如何从EclipseLink的ClassDescriptor中获取待删除记录的ID值？

现有运行的软删除定制器代码 #

public class SoftDeleteCustomizer implements DescriptorCustomizer {

  @Override
  public void customize(ClassDescriptor descriptor) {
    descriptor.getQueryManager().setDeleteSQLString(
        String.format("UPDATE %s SET record_status = 'D', record_status_time = CURRENT_TIMESTAMP WHERE id = #ID",
                      descriptor.getTableName()
        )
    );
  }

}

需求与问题 #

需要在软删除操作中添加记录删除者的信息，倾向于用参数方式传递，但使用DeleteObjectQuery时，不知道如何获取待删除记录的ID/主键值来设置参数。当前尝试的代码如下：

@Override
public void customize(final ClassDescriptor descriptor) {
  final DeleteObjectQuery query = new DeleteObjectQuery();
  query.addArgument("DELETED_BY", String.class);
  query.addArgument("ID", Long.class);
  query.addArgumentValue(SecurityUtils.getUsername());
  query.addArgumentValue(...); // 不知道如何获取待删除记录的ID
  query.setSQLString(String.format(DELETE_SQL, descriptor.getTableName()));
  descriptor.getQueryManager().setDeleteQuery(query);
}

解决方案 #

不需要手动添加ID参数并赋值，EclipseLink的DeleteObjectQuery会自动处理主键参数绑定。可以通过查询事件动态注入删除者信息，同时利用框架特性自动绑定主键值，具体实现如下：

方式一：适配任意主键（单/复合主键） #

public class SoftDeleteCustomizer implements DescriptorCustomizer {
    private static final String DELETE_SQL_TEMPLATE = "UPDATE %s SET record_status = 'D', record_status_time = CURRENT_TIMESTAMP, deleted_by = ? WHERE %s";

    @Override
    public void customize(final ClassDescriptor descriptor) {
        // 动态构建主键WHERE子句，适配单/复合主键
        List<DatabaseField> primaryKeyFields = descriptor.getPrimaryKeyFields();
        StringBuilder whereClause = new StringBuilder();
        for (int i = 0; i < primaryKeyFields.size(); i++) {
            DatabaseField field = primaryKeyFields.get(i);
            if (i > 0) {
                whereClause.append(" AND ");
            }
            whereClause.append(field.getName()).append(" = #").append(field.getName());
        }

        // 构建完整软删除SQL
        String deleteSql = String.format(DELETE_SQL_TEMPLATE, descriptor.getTableName(), whereClause.toString());

        // 配置DeleteObjectQuery
        DeleteObjectQuery deleteQuery = new DeleteObjectQuery();
        deleteQuery.setSQLString(deleteSql);

        // 添加查询监听器，在执行前注入删除者信息
        deleteQuery.addQueryListener(new QueryAdapter() {
            @Override
            public void prepareQuery(DatabaseQuery query, Record record, Session session) {
                DatabaseCall call = query.getDatabaseCall();
                // 注入当前登录用户名到参数中
                call.addArgumentValue(SecurityUtils.getUsername());
            }
        });

        descriptor.getQueryManager().setDeleteQuery(deleteQuery);
    }
}

方式二：已知主键字段名（简化版） #

如果确定实体主键字段名为id，可以直接写死占位符，代码更简洁：

public class SoftDeleteCustomizer implements DescriptorCustomizer {
    private static final String DELETE_SQL_TEMPLATE = "UPDATE %s SET record_status = 'D', record_status_time = CURRENT_TIMESTAMP, deleted_by = ? WHERE id = #id";

    @Override
    public void customize(final ClassDescriptor descriptor) {
        String deleteSql = String.format(DELETE_SQL_TEMPLATE, descriptor.getTableName());

        DeleteObjectQuery deleteQuery = new DeleteObjectQuery();
        deleteQuery.setSQLString(deleteSql);

        deleteQuery.addQueryListener(new QueryAdapter() {
            @Override
            public void prepareQuery(DatabaseQuery query, Record record, Session session) {
                DatabaseCall call = query.getDatabaseCall();
                call.addArgumentValue(SecurityUtils.getUsername());
            }
        });

        descriptor.getQueryManager().setDeleteQuery(deleteQuery);
    }
}

关键说明 #

• #字段名是EclipseLink的参数占位符，框架会自动从待删除实体中对应字段取值并绑定，无需手动设置ID参数。
• 使用QueryListener的prepareQuery方法注入删除者信息，该方法在查询执行前触发，能获取到当前上下文的用户名，避免在定制器初始化时无法获取动态数据的问题。

内容的提问来源于stack exchange，提问作者Jasper de Vries