JDO、org.json.simple.JSONObject 和 PostgreSQL JSON 类型

Question

在我的 PostgreSQL 数据库中，我有：

CREATE TABLE category (
    // ...
    category_name_localization JSON not null,
);

在 Java 中，我有一个 JDO class 像这样：

@javax.jdo.annotations.PersistenceCapable(table = "category" )
public class Category extends _BlueEntity implements Serializable {
    //...

    private org.json.simple.JSONObject category_name_localization;

    @javax.jdo.annotations.Column( name = "category_name_localization" )
    public org.json.simple.JSONObject getCategoryNameLocalization() {
        return category_name_localization;
    }
}

当我使用此 class 时，DataNucleus 给出以下异常：

org.datanucleus.exceptions.NucleusUserException: Field "com.advantagegroup.blue.ui.entity.Category.category_name_localization" is a map that has been specified without a join table and neither the key nor the value has a mapped-by specified. This is invalid!
                at org.datanucleus.store.rdbms.RDBMSStoreManager.newJoinTable(RDBMSStoreManager.java:2720)
                at org.datanucleus.store.rdbms.mapping.java.AbstractContainerMapping.initialize(AbstractContainerMapping.java:82)
                at org.datanucleus.store.rdbms.mapping.MappingManagerImpl.getMapping(MappingManagerImpl.java:680)
                at org.datanucleus.store.rdbms.table.ClassTable.manageMembers(ClassTable.java:518)
                at org.datanucleus.store.rdbms.table.ClassTable.manageClass(ClassTable.java:424)
                at org.datanucleus.store.rdbms.table.ClassTable.initializeForClass(ClassTable.java:1250)
                at org.datanucleus.store.rdbms.table.ClassTable.initialize(ClassTable.java:271)
                at org.datanucleus.store.rdbms.RDBMSStoreManager$ClassAdder.initializeClassTables(RDBMSStoreManager.java:3288)
                at org.datanucleus.store.rdbms.RDBMSStoreManager$ClassAdder.run(RDBMSStoreManager.java:2897)
                at org.datanucleus.store.rdbms.AbstractSchemaTransaction.execute(AbstractSchemaTransaction.java:118)
                at org.datanucleus.store.rdbms.RDBMSStoreManager.manageClasses(RDBMSStoreManager.java:1637)
                at org.datanucleus.store.rdbms.RDBMSStoreManager.getDatastoreClass(RDBMSStoreManager.java:665)
                at org.datanucleus.store.rdbms.RDBMSStoreManager.getPropertiesForGenerator(RDBMSStoreManager.java:2098)
                at org.datanucleus.store.AbstractStoreManager.getStrategyValue(AbstractStoreManager.java:1278)
                at org.datanucleus.ExecutionContextImpl.newObjectId(ExecutionContextImpl.java:3668)
                at org.datanucleus.state.StateManagerImpl.setIdentity(StateManagerImpl.java:2276)
                at org.datanucleus.state.StateManagerImpl.initialiseForPersistentNew(StateManagerImpl.java:482)
                at org.datanucleus.state.StateManagerImpl.initialiseForPersistentNew(StateManagerImpl.java:122)
                at org.datanucleus.state.ObjectProviderFactoryImpl.newForPersistentNew(ObjectProviderFactoryImpl.java:218)
                at org.datanucleus.ExecutionContextImpl.persistObjectInternal(ExecutionContextImpl.java:1986)
                at org.datanucleus.ExecutionContextImpl.persistObjectWork(ExecutionContextImpl.java:1830)
                at org.datanucleus.ExecutionContextImpl.persistObject(ExecutionContextImpl.java:1685)
                at org.datanucleus.api.jdo.JDOPersistenceManager.jdoMakePersistent(JDOPersistenceManager.java:712)
                at org.datanucleus.api.jdo.JDOPersistenceManager.makePersistent(JDOPersistenceManager.java:738)
                at com.advantagegroup.blue.ui.jdo._BlueJdo.insert(_BlueJdo.java:40)
                at ...

这个错误在某种程度上是有道理的，因为 org.json.simple.JSONObject 扩展了 Map。然而，这个字段不是任何关系的一部分——它是 JSON 类型，因此很自然地用 JSONObject

来支持它

我如何告诉 JDO / DataNucleus 以与 String 或 Date 相同的方式冷却和处理 org.json.simple.JSONObject？

谢谢！直流

Answer 1

我对此的理解是，您的默认尝试是尝试保持正常的 Map（因为虽然它不知道 JSONObject 是什么，但它知道 Map 是什么是)，并且对于 RDBMS，它需要一个连接 table。

由于您可能希望 JSONObject 持久化到单个列中，因此您需要创建一个 JDO AttributeConverter。我用我自己的类型做了类似的事情并且工作正常（我在 v5.0.5 IIRC 上）。

我也找到了this in their docs, for when you have your own Map class that it doesn't know how to handle by default in terms of replacing it with a proxy (to intercept the calls to put, putAll etc). If you add that line it will not try to wrap this field with a proxy (which it doesn't know how to do for that type, unless you tell it). If you wanted to auto-detect the JSONObject becoming "dirty" you would need to write a proxy wrapper, as per this page。

这没有回答如何映射该转换器的列以在 PostgreSQL 中使用 "json" 类型，但我猜想如果您设置 sqlType 你可能会在这方面取得成功。

JDO、org.json.simple.JSONObject 和 PostgreSQL JSON 类型

JDO, org.json.simple.JSONObject and PostgreSQL JSON type

postgresql

json

jdo

datanucleus