如何使用Spring Data REST POST嵌套实体 [英] How to POST nested entities with Spring Data REST
本文介绍了如何使用Spring Data REST POST嵌套实体的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在构建一个Spring Data REST应用程序，当我尝试POST它时遇到了一些问题。主实体有另外两个嵌套的相关实体。
I'm building a Spring Data REST application and I'm having some problems when I try to POST it. The main entity has other two related entities nested.
有一个问号对象有很多答案，每个答案都有很多回复。
There is a "questionary" object which has many answers and each one of these answers have many replies.
我从前端应用程序生成一个类似这样的JSON来POST问题：
I generate a JSON like this from the front application to POST the questionary:
{
"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"
}
]
}
]
}
但是当我尝试发布时，我收到以下错误回复：
But when I try to post it, I get the follow error response:
{
"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：
I also add my repository:
@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*
推荐答案
尝试在类<$ c $中的字段 answers 上添加 @RestResource（exported = false） c>质疑。
Try adding @RestResource(exported = false) on field answers in class Questionary.
据我所知，出现此错误是因为反序列化器需要URI来获取答案，而不是嵌套答案在JSON中。添加注释会让它看起来更像JSON。
According to me, this error occurs because the deserializer expects URIs to fetch the answers from, instead of having the answers nested in the JSON. Adding the annotation tells it to look in JSON instead.
这篇关于如何使用Spring Data REST POST嵌套实体的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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