序列化已经有了id的POJO（java.lang.String） [英] Serializing Already had POJO for id (java.lang.String)

问题描述

我有两个实体，我使用spring framework 4.2.5 + jacksonjson 2.7.5序列化并发送给客户端。我的实体如下：

  @Entity 
 @Table（name =entrada）
 @ JsonIdentityInfo（generator = ObjectIdGenerators.PropertyGenerator.class，property =idEntrada）
 public class EntradaTest实现Serializable {
 private static final long serialVersionUID = 1L; 
 
 @Id 
 @Column（name =id_entrada，unique = true，nullable = false）
 private String idEntrada; 
 
 @Column（nullable = false，length = 5）
 private String codigo; 
 
 private Integer recibidos; 
 
 @ManyToOne 
 @JsonIdentityReference（alwaysAsId = true）
 @JsonIdentityInfo（generator = ObjectIdGenerators.PropertyGenerator.class，property =idEmpleado，scope = Empleado.class）
 @JoinColumn（name =id_pesador_bruto）
 private Empleado pesadorBruto; 
 
 @ManyToOne 
 @JsonIdentityReference（alwaysAsId = true）
 @JsonIdentityInfo（generator = ObjectIdGenerators.PropertyGenerator.class，property =dEmpleado，scope = Empleado.class）
 @JoinColumn（name =id_pesador_tara）
 private Empleado pesadorTara; 
 
 @ManyToOne 
 @JsonIdentityReference（alwaysAsId = true）
 @JsonIdentityInfo（generator = ObjectIdGenerators.PropertyGenerator.class，property =idEmpleado，scope = Empleado.class）
 @JoinColumn（name =id_representante_bruto）
 private Empleado representanteBruto; 
 
 @ManyToOne 
 @JsonIdentityReference（alwaysAsId = true）
 @JsonIdentityInfo（generator = ObjectIdGenerators.PropertyGenerator.class，property =idEmpleado，scope = Empleado.class）
 @JoinColumn（name =id_representante_tara）
 private Empleado representanteTara; 
 
 @ManyToOne 
 @JoinColumn（name =id_oficina，nullable = false）
 private Entidad oficina; 
} 
 
 @Entity 
 @Table（name =empleado）
 @JsonIdentityInfo（generator = ObjectIdGenerators.PropertyGenerator.class，property =idEmpleado，scope = Empleado.class）
类Empleadoest实现Serializable {
 private static final long serialVersionUID = 1L; 
 
 @Id 
 @Column（name =id_empleado，unique = true，nullable = false）
 private String idEmpleado; 
 
 @Column（nullable = false，length = 125）
 private String nombre; 
 
 @OneToMany（mappedBy =pesadorBruto）
 private Set< Entrada> entradasPesadorBruto; 
 
 @OneToMany（mappedBy =pesadorTara）
 private Set< Entrada> entradasPesadorTara; 
 
 @OneToMany（mappedBy =representanteBruto）
 private Set< Entrada> entradasRepresentanteBruto; 
 
 @OneToMany（mappedBy =representanteTara）
 private Set< Entrada> entradasRepresentanteTara; 
} 
  

我的REST服务端点是

  @RequestMapping（value =/ entradas / {id}，method = RequestMethod.GET，produce = MediaType.APPLICATION_JSON_VALUE）
 public ResponseEntity< Entrada> getEntrada（@PathVariable（id）String idEntrada）{
 Entrada entrada = entradaService.get（idEntrada）; 
 if（entrada == null）{
返回新的ResponseEntity< Entrada>（HttpStatus.NOT_FOUND）; 
} 
返回新的ResponseEntity< Entrada>（entrada，HttpStatus.OK）; 
} 
 
 @RequestMapping（value =/ entradas /，method = RequestMethod.POST）
 public ResponseEntity< Void> createEntrada（@RequestBody Entrada entrada，UriComponentsBuilder ucBuilder）{
 
 entradaService.save（entrada）; 
 
 HttpHeaders headers = new HttpHeaders（）; 
 headers.setLocation（ucBuilder.path（/ entradas / {id}）。buildAndExpand（entrada.getIdEntrada（））。toUri（））; 
返回新的ResponseEntity< Void>（标题，HttpStatus.CREATED）; 
} 
  

我发送给客户端的序列化数据如下：

  {
idEntrada：e375ecf9-dabd-4c76-8813-0679818f9590，
codigo：378 -2，
recibidos：0，
pesadorBruto：0c23c490-a54a-495d-9447-dc6227520646，
pesadorTara：874dfe26-11cb-48e4-916e -bf8a83187dcb，
representanteBruto：5fb567af-805a-40dc-84bc-8f6038d8cd2f，
representanteTara：5fb567af-805a-40dc-84bc-8f6038d8cd2f，
oficina ：{
idEntidad：f3964add-3ae8-4392-bafc-cffb9643ec15，
nombre：OPC，
}，
} 
  

但是当我尝试按照以下方式将数据发送回服务器以创建新实体时

  {
idEntrada：e375ecf9-dabd-4c76-8813-0679818f9590，
codigo：378-2 ，
pesadorBruto：{
idEmpleado：0c23c490-a54a-495d-9447-dc6227520646，
nombre：J。CABRERA，
} ，
pesadorTara：{
idEmpleado：874dfe26-11cb-48e4-916 e-bf8a83187dcb，
nombre：L。 A. DELGADO，
}，
representanteBruto：{
idEmpleado：5fb567af-805a-40dc-84bc-8f6038d8cd2f，
nombre：C 。 MARQUEZ，
}，
representanteTara：{
idEmpleado：5fb567af-805a-40dc-84bc-8f6038d8cd2f，
nombre：C。 MARQUEZ，
}，
oficina：{
idEntidad：f3964add-3ae8-4392-bafc-cffb9643ec15，
nombre：OPC， 
}，
} 
  

杰克逊失败：

 无法读取HTTP消息：org.springframework.http.converter.HttpMessageNotReadableException：
无法读取文档：已经有用于id的POJO（java。 lang.String）
 [[ObjectId：key = 5fb567af-805a-40dc-84bc-8f6038d8cd2f，
 type = com.fasterxml.jackson.databind.deser.impl.PropertyBasedObjectIdGenerator，
 scope = lt.ciader.model.Empleado]] 
（通过参考链：lt.ciader.model.Entrada [representanteTara]  - > lt.ciader.model.Empleado [idEmpleado]）; 
嵌套异常是com.fasterxml.jackson.databind.JsonMappingException：
已经有id的POJO（java.lang.String）
 [[ObjectId：key = 5fb567af-805a-40dc-84bc-8f6038d8cd2f， 
 type = com.fasterxml.jackson.databind.deser.impl.PropertyBasedObjectIdGenerator，
 scope = lt.ciader.model.Empleado]] 
（通过参考链：lt.ciader.model.Entrada [representanteTara]  - > lt.ciader.model.Empleado [idEmpleado]）
  

我知道代表塔拉是同一个代表布鲁托，但它可以是我的模型相同的就业，甚至pesadorTara和PesadorBruto也是如此。

当我使用不同的empleados发送数据时，我的服务获取数据并将其序列化而没有问题。
我用谷歌搜索找到解决方案，但我找不到能帮助我的答案。我查看：

JsonMappingException：已经有了POJO for id

Jackson已经有了POJO用于​​身份证明

Spring Rest错误第二次使用子属性保存Object，第二次引用同一个父：已经有POJO for id

https://groups.google.com/forum/#!topic/jackson-user/TSloBi1C_qk

https://github.com/edwinquaihoi/jsonidentitymanytomany/issues/1

https://github.com/ FasterXML / jackson-databind / issues / 266

我做错了什么。我该如何解决这个问题。

解决方案

经过多次测试后我找到了解决方案。问题是杰克逊失败了因为同一个实体出现了两次。该解决方案仅发送secon实例中的普通ID，而不包含在对象中：

  {
idEntrada ：e375ecf9-dabd-4c76-8813-0679818f9590，
codigo：378-2，
pesadorBruto：{
idEmpleado：0c23c490-a54a-495d -9447-dc6227520646，
nombre：J。CABRERA，
}，
pesadorTara：{
idEmpleado：874dfe26-11cb-48e4- 916e-bf8a83187dcb，
nombre：LA DELGADO，
}，
representanteBruto：{
idEmpleado：5fb567af-805a-40dc-84bc- 8f6038d8cd2f，
nombre：C。MARQUEZ，
}，
  

< blockquote>

representanteTara：5fb567af-805a-40dc-84bc-8f6038d8cd2f，

 oficina：{
idEntidad：f3964add-3ae8-4392-bafc-cffb9643ec15，
 nombre：OPC，
}，
} 
  

I have two entities i serialized and send to client using spring framework 4.2.5 + jacksonjson 2.7.5. My entities are the following:

@Entity
@Table(name = "entrada")
@JsonIdentityInfo(generator=ObjectIdGenerators.PropertyGenerator.class, property="idEntrada")
public class EntradaTest implements Serializable {
private static final long serialVersionUID = 1L;

@Id
@Column(name = "id_entrada", unique = true, nullable = false)
private String idEntrada;

@Column(nullable = false, length = 5)
private String codigo;

private Integer recibidos;

@ManyToOne
@JsonIdentityReference(alwaysAsId = true)
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "idEmpleado", scope = Empleado.class)
@JoinColumn(name = "id_pesador_bruto")
private Empleado pesadorBruto;

@ManyToOne
@JsonIdentityReference(alwaysAsId = true)
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "dEmpleado", scope = Empleado.class)
@JoinColumn(name = "id_pesador_tara")
private Empleado pesadorTara;

@ManyToOne
@JsonIdentityReference(alwaysAsId = true)
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "idEmpleado", scope = Empleado.class)
@JoinColumn(name = "id_representante_bruto")
private Empleado representanteBruto;

@ManyToOne
@JsonIdentityReference(alwaysAsId = true)
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "idEmpleado", scope = Empleado.class)
@JoinColumn(name = "id_representante_tara")
private Empleado representanteTara;

@ManyToOne
@JoinColumn(name = "id_oficina", nullable = false)
private Entidad oficina;
}

@Entity
@Table(name = "empleado")
@JsonIdentityInfo(generator=ObjectIdGenerators.PropertyGenerator.class, property="idEmpleado", scope = Empleado.class)
class Empleadoest implements Serializable {
private static final long serialVersionUID = 1L;

@Id
@Column(name = "id_empleado", unique = true, nullable = false)
private String idEmpleado;

@Column(nullable = false, length = 125)
private String nombre;

@OneToMany(mappedBy = "pesadorBruto")
private Set<Entrada> entradasPesadorBruto;

@OneToMany(mappedBy = "pesadorTara")
private Set<Entrada> entradasPesadorTara;

@OneToMany(mappedBy = "representanteBruto")
private Set<Entrada> entradasRepresentanteBruto;

@OneToMany(mappedBy = "representanteTara")
private Set<Entrada> entradasRepresentanteTara;
}

My REST service end points are

@RequestMapping(value = "/entradas/{id}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<Entrada> getEntrada(@PathVariable("id") String idEntrada) {
Entrada entrada = entradaService.get(idEntrada);
if (entrada == null) {
return new ResponseEntity<Entrada>(HttpStatus.NOT_FOUND);
}
return new ResponseEntity<Entrada>(entrada, HttpStatus.OK);
}

@RequestMapping(value = "/entradas/", method = RequestMethod.POST)
public ResponseEntity<Void> createEntrada(@RequestBody Entrada entrada, UriComponentsBuilder ucBuilder) {

entradaService.save(entrada);

HttpHeaders headers = new HttpHeaders();
headers.setLocation(ucBuilder.path("/entradas/{id}").buildAndExpand(entrada.getIdEntrada()).toUri());
return new ResponseEntity<Void>(headers, HttpStatus.CREATED);
}

The serialized data I send to the client looks like:

{
"idEntrada": "e375ecf9-dabd-4c76-8813-0679818f9590",
"codigo": "378-2",
"recibidos": 0,
"pesadorBruto": "0c23c490-a54a-495d-9447-dc6227520646",
"pesadorTara": "874dfe26-11cb-48e4-916e-bf8a83187dcb",
"representanteBruto": "5fb567af-805a-40dc-84bc-8f6038d8cd2f",
"representanteTara": "5fb567af-805a-40dc-84bc-8f6038d8cd2f",
"oficina": {
"idEntidad": "f3964add-3ae8-4392-bafc-cffb9643ec15",
"nombre": "O.P.C.",
},
}

But when i try to send data back to the server as following to create a new entity

{
"idEntrada":"e375ecf9-dabd-4c76-8813-0679818f9590",
"codigo":"378-2",
"pesadorBruto":{
"idEmpleado":"0c23c490-a54a-495d-9447-dc6227520646",
"nombre":"J. CABRERA",
},
"pesadorTara":{
"idEmpleado":"874dfe26-11cb-48e4-916e-bf8a83187dcb",
"nombre":"L. A. DELGADO",
},
"representanteBruto":{
"idEmpleado":"5fb567af-805a-40dc-84bc-8f6038d8cd2f",
"nombre":"C. MARQUEZ",
},
"representanteTara":{
"idEmpleado":"5fb567af-805a-40dc-84bc-8f6038d8cd2f",
"nombre":"C. MARQUEZ",
},
"oficina":{
"idEntidad":"f3964add-3ae8-4392-bafc-cffb9643ec15",
"nombre":"O.P.C.",
},
}

Jackson fails:

Failed to read HTTP message: org.springframework.http.converter.HttpMessageNotReadableException:
Could not read document: Already had POJO for id (java.lang.String)
[[ObjectId: key=5fb567af-805a-40dc-84bc-8f6038d8cd2f,
type=com.fasterxml.jackson.databind.deser.impl.PropertyBasedObjectIdGenerator,
scope=lt.ciader.model.Empleado]]
(through reference chain: lt.ciader.model.Entrada["representanteTara"]->lt.ciader.model.Empleado["idEmpleado"]);
nested exception is com.fasterxml.jackson.databind.JsonMappingException:
Already had POJO for id (java.lang.String)
[[ObjectId: key=5fb567af-805a-40dc-84bc-8f6038d8cd2f,
type=com.fasterxml.jackson.databind.deser.impl.PropertyBasedObjectIdGenerator,
scope=lt.ciader.model.Empleado]]
(through reference chain: lt.ciader.model.Entrada["representanteTara"]->lt.ciader.model.Empleado["idEmpleado"])

I know that representanteTara is the same sa representateBruto but it can be the same employment acoording to my model, even pesadorTara and PesadorBruto too.

When i send data with differents empleados my service get data and serialized it without problems. I googled to find a solution but i can't find an answer that help me. I review:

JsonMappingException: Already had POJO for id

Jackson Already had POJO for id

Spring Rest error the second time that saves Object with child properties that references the same father the second time: Already had POJO for id

https://groups.google.com/forum/#!topic/jackson-user/TSloBi1C_qk

https://github.com/edwinquaihoi/jsonidentitymanytomany/issues/1

https://github.com/FasterXML/jackson-databind/issues/266

What i doing wrong. How can I solve the problem.

解决方案

After many test I found a solution. The problem is that Jackson fails becouse the same entity is present two times. The solution is send only the plain ID in the secon instance, not wrapped in object:

{
"idEntrada":"e375ecf9-dabd-4c76-8813-0679818f9590",
"codigo":"378-2",
"pesadorBruto":{
"idEmpleado":"0c23c490-a54a-495d-9447-dc6227520646",
"nombre":"J. CABRERA",
},
"pesadorTara":{
"idEmpleado":"874dfe26-11cb-48e4-916e-bf8a83187dcb",
"nombre":"L. A. DELGADO",
},
"representanteBruto":{
"idEmpleado":"5fb567af-805a-40dc-84bc-8f6038d8cd2f",
"nombre":"C. MARQUEZ",
},

"representanteTara": "5fb567af-805a-40dc-84bc-8f6038d8cd2f",

"oficina":{
"idEntidad":"f3964add-3ae8-4392-bafc-cffb9643ec15",
"nombre":"O.P.C.",
},
}

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