我需要对存储在面向文档的数据库 (MongoDB) 中的(简单)Java 对象图进行版本控制.对于关系数据库和 Hibernate,我发现了 Envers 并对这些可能性感到非常惊讶.是否有类似的东西可以与 Spring Data Documents 一起使用?
I need to do versioning on (simple) Java object graphs stored in a document-oriented database (MongoDB). For relational databases and Hibernate, I discovered Envers and am very amazed about the possibilities. Is there something similar that can be used with Spring Data Documents?
我发现 这篇文章概述了我的想法(以及更多...)关于存储对象版本,我当前的实现工作类似,因为它将对象的副本存储在带有时间戳的单独历史集合中,但我想改进它以节省存储空间.因此,我认为我需要在对象树上实现差异"操作和重构旧对象的合并"操作.有没有图书馆可以帮助解决这个问题?
I found this post outlining the thoughts I had (and more...) about storing the object versions, and my current implementation works similar in that it stores copies of the objects in a separate history collection with a timestamp, but I would like to improve this to save storage space. Therefore, I think I need to implement both a "diff" operation on object trees and a "merge" operation for reconstructing old objects. Are there any libraries out there helping with this?
编辑:任何使用 MongoDB 和版本控制的经验都非常感谢!我认为很可能不会有 Spring Data 解决方案.
Edit: Any experiences with MongoDB and versioning highly appreciated! I see most probably there won't be a Spring Data solution.
我们正在使用一个基础实体(我们在其中设置 Id、创建 + 上次更改日期......).在此基础上,我们使用了一个通用的持久化方法,看起来像这样:
We're using a base entity (where we set the Id, creation + last change dates,...). Building upon this we're using a generic persistence method, which looks something like this:
@Override
public <E extends BaseEntity> ObjectId persist(E entity) {
delta(entity);
mongoDataStore.save(entity);
return entity.getId();
}
delta 方法看起来像这样(我会尽量使它尽可能通用):
The delta method looks like this (I'll try to make this as generic as possible):
protected <E extends BaseEntity> void delta(E newEntity) {
// If the entity is null or has no ID, it hasn't been persisted before,
// so there's no delta to calculate
if ((newEntity == null) || (newEntity.getId() == null)) {
return;
}
// Get the original entity
@SuppressWarnings("unchecked")
E oldEntity = (E) mongoDataStore.get(newEntity.getClass(), newEntity.getId());
// Ensure that the old entity isn't null
if (oldEntity == null) {
LOG.error("Tried to compare and persist null objects - this is not allowed");
return;
}
// Get the current user and ensure it is not null
String email = ...;
// Calculate the difference
// We need to fetch the fields from the parent entity as well as they
// are not automatically fetched
Field[] fields = ArrayUtils.addAll(newEntity.getClass().getDeclaredFields(),
BaseEntity.class.getDeclaredFields());
Object oldField = null;
Object newField = null;
StringBuilder delta = new StringBuilder();
for (Field field : fields) {
field.setAccessible(true); // We need to access private fields
try {
oldField = field.get(oldEntity);
newField = field.get(newEntity);
} catch (IllegalArgumentException e) {
LOG.error("Bad argument given");
e.printStackTrace();
} catch (IllegalAccessException e) {
LOG.error("Could not access the argument");
e.printStackTrace();
}
if ((oldField != newField)
&& (((oldField != null) && !oldField.equals(newField)) || ((newField != null) && !newField
.equals(oldField)))) {
delta.append(field.getName()).append(": [").append(oldField).append("] -> [")
.append(newField).append("] ");
}
}
// Persist the difference
if (delta.length() == 0) {
LOG.warn("The delta is empty - this should not happen");
} else {
DeltaEntity deltaEntity = new DeltaEntity(oldEntity.getClass().toString(),
oldEntity.getId(), oldEntity.getUuid(), email, delta.toString());
mongoDataStore.save(deltaEntity);
}
return;
}
我们的 delta 实体看起来像这样(没有 getter + setter、toString、hashCode 和 equals):
Our delta entity looks like that (without the getters + setters, toString, hashCode, and equals):
@Entity(value = "delta", noClassnameStored = true)
public final class DeltaEntity extends BaseEntity {
private static final long serialVersionUID = -2770175650780701908L;
private String entityClass; // Do not call this className as Morphia will
// try to work some magic on this automatically
private ObjectId entityId;
private String entityUuid;
private String userEmail;
private String delta;
public DeltaEntity() {
super();
}
public DeltaEntity(final String entityClass, final ObjectId entityId, final String entityUuid,
final String userEmail, final String delta) {
this();
this.entityClass = entityClass;
this.entityId = entityId;
this.entityUuid = entityUuid;
this.userEmail = userEmail;
this.delta = delta;
}
希望这可以帮助您入门:-)
Hope this helps you getting started :-)
这篇关于Java MongoDB 对象版本控制的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持跟版网!