() throws Exception {
+
+        NotificationWithDefaultConstructor notification = objectMapper.readValue(JSON, NotificationWithDefaultConstructor.class);
+
+        assertEquals("Server maintenance", notification.getMessage());
+        assertEquals(2, notification.getPriority());
+    }
+
+    @Test
+    void givenNotificationWithCreator_whenDeserializing_thenCorrect() throws Exception {
+
+        NotificationWithCreator notification = objectMapper.readValue(JSON, NotificationWithCreator.class);
+
+        assertEquals("Server maintenance", notification.getMessage());
+        assertEquals(2, notification.getPriority());
+    }
+
+    @Test
+    void givenParanamerModule_whenDeserializingNotification_thenCorrect() throws Exception {
+
+        ObjectMapper mapper = new ObjectMapper();
+        mapper.registerModule(new ParanamerModule());
+
+        Notification notification = mapper.readValue(JSON, Notification.class);
+
+        assertEquals("Server maintenance", notification.getMessage());
+        assertEquals(2, notification.getPriority());
+    }
+}