为什么Spring Data MongoDB无法实例化这种嵌套类型结构？

Question

我的文档结构如下:

{
    _id: "A",
    groups:[{
        groupId: "someId",
        groupName: "someName",
        params: {
            type1: ["a", "b"],
            type2: ["c", d]
        }
    }],
    config: {
        person: {}
        dataDetails: {
            dataTypeDetails: {},
            dataList: ["dt1", "dt2"]
        }
    }
}

我的Spring Data MongoDB模型类型如下所示:

// Imports etc.
@Document
public class Entity {

    @Id
    private String _id;

    private List<Group> groups;
    private Config config;
    // setters and getters

    public class Group {
        private String groupId;
        private String groupName;
        private ParamData params;

        // setter and getters
    }

    public class ParamData {
        private List<String> type1;
        private List<String> type2;
    }

    public class Config {
        private Map person;
        private DataConfig dataDetails;
    }

    public class DataConfig {
        private Map dataTypeDetails;
        private List<String> dataList;
    }
}

堆栈跟踪:

org.springframework.data.mapping.model.MappingInstantiationException: Failed to instantiate com.****.common.models.Entity$ParamData using constructor public com.****.common.models.Entity$ParamData(com.****.common.models.Entity) with arguments com.****.common.models.Entity$Group@2eb61a7b
    at org.springframework.data.convert.ReflectionEntityInstantiator.createInstance(ReflectionEntityInstantiator.java:78)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:257)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:237)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readValue(MappingMongoConverter.java:1136)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.access$100(MappingMongoConverter.java:78)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter$MongoDbPropertyValueProvider.getPropertyValue(MappingMongoConverter.java:1085)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.getValueInternal(MappingMongoConverter.java:816)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter$1.doWithPersistentProperty(MappingMongoConverter.java:270)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter$1.doWithPersistentProperty(MappingMongoConverter.java:263)
    at org.springframework.data.mapping.model.BasicPersistentEntity.doWithProperties(BasicPersistentEntity.java:261)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:263)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:237)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readCollectionOrArray(MappingMongoConverter.java:861)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.readValue(MappingMongoConverter.java:1134)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.access$100(MappingMongoConverter.java:78)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter$MongoDbPropertyValueProvider.getPropertyValue(MappingMongoConverter.java:1085)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.getValueInternal(MappingMongoConverter.java:816)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter$1.doWithPersistentProperty(MappingMongoConverter.java:270)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter$1.doWithPersistentProperty(MappingMongoConverter.java:263)
    at org.springframework.data.mapping.model.BasicPersistentEntity.doWithProperties(BasicPersistentEntity.java:261)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:263)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:237)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:201)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:197)
    at org.springframework.data.mongodb.core.convert.MappingMongoConverter.read(MappingMongoConverter.java:78)
    at org.springframework.data.mongodb.core.MongoTemplate$ReadDbObjectCallback.doWith(MongoTemplate.java:2016)
    at org.springframework.data.mongodb.core.MongoTemplate.executeFindMultiInternal(MongoTemplate.java:1700)
    at org.springframework.data.mongodb.core.MongoTemplate.doFind(MongoTemplate.java:1523)
    at org.springframework.data.mongodb.core.MongoTemplate.doFind(MongoTemplate.java:1507)
    at org.springframework.data.mongodb.core.MongoTemplate.find(MongoTemplate.java:532)
    at org.springframework.data.mongodb.core.MongoTemplate.findOne(MongoTemplate.java:497)
    at org.springframework.data.mongodb.core.MongoTemplate.findOne(MongoTemplate.java:489)

我在DAO中我试图通过标识符获取文档,但它仅对dataDetails和params的值失败.如果我注释掉ParamData参数,我会收到错误DataConfig.数据是使用命令行/节点脚本添加的,未使用此代码添加.但是它可以通过node/mongoose以及命令行正确检索.

Answer 1

这似乎是双嵌套内部类和编译器创建的综合生成构造函数的问题.我可以在本地重现该问题,看看我们是否可以提供修复.在此期间,您有两种选择:

1. 将内部类转换为静态类,因为这将删除合成构造函数并且实例化将正常工作.
2. 嵌套类型声明的方式与嵌套属性的方式相同.即移动ParamData类到Group类,DataConfig到Config因为这将导致它们匹配的实例化为了春天的数据目前依赖的方式创建的合成构造函数.

我建议使用前一种方法,因为它不会人为地将类绑定到外部类的实例.