我试图在SpringBoot中使用mongock开发两个类之间的关系，但无法在这些类之间创建一个单独的关系。
我使用@dbref来建立关系
类别.java

package com.test.model;

import java.util.List;

import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.DBRef;
import org.springframework.data.mongodb.core.mapping.Document;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
@Document("category")
public class Category {

    @Id
    private Integer id;
    private String name; 

    @DBRef
    private List<Requirement> requirements ;    
}

需求.java

package com.test.model;

import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Document("requirements")
public class Requirement {

    @Id
    private int Id;

    private String subcls;

    private String standard;

}

为了在mongodb中存储数据，我使用了以下配置类
数据库更改日志.java

package com.test.config;

import org.bson.Document;

import com.github.cloudyrock.mongock.ChangeLog;
import com.github.cloudyrock.mongock.ChangeSet;
import com.github.cloudyrock.mongock.driver.mongodb.springdata.v3.decorator.impl.MongockTemplate;
import com.mongodb.client.MongoCollection;

import com.test.config.Migration;

@ChangeLog
public class DatabaseChangeLog {

    @ChangeSet(order="001", id="seedDatabase", author="testuser")
    public void seedDatabase(MongockTemplate db) {

        MongoCollection<Document> mycollection = db.getCollection("category");

        for(String json : Migration.Category) {
            mycollection.insertOne(Document.parse(json));
        }
    }

    @ChangeSet(order="002", id="seedDatabase2", author="testuser")
    public void seedDatabaseRequirement(MongockTemplate db) {

        MongoCollection<Document> mycollection = db.getCollection("requirements");

        for(String json : Migration.Requirements) {
            System.out.println(json);
            mycollection.insertOne(Document.parse(json));
        }

   }
}

迁移.java

package com.test.config;

public class Migration {

    public static final String[] Category = {
            "{'_id': 1,'name':'Data Migration'}",
            "{'_id': 2,'name':'Data Recovery'}"
    };

    public static final String[] Requirements = {
             "{'_id': 1, 'subcls': 'sub-class DM', 'standard' : 'DM_Standard','category': {'$ref': 'category', '$id': 1}}",
             "{'_id': 2, 'subcls': 'sub-class DM', 'standard' : 'DM_Standard', 'category': {'$ref': 'category', '$id': 1}}",
             "{'_id': 3, 'subcls': 'sub-class DR', 'standard' : 'DR_Standard', 'category': {'$ref': 'category', '$id': 2}}"
    };
}

应用程序属性

spring.data.mongodb.host=localhost
spring.data.mongodb.port=27017
spring.data.mongodb.database=testdb

mongock.change-logs-scan-package=com.test.config

从上面的代码，我已经能够创建数据库及其集合，即类别和要求
问题是当我试图在 Package 类的帮助下调用@restcontroller时。我想从api中获取类别数据以及相应的需求数据。
categorycontroller.java包com.test.controller；

import java.util.ArrayList;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.test.model.Category;
import com.test.model.Requirement;
import com.test.CategoryRepository;

@RestController
@RequestMapping("/api")
public class CategoryController {

    @Autowired
    private CategoryRepository catRepo;

    @GetMapping(value="/categories", produces={"application/json"})
    public Iterable<CategoryGet> getAllCategories() {

        Iterable<Category> categories =  catRepo.findAll();

        List<CategoryGet> gets = new ArrayList<CategoryGet>();

        for(Category category: categories) {
            gets.add( new CategoryGet(category) );
        }

        return gets;
    }
}

Package 类
分类

package com.test.controller;

import java.util.ArrayList;
import java.util.List;

import com.test.model.Category;
import com.test.model.Requirement;

public class CategoryGet implements java.io.Serializable {

    private int id;
    private String name;
    private List<RequirementGet> requirements = new ArrayList<RequirementGet>();

    public CategoryGet() {

    }

    public CategoryGet(Category cat) {
        this.name = cat.getName();
        for(Requirement req: cat.getRequirements()) {
            this.requirements.add(new RequirementGet(req));
        }
    }

    public String getName() {
        return name;
    }

    public List<RequirementGet> getRequirements() {
        return requirements;
    }

}

需求获取.java

package com.test.controller;

import com.test.model.Requirement;

public class RequirementGet implements java.io.Serializable{

    private int id;

    private String subcls;

    private String standard;

    private String category;

    public RequirementGet() {}

    public RequirementGet(Requirement req) {
        super();
        this.id = req.getId();
        this.subcls = req.getSubcls();
        this.standard = req.getStandard();
    }

    public int getId() {
        return id;
    }

    public String getSubcls() {
        return subcls;
    }

    public String getStandard() {
        return standard;
    }   
}

在我得到的错误之后
在此处输入图像描述
相应类别的要求为空。
如果需要其他信息，请务必告诉我。