当我尝试反序列化一个具有多态成员的实体时,Jackson会抛出com.fasterxml.jackson.databind.JsonMappingException异常,并抱怨缺少类型信息(...而实际上该信息在JSON中是存在的->请参考示例)。
为了确认所有东西都正常工作,我已经设置了一个测试...
有趣的是,我可以将猫作为宠物创建我的家,但当我想要更新猫的名字时,它无法反序列化JSON了... 有什么建议吗?
Unexpected token (END_OBJECT), expected FIELD_NAME: missing property '@class' that is to contain type id (for class demo.animal.Animal)\n at [Source: N/A; line: -1, column: -1] (through reference chain: demo.home.Home[\"pet\"])"
所有实际工作都由Spring HATEOAS的PagingAndSortingRepository完成。
我使用的是spring-boot V 1.2.4.RELEASE版本,这意味着jackson是V 2.4.6版本,Spring HATEOAS是V 0.16.0.RELEASE版本。
示例:
我家里有一只宠物:
@Entity
public class Home {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int id;
@OneToOne(cascade = {CascadeType.ALL})
private Animal pet;
public Animal getPet() {
return pet;
}
public void setPet(Animal pet) {
this.pet = pet;
}
}
那个宠物是一种动物 - 在这种情况下可能是猫或狗。它的类型由@class属性确定...
@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "@class")
public abstract class Animal {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private int id;
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
@Entity
public class Cat extends Animal {
}
@Entity
public class Dog extends Animal {
}
还有这个方便的PagingAndSortingRepository,它允许我通过REST/HATEOAS访问我的主页...
@RepositoryRestResource(collectionResourceRel = "home", path = "home")
public interface HomeRepository extends PagingAndSortingRepository<Home, Integer> {
}
为了确认所有东西都正常工作,我已经设置了一个测试...
@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = DemoApplication.class)
@WebAppConfiguration
public class HomeIntegrationTest {
@Autowired
private WebApplicationContext ctx;
private MockMvc mockMvc;
@Before
public void setUp() {
this.mockMvc = webAppContextSetup(ctx).build();
}
@Test
public void testRename() throws Exception {
// I create my home with some cat...
// http://de.wikipedia.org/wiki/Schweizerdeutsch#Wortschatz -> Büsi
MockHttpServletRequestBuilder post = post("/home/")
.content("{\"pet\": {\"@class\": \"demo.animal.Cat\", \"name\": \"Büsi\"}}");
mockMvc.perform(post).andDo(print()).andExpect(status().isCreated());
// Confirm that the POST request works nicely, so the JSON thingy is correct...
MockHttpServletRequestBuilder get1 = get("/home/").accept(MediaType.APPLICATION_JSON);
mockMvc.perform(get1).andDo(print()).andExpect(status().isOk())
.andExpect(content().contentTypeCompatibleWith(MediaType.APPLICATION_JSON))
.andExpect(jsonPath("$._embedded.home", hasSize(1)))
.andExpect(jsonPath("$._embedded.home[0].pet.name", is("Büsi")));
// Now the interesting part: let's give that poor kitty a proper name...
MockHttpServletRequestBuilder put = put("/home/1")
.content("{\"pet\": {\"@class\": \"demo.animal.Cat\", \"name\": \"Beauford\"}}");
mockMvc.perform(put).andDo(print()).andExpect(status().isNoContent());
// PUT will thow JsonMappingException exception about an missing "@class"...
MockHttpServletRequestBuilder get2 = get("/home/").accept(MediaType.APPLICATION_JSON);
mockMvc.perform(get2).andDo(print()).andExpect(status().isOk())
.andExpect(content().contentTypeCompatibleWith(MediaType.APPLICATION_JSON))
.andExpect(jsonPath("$._embedded.home", hasSize(1)))
.andExpect(jsonPath("$._embedded.home[0].pet.name", is("Beaufort")));
}
}
有趣的是,我可以将猫作为宠物创建我的家,但当我想要更新猫的名字时,它无法反序列化JSON了... 有什么建议吗?