【发布时间】：2014-08-25 12:05:43
【问题描述】：
我正在构建一个 Spring Data REST 应用程序，当我尝试发布它时遇到了一些问题。主实体嵌套了另外两个相关实体。
有一个“问题”对象有很多答案，每个答案都有很多回复。
我从前端应用程序生成一个这样的 JSON 来发布问题：
{
"user": "http://localhost:8080/users/1",
"status": 1,
"answers": [
{
"img": "urlOfImg",
"question": "http://localhost:8080/question/6",
"replies": [
{
"literal": "http://localhost:8080/literal/1",
"result": "6"
},
{
"literal": "http://localhost:8080/literal/1",
"result": "6"
}
]
},
{
"img": "urlOfImg",
"question": "http://localhost:8080/question/6",
"replies": [
{
"literal": "http://localhost:8080/literal/3",
"result": "10"
}
]
}
]
}
但是当我尝试发布它时，我收到以下错误响应：
{
"cause" : {
"cause" : {
"cause" : null,
"message" : "Template must not be null or empty!"
},
"message" : "Template must not be null or empty! (through reference chain: project.models.Questionary[\"answers\"])"
},
"message" : "Could not read JSON: Template must not be null or empty! (through reference chain: project.models.Questionary[\"answers\"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Template must not be null or empty! (through reference chain: project.models.Questionary[\"answers\"])"
}
编辑：
我还添加了我的存储库：
@RepositoryRestResource(collectionResourceRel = "questionaries", path = "questionaries")
public interface InspeccionRepository extends JpaRepository<Inspeccion, Integer> {
@RestResource(rel="byUser", path="byUser")
public List<Questionary> findByUser (@Param("user") User user);
}
我的实体问题类是：
@Entity @Table(name="QUESTIONARY", schema="enco" )
public class Questionary implements Serializable {
private static final long serialVersionUID = 1L;
//----------------------------------------------------------------------
// ENTITY PRIMARY KEY ( BASED ON A SINGLE FIELD )
//----------------------------------------------------------------------
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SEC_QUESTIONARY")
@SequenceGenerator(name = "SEC_QUESTIONARY", sequenceName = "ENCO.SEC_QUESTIONARY", allocationSize = 1)
@Column(name="IDQUES", nullable=false)
private Integer idques ;
//----------------------------------------------------------------------
// ENTITY DATA FIELDS
//----------------------------------------------------------------------
@Column(name="ESTATUS")
private Integer estatus ;
//----------------------------------------------------------------------
// ENTITY LINKS ( RELATIONSHIP )
//----------------------------------------------------------------------
@ManyToOne
@JoinColumn(name="IDUSER", referencedColumnName="IDUSER")
private User user;
@OneToMany(mappedBy="questionary", targetEntity=Answer.class)
private List<Answer> answers;
//----------------------------------------------------------------------
// CONSTRUCTOR(S)
//----------------------------------------------------------------------
public Questionary()
{
super();
}
//----------------------------------------------------------------------
// GETTERS & SETTERS FOR FIELDS
//----------------------------------------------------------------------
//--- DATABASE MAPPING : IDNSE ( NUMBER )
public void setIdnse( Integer idnse )
{
this.idnse = idnse;
}
public Integer getIdnse()
{
return this.idnse;
}
//--- DATABASE MAPPING : ESTADO ( NUMBER )
public void setEstatus Integer estatus )
{
this.estatus = estatus;
}
public Integer getEstatus()
{
return this.estatus;
}
//----------------------------------------------------------------------
// GETTERS & SETTERS FOR LINKS
//----------------------------------------------------------------------
public void setUser( Usuario user )
{
this.user = user;
}
public User getUser()
{
return this.user;
}
public void setAnswers( List<Respuesta> answers )
{
this.answers = answer;
}
public List<Answer> getAnswers()
{
return this.answers;
}
// Get Complete Object method public List<Answer>
getAnswerComplete() {
List<Answer> answers = this.answers;
return answers;
}
}
我的答案实体：
@Entity @Table(name="ANSWER", schema="enco" ) public class Answer
implements Serializable {
private static final long serialVersionUID = 1L;
//----------------------------------------------------------------------
// ENTITY PRIMARY KEY ( BASED ON A SINGLE FIELD )
//----------------------------------------------------------------------
@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "SEC_ANSWER")
@SequenceGenerator(name = "SEC_ANSWER", sequenceName = "ENCOADMIN.SEC_ANSWER", allocationSize = 1)
@Column(name="IDANS", nullable=false)
private Integer idans ;
//----------------------------------------------------------------------
// ENTITY DATA FIELDS
//----------------------------------------------------------------------
@Column(name="IMG", length=100)
private String img ;
//----------------------------------------------------------------------
// ENTITY LINKS ( RELATIONSHIP )
//----------------------------------------------------------------------
@ManyToOne
@JoinColumn(name="IDQUES", referencedColumnName="IDQUES")
private Questionary questionary ;
@OneToMany(mappedBy="answer", targetEntity=Reply.class)
private List<Reply> replies;
@ManyToOne
@JoinColumn(name="IDQUE", referencedColumnName="IDQUE")
private Question Question ;
//----------------------------------------------------------------------
// CONSTRUCTOR(S)
//----------------------------------------------------------------------
public Answer()
{
super();
}
//----------------------------------------------------------------------
// GETTER & SETTER FOR THE KEY FIELD
//----------------------------------------------------------------------
public void setIdans( Integer idans )
{
this.idans = idans ;
}
public Integer getIdans()
{
return this.idans;
}
//----------------------------------------------------------------------
// GETTERS & SETTERS FOR FIELDS
//----------------------------------------------------------------------
//--- DATABASE MAPPING : IMAGEN ( VARCHAR2 )
public void setImg( String img )
{
this.img = img;
}
public String getImg()
{
return this.img;
}
//----------------------------------------------------------------------
// GETTERS & SETTERS FOR LINKS
//----------------------------------------------------------------------
public void setQuestionary( Questionary questionary )
{
this.questionary = questionary;
}
public Questionary getQuestionary()
{
return this.questionary;
}
public void setReplies( List<Reply> contestaciones )
{
this.replies = replies;
}
public List<Reply> getReplies()
{
return this.replies;
}
public void setQuestion( Question question )
{
this.question = question;
}
public Question getQuestion()
{
return this.question;
}
}
这是错误控制台：
Caused by: com.fasterxml.jackson.databind.JsonMappingException:
Template must not be null or empty! (through reference chain:
project.models.Questionary["answers"]) at
com.fasterxml.jackson.databind.JsonMappingException.wrapWithPath(JsonMappingException.java:232)
~[jackson-databind-2.3.3.jar:2.3.3] at *snip*
【问题讨论】：
-
你能不能也展示你的控制器方法、堆栈跟踪和
POJO类？ -
我已经用您要求的所有信息编辑了主帖。感谢您的帮助。
-
也许问题出在错误的数据中？可以吗：
"question": "http://localhost:8080/question/6"。也许它应该看起来像这样："question": 6。为什么要发送URLs 而不是 id？ -
因为问题和答案之间有关系，所以这部分是可以的，我个人尝试过，没有问题。问题是当我在列表中的另一个中嵌套和对象时。例如，如果我首先做这个帖子，只有检查和每个答案的一个帖子和每个回复的另一个帖子都有效，但是当我有一个超过 350 个答案的问题并且每个问题都有 3 或 4 个回复时，我的事情是荒谬的。 ...它必须是一种在一个嵌套对象中执行此操作的方法...
-
你有想过这个吗？