From b0a84c94d219b5a091727a76aadb65e895a32e4b Mon Sep 17 00:00:00 2001
From: Forb Yuan <f0rb@163.com>
Date: Mon, 3 Apr 2023 20:47:51 -0700
Subject: [PATCH] [BAEL-6203] Deserialize Generic Type with Jackson (#13764)

---
 .../jsongeneric/JsonResponse.java             | 14 +++++++
 .../deserialization/jsongeneric/User.java     | 33 +++++++++++++++
 .../GenericTypeDeserializerUnitTest.java      | 40 +++++++++++++++++++
 3 files changed, 87 insertions(+)
 create mode 100644 jackson-modules/jackson-core/src/main/java/com/baeldung/jackson/deserialization/jsongeneric/JsonResponse.java
 create mode 100644 jackson-modules/jackson-core/src/main/java/com/baeldung/jackson/deserialization/jsongeneric/User.java
 create mode 100644 jackson-modules/jackson-core/src/test/java/com/baeldung/jackson/deserialization/jsongeneric/GenericTypeDeserializerUnitTest.java

diff --git a/jackson-modules/jackson-core/src/main/java/com/baeldung/jackson/deserialization/jsongeneric/JsonResponse.java b/jackson-modules/jackson-core/src/main/java/com/baeldung/jackson/deserialization/jsongeneric/JsonResponse.java
new file mode 100644
index 0000000000..14f6b3f8ad
--- /dev/null
+++ b/jackson-modules/jackson-core/src/main/java/com/baeldung/jackson/deserialization/jsongeneric/JsonResponse.java
@@ -0,0 +1,14 @@
+package com.baeldung.jackson.deserialization.jsongeneric;
+
+public class JsonResponse<T> {
+
+    private T result;
+
+    public T getResult() {
+        return result;
+    }
+
+    public void setResult(T result) {
+        this.result = result;
+    }
+}
diff --git a/jackson-modules/jackson-core/src/main/java/com/baeldung/jackson/deserialization/jsongeneric/User.java b/jackson-modules/jackson-core/src/main/java/com/baeldung/jackson/deserialization/jsongeneric/User.java
new file mode 100644
index 0000000000..1efb3af7f9
--- /dev/null
+++ b/jackson-modules/jackson-core/src/main/java/com/baeldung/jackson/deserialization/jsongeneric/User.java
@@ -0,0 +1,33 @@
+package com.baeldung.jackson.deserialization.jsongeneric;
+
+public class User {
+
+    private Long id;
+    private String firstName;
+    private String lastName;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public void setFirstName(String firstName) {
+        this.firstName = firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public void setLastName(String lastName) {
+        this.lastName = lastName;
+    }
+}
+
diff --git a/jackson-modules/jackson-core/src/test/java/com/baeldung/jackson/deserialization/jsongeneric/GenericTypeDeserializerUnitTest.java b/jackson-modules/jackson-core/src/test/java/com/baeldung/jackson/deserialization/jsongeneric/GenericTypeDeserializerUnitTest.java
new file mode 100644
index 0000000000..24baeb7f1f
--- /dev/null
+++ b/jackson-modules/jackson-core/src/test/java/com/baeldung/jackson/deserialization/jsongeneric/GenericTypeDeserializerUnitTest.java
@@ -0,0 +1,40 @@
+package com.baeldung.jackson.deserialization.jsongeneric;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.JavaType;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class GenericTypeDeserializerUnitTest {
+
+    ObjectMapper objectMapper = new ObjectMapper();
+
+    @Test
+    void givenJsonObject_whenDeserializeIntoGenericTypeByTypeReference_thenCorrect() throws JsonProcessingException {
+        String json = "{\"result\":{\"id\":1,\"firstName\":\"John\",\"lastName\":\"Lewis\"}}";
+
+        TypeReference<JsonResponse<User>> typeRef = new TypeReference<JsonResponse<User>>() {};
+        JsonResponse<User> jsonResponse = objectMapper.readValue(json, typeRef);
+        User user = jsonResponse.getResult();
+
+        assertThat(user.getId()).isEqualTo(1);
+        assertThat(user.getFirstName()).isEqualTo("John");
+        assertThat(user.getLastName()).isEqualTo("Lewis");
+    }
+
+    @Test
+    void givenJsonObject_whenDeserializeIntoGenericTypeByJavaType_thenCorrect() throws JsonProcessingException {
+        String json = "{\"result\":{\"id\":1,\"firstName\":\"John\",\"lastName\":\"Lewis\"}}";
+
+        JavaType javaType = objectMapper.getTypeFactory().constructParametricType(JsonResponse.class, User.class);
+        JsonResponse<User> jsonResponse = objectMapper.readValue(json, javaType);
+        User user = jsonResponse.getResult();
+
+        assertThat(user.getId()).isEqualTo(1);
+        assertThat(user.getFirstName()).isEqualTo("John");
+        assertThat(user.getLastName()).isEqualTo("Lewis");
+    }
+}
\ No newline at end of file