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ISIS:Blob/Clob 字段序列化存在问题



编辑：解决方案： 升级到ISIS 1.17.0并设置属性isis.persistor.datanucleus.standaloneCollection.bulkLoad=false解决了前两个问题。

我正在使用Apache ISIS 1.16.2，并尝试将Blob/Clob内容存储在MariaDB数据库(v10.1.35)中。因此，我使用数据库连接器org.mariadb.jdbc.mariadb-java-client(v2.3.0) 和代码中的@Persistent注释，如许多示例和 ISIS 文档所示。

使用下面的代码，我只得到一个名为content_name的单个列(其中 Blob 对象以二进制形式序列化)，而不是content_name、content_mimetype和content_bytes三列。

这是具有 Blob字段content的文档类：

@PersistenceCapable(identityType = IdentityType.DATASTORE)
@DatastoreIdentity(strategy = IdGeneratorStrategy.IDENTITY, column = "id")
@DomainObject(editing = Editing.DISABLED, autoCompleteRepository = DocumentRepository.class, objectType = "Document")
@Getter
// ...
public class Document implements Comparable<Document> {
@Persistent(
defaultFetchGroup = "false",
columns = {
@Column(name = "content_name"),
@Column(name = "content_mimetype"),
@Column(name = "content_bytes",
jdbcType = "BLOB",
sqlType = "LONGVARBINARY")
})
@Nonnull
@Column(allowsNull = "false")
@Property(optionality = Optionality.MANDATORY)
private Blob content;
// ...
@Column(allowsNull = "false")
@Property
private Date created = new Date();
public Date defaultCreated() {
return new Date();
}
@Column(allowsNull = "true")
@Property
@Setter
private String owner;
// ...
}

这将为 DomainObject 类Document创建以下架构，其中 Blob 字段只有一列：

CREATE TABLE `document` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`content_name` mediumblob,
`created` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`owner` varchar(255) CHARACTER SET latin1 COLLATE latin1_bin DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

通常，ISIS框架的类org.apache.isis.objectstore.jdo.datanucleus.valuetypes.IsisBlobMapping应该进行映射。但似乎这个映射器不知何故没有参与......

1. 问题：如何将 Blob 字段拆分为三列(如上所述和许多演示项目)。即使我切换到 HSQLDB，我仍然只得到一列，所以这可能不是 MariaDB 的问题。

2. 问题：如果我在继承自另一个 DomainObject 类的类中使用 Blob/Clob 字段，我经常会得到一个org.datanucleus.exceptions.NucleusException(堆栈跟踪见下文)，并且我无法对其进行正面或反面。处理继承时有哪些潜在的陷阱？为什么我会收到此异常？

3. 问题：我需要存储属于域对象的文档(您可能已经猜到了)。正确的方法是将文档存储在文件系统树而不是数据库中(默认情况下，数据库对对象数据也有一些大小限制)并引用对象中的文件。在Datanucleus文档中，我找到了应该完全做到这一点的扩展serializeToFileLocation。我尝试通过将行@Extension(vendorName="datanucleus", key="serializeToFileLocation" value="document-repository")添加到 Blob 字段来尝试，但没有任何反应。所以我的问题是：这个Datanucleus扩展是否与Apache Isis兼容？

如果此扩展与 Isis 冲突，是否可以在将域对象保存到数据库并在加载之前还原它之前，使用javax.jdo.listener.StoreLifecycleListener或org.apache.isis.applib.AbstractSubscriber将 Blob 存储在文件系统上？有更好的解决方案吗？

现在就是这样。提前谢谢你！;-)

堆栈跟踪到问题 2：

... (other Wicket related stack trace)
Caused by: org.datanucleus.exceptions.NucleusException: Creation of SQLExpression for mapping "org.datanucleus.store.rdbms.mapping.java.SerialisedMapping" caused error
at org.datanucleus.store.rdbms.sql.expression.SQLExpressionFactory.newExpression(SQLExpressionFactory.java:199)
at org.datanucleus.store.rdbms.sql.expression.SQLExpressionFactory.newExpression(SQLExpressionFactory.java:155)
at org.datanucleus.store.rdbms.request.LocateBulkRequest.getStatement(LocateBulkRequest.java:158)
at org.datanucleus.store.rdbms.request.LocateBulkRequest.execute(LocateBulkRequest.java:283)
at org.datanucleus.store.rdbms.RDBMSPersistenceHandler.locateObjects(RDBMSPersistenceHandler.java:564)
at org.datanucleus.ExecutionContextImpl.findObjects(ExecutionContextImpl.java:3313)
at org.datanucleus.api.jdo.JDOPersistenceManager.getObjectsById(JDOPersistenceManager.java:1850)
at org.apache.isis.core.runtime.system.persistence.PersistenceSession.loadPersistentPojos(PersistenceSession.java:1010)
at org.apache.isis.core.runtime.system.persistence.PersistenceSession.adaptersFor(PersistenceSession.java:1603)
at org.apache.isis.core.runtime.system.persistence.PersistenceSession.adaptersFor(PersistenceSession.java:1573)
at org.apache.isis.viewer.wicket.model.models.EntityCollectionModel$Type$1.loadInBulk(EntityCollectionModel.java:107)
at org.apache.isis.viewer.wicket.model.models.EntityCollectionModel$Type$1.load(EntityCollectionModel.java:93)
at org.apache.isis.viewer.wicket.model.models.EntityCollectionModel.load(EntityCollectionModel.java:454)
at org.apache.isis.viewer.wicket.model.models.EntityCollectionModel.load(EntityCollectionModel.java:70)
at org.apache.wicket.model.LoadableDetachableModel.getObject(LoadableDetachableModel.java:135)
at org.apache.isis.viewer.wicket.ui.components.collectioncontents.ajaxtable.CollectionContentsSortableDataProvider.size(CollectionContentsSortableDataProvider.java:68)
at org.apache.wicket.markup.repeater.data.DataViewBase.internalGetItemCount(DataViewBase.java:142)
at org.apache.wicket.markup.repeater.AbstractPageableView.getItemCount(AbstractPageableView.java:235)
at org.apache.wicket.markup.repeater.AbstractPageableView.getRowCount(AbstractPageableView.java:216)
at org.apache.wicket.markup.repeater.AbstractPageableView.getViewSize(AbstractPageableView.java:314)
at org.apache.wicket.markup.repeater.AbstractPageableView.getItemModels(AbstractPageableView.java:99)
at org.apache.wicket.markup.repeater.RefreshingView.onPopulate(RefreshingView.java:93)
at org.apache.wicket.markup.repeater.AbstractRepeater.onBeforeRender(AbstractRepeater.java:124)
at org.apache.wicket.markup.repeater.AbstractPageableView.onBeforeRender(AbstractPageableView.java:115)
at org.apache.wicket.Component.internalBeforeRender(Component.java:950)
at org.apache.wicket.Component.beforeRender(Component.java:1018)
at org.apache.wicket.MarkupContainer.onBeforeRenderChildren(MarkupContainer.java:1825)
... 81 more
Caused by: org.datanucleus.exceptions.NucleusException: Unable to create SQLExpression for mapping of type "org.datanucleus.store.rdbms.mapping.java.SerialisedMapping" since not supported
at org.datanucleus.store.rdbms.sql.expression.SQLExpressionFactory#newExpression(SQLExpressionFactory.java:189)
at org.datanucleus.store.rdbms.sql.expression.SQLExpressionFactory#newExpression(SQLExpressionFactory.java:155)
at org.datanucleus.store.rdbms.request.LocateBulkRequest#getStatement(LocateBulkRequest.java:158)
at org.datanucleus.store.rdbms.request.LocateBulkRequest#execute(LocateBulkRequest.java:283)
at org.datanucleus.store.rdbms.RDBMSPersistenceHandler#locateObjects(RDBMSPersistenceHandler.java:564)
at org.datanucleus.ExecutionContextImpl#findObjects(ExecutionContextImpl.java:3313)
at org.datanucleus.api.jdo.JDOPersistenceManager#getObjectsById(JDOPersistenceManager.java:1850)
at org.apache.isis.core.runtime.system.persistence.PersistenceSession#loadPersistentPojos(PersistenceSession.java:1010)
at org.apache.isis.core.runtime.system.persistence.PersistenceSession#adaptersFor(PersistenceSession.java:1603)
at org.apache.isis.core.runtime.system.persistence.PersistenceSession#adaptersFor(PersistenceSession.java:1573)
at org.apache.isis.viewer.wicket.model.models.EntityCollectionModel$Type$1#loadInBulk(EntityCollectionModel.java:107)
at org.apache.isis.viewer.wicket.model.models.EntityCollectionModel$Type$1#load(EntityCollectionModel.java:93)
at org.apache.isis.viewer.wicket.model.models.EntityCollectionModel#load(EntityCollectionModel.java:454)
at org.apache.isis.viewer.wicket.model.models.EntityCollectionModel#load(EntityCollectionModel.java:70)
at org.apache.wicket.model.LoadableDetachableModel#getObject(LoadableDetachableModel.java:135)
at org.apache.isis.viewer.wicket.ui.components.collectioncontents.ajaxtable.CollectionContentsSortableDataProvider#size(CollectionContentsSortableDataProvider.java:68)
at org.apache.wicket.markup.repeater.data.DataViewBase#internalGetItemCount(DataViewBase.java:142)
at org.apache.wicket.markup.repeater.AbstractPageableView#getItemCount(AbstractPageableView.java:235)
at org.apache.wicket.markup.repeater.AbstractPageableView#getRowCount(AbstractPageableView.java:216)
at org.apache.wicket.markup.repeater.AbstractPageableView#getViewSize(AbstractPageableView.java:314)
at org.apache.wicket.markup.repeater.AbstractPageableView#getItemModels(AbstractPageableView.java:99)
at org.apache.wicket.markup.repeater.RefreshingView#onPopulate(RefreshingView.java:93)
at org.apache.wicket.markup.repeater.AbstractRepeater#onBeforeRender(AbstractRepeater.java:124)
at org.apache.wicket.markup.repeater.AbstractPageableView#onBeforeRender(AbstractPageableView.java:115)
// <-- 8 times the following lines
at org.apache.wicket.Component#internalBeforeRender(Component.java:950)
at org.apache.wicket.Component#beforeRender(Component.java:1018)
at org.apache.wicket.MarkupContainer#onBeforeRenderChildren(MarkupContainer.java:1825)
at org.apache.wicket.Component#onBeforeRender(Component.java:3916)
// -->
at org.apache.wicket.Page#onBeforeRender(Page.java:801)
at org.apache.wicket.Component#internalBeforeRender(Component.java:950)
at org.apache.wicket.Component#beforeRender(Component.java:1018)
at org.apache.wicket.Component#internalPrepareForRender(Component.java:2236)
at org.apache.wicket.Page#internalPrepareForRender(Page.java:242)
at org.apache.wicket.Component#render(Component.java:2325)
at org.apache.wicket.Page#renderPage(Page.java:1018)
at org.apache.wicket.request.handler.render.WebPageRenderer#renderPage(WebPageRenderer.java:124)
at org.apache.wicket.request.handler.render.WebPageRenderer#respond(WebPageRenderer.java:195)
at org.apache.wicket.core.request.handler.RenderPageRequestHandler#respond(RenderPageRequestHandler.java:175)
at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor#respond(RequestCycle.java:895)
at org.apache.wicket.request.RequestHandlerStack#execute(RequestHandlerStack.java:64)
at org.apache.wicket.request.cycle.RequestCycle#execute(RequestCycle.java:265)
at org.apache.wicket.request.cycle.RequestCycle#processRequest(RequestCycle.java:222)
at org.apache.wicket.request.cycle.RequestCycle#processRequestAndDetach(RequestCycle.java:293)
at org.apache.wicket.protocol.http.WicketFilter#processRequestCycle(WicketFilter.java:261)
at org.apache.wicket.protocol.http.WicketFilter#processRequest(WicketFilter.java:203)
at org.apache.wicket.protocol.http.WicketFilter#doFilter(WicketFilter.java:284)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain#doFilter(ServletHandler.java:1668)
at org.apache.isis.core.webapp.diagnostics.IsisLogOnExceptionFilter#doFilter(IsisLogOnExceptionFilter.java:52)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain#doFilter(ServletHandler.java:1668)
at org.apache.shiro.web.servlet.AbstractShiroFilter#executeChain(AbstractShiroFilter.java:449)
at org.apache.shiro.web.servlet.AbstractShiroFilter$1#call(AbstractShiroFilter.java:365)
at org.apache.shiro.subject.support.SubjectCallable#doCall(SubjectCallable.java:90)
at org.apache.shiro.subject.support.SubjectCallable#call(SubjectCallable.java:83)
at org.apache.shiro.subject.support.DelegatingSubject#execute(DelegatingSubject.java:383)
at org.apache.shiro.web.servlet.AbstractShiroFilter#doFilterInternal(AbstractShiroFilter.java:362)
at org.apache.shiro.web.servlet.OncePerRequestFilter#doFilter(OncePerRequestFilter.java:125)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain#doFilter(ServletHandler.java:1668)
// ... some Jetty stuff
at java.lang.Thread#run(Thread.java:748)

经过一番研究，我认为问题 1和 2的问题似乎与此 ISIS 错误报告 #1902 有关。

简而言之：datanucleus 扩展插件解析机制似乎找不到 ISIS 值类型适配器，因此不知道如何序列化 ISIS 的 Blob/Clob 类型。

根据前面提到的ISIS错误报告，这个问题在1.17.0中得到了修复，所以我正在尝试从1.16.2升级到这个版本(这引入了许多其他问题，但这将是一个额外的主题)。

对于问题3，我找到了Minio，它基本上解决了我的问题，但它对于我的需求来说有点过大。我将继续寻找其他解决方案来将 Blob/Clobs 存储到本地文件系统，并牢记 Minio......

更新：

  1. 我将项目升级到 ISIS 版本 1.17.0。它解决了我在问题 1 中的问题(现在我得到了 Blob/Clob 对象的三列)。
  2. 问题 2 (NucleusException) 中的问题无法通过升级解决。我发现只有在返回带有 Blob/Clob 字段的域对象列表(即如果呈现为独立表)时才会抛出它。如果我直接进入对象的实体视图，则不会引发异常，并且我可以看到/修改/下载 Blob/Clob 内容。
  3. 与此同时，我编写了自己的datanucleus插件，它将Blob/Clobs作为文件存储在文件系统上。

更新 2

  1. 我找到了规避org.datanucleus.exceptions.NucleusException: Unable to create SQLExpression for mapping of type "org.apache.isis.objectstore.jdo.datanucleus.valuetypes.IsisClobMapping" since not supported的解决方案。这似乎是批量加载的问题(但我不知道任何细节)。 通过属性isis.persistor.datanucleus.standaloneCollection.bulkLoad=false停用批量加载(最初设置为由 ISIS 原型true)解决了这个问题。

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