Spring Boot - deserializing Object inside list of objects

Question

I have an object as question. Inside the question object i am having the list of topic. When i am trying to post a request for this controller i am getting as list of topic as empty. I tried to validate the swagger user interface i couldn't able to see any arguments inside list.

Question.java

import java.io.Serializable;
import java.util.Date;
import java.util.List; 
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;
import javax.validation.constraints.NotNull; 
import org.hibernate.annotations.CreationTimestamp; 
@Entity
public class Question implements Serializable { 
@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE)
@Column(name="questionId")
private Integer questionId;

@NotNull
@Column(name="title")
private String title;

@NotNull
@Column(name="body")
private String body;

@CreationTimestamp
private Date createdAt;

@CreationTimestamp
private Date modifiedAt;

@OneToOne
@JoinColumn(name="userId")
private User userId;

@OneToMany(cascade=CascadeType.ALL)
@JoinColumn(name="question_id")
private List<Comment> commentList;

@ManyToMany(cascade=CascadeType.ALL)  
@JoinTable(name="Question_topic", 
joinColumns=@JoinColumn(name="question_id"), 
inverseJoinColumns=@JoinColumn(name="topic_id"))
private List<Topic> topicList;


/**
 * @return the questionId
 */
public Integer getQuestionId() {
    return questionId;
}

/**
 * @param questionId the questionId to set
 */
public void setQuestionId(Integer questionId) {
    this.questionId = questionId;
}

/**
 * @return the title
 */
public String getTitle() {
    return title;
}

/**
 * @param title the title to set
 */
public void setTitle(String title) {
    this.title = title;
}

/**
 * @return the body
 */
public String getBody() {
    return body;
}

/**
 * @param body the body to set
 */
public void setBody(String body) {
    this.body = body;
}

/**
 * @return the createdAt
 */
public Date getCreatedAt() {
    return createdAt;
}

/**
 * @param createdAt the createdAt to set
 */
public void setCreatedAt(Date createdAt) {
    this.createdAt = createdAt;
}

/**
 * @return the modifiedAt
 */
public Date getModifiedAt() {
    return modifiedAt;
}

/**
 * @param modifiedAt the modifiedAt to set
 */
public void setModifiedAt(Date modifiedAt) {
    this.modifiedAt = modifiedAt;
}

/**
 * @return the userId
 */
public User getUserId() {
    return userId;
}

/**
 * @param userId the userId to set
 */
public void setUserId(User userId) {
    this.userId = userId;
}

/**
 * @return the commentList
 */
public List<Comment> getCommentList() {
    return commentList;
}

/**
 * @param commentList the commentList to set
 */
public void setCommentList(List<Comment> commentList) {
    this.commentList = commentList;
}

public List<Topic> getTopicList() {
    return topicList;
}

public void setTopicList(List<Topic> topicList) {
    this.topicList = topicList;
}

}

Topic.java

 import java.io.Serializable;
 import java.util.Date; 
 import javax.persistence.Column;
 import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
 import javax.persistence.Id;
 import javax.persistence.JoinColumn;
 import javax.persistence.OneToOne;

import org.hibernate.annotations.CreationTimestamp;

@Entity public class Topic implements Serializable {

/**
 * 
 */
private static final long serialVersionUID = 1L;

@Id
@GeneratedValue(strategy=GenerationType.SEQUENCE)
@Column
private Integer topicId;

@Column
private String topicName;

@Column
private String topicDesc;

@CreationTimestamp
private Date createdAt;

@OneToOne
@JoinColumn(name="userId",insertable=false,updatable=false)
private User userId;



/**
 * @return the topicId
 */
public Integer getTopicId() {
    return topicId;
}

/**
 * @param topicId the topicId to set
 */
public void setTopicId(Integer topicId) {
    this.topicId = topicId;
}

/**
 * @return the topicName
 */
public String getTopicName() {
    return topicName;
}

/**
 * @param topicName the topicName to set
 */
public void setTopicName(String topicName) {
    this.topicName = topicName;
}

/**
 * @return the topicDesc
 */
public String getTopicDesc() {
    return topicDesc;
}

/**
 * @param topicDesc the topicDesc to set
 */
public void setTopicDesc(String topicDesc) {
    this.topicDesc = topicDesc;
}

/**
 * @return the createdAt
 */
public Date getCreatedAt() {
    return createdAt;
}

/**
 * @param createdAt the createdAt to set
 */
public void setCreatedAt(Date createdAt) {
    this.createdAt = createdAt;
}

/**
 * @return the userId
 */
public User getUserId() {
    return userId;
}

/**
 * @param userId the userId to set
 */
public void setUserId(User userId) {
    this.userId = userId;
}

}

Spring Boot Class

@RestController
@RequestMapping("/qna/")
public class controller{
   public ResponseEntity<?> postQuestion(@RequestBody Question){
  }
 }

Swagger-UI requested object

{
   "title": "abc",
   "topicList": []
}

Expected request

{
   "title": "abc",
   "topicList": [
         {
            "topicName": "topic1",
            "createdAt": ""
         }
      ]
}

Answer 1

It's missing getters/setters methods on each field.

@Entity
public class Question implements Serializable { 

   private String title;
   private List<Topic> topicList;

   public String getTitle() {
       return title;
   }

   public void setTitle(String title) {
       this.title = title;
   }

   public List<Topic> getTopicList() {
       return topicList;
   }

   public void setTopicList(List<Topic> topicList) {
       this.topicList = topicList;
   }
}


public class Topic implements Serializable {

    private String topicName;
    private Date createdAt;

    public String getTopicName() {
        return topicName;
    }

    public void setTopicName(String topicName) {
        this.topicName = topicName;
    }

    public Date getCreatedAt() {
        return createdAt;
    }

    public void setCreatedAt(Date createdAt) {
        this.createdAt = createdAt;
    }
}

Answer 2

You just don't have getter and setter methods, so if you're going to do a return of data in spring MVC, and you're going to transfer objects that you define yourself, then you should add getter and setter methods for injection into spring MVC, just like that

@Entity
public class Question implements Serializable { 

    private String title;
    private List<Topic> topicList;

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public List<Topic> getTopicList() {
        return topicList;
    }

    public void setTopicList(List<Topic> topicList) {
        this.topicList = topicList;
    }
}

Do you understand?