原文：http://apobekiaris.blogspot.com/2011/01/easy-sequential-numbers.html
Easy Sequential numbers(易用的序列号)
Where they can be used?? In many places for example invoices, sales orders etc.
他们能用在哪里？例如，在许多地方，发票，销售订单等等。
One could tell that this is an easy task and maybe that assumption is right but let me write down some real world requirements that can prove the opposite to you.
有人告诉你这个任务很简单，也许那是正确的，但，让我们写一个些真正的需求，来证明那是错误的。
- Invoices Number Uniqueness should be quarantine in a multi user environment
在一个多用户环境，独一无二的发票号应当是隔离的。 - Number number should be sequential
数字号应当是连续的。 - Invoices numbers may have series (eg AB-1001 for invoices coming from store sales , EP-1001 for invoices coming from patient treatment)
发票号，可能是个系列号(例如AB-1001 来自店面销售发票，EP-1001 来自住院发票) - Starting number must be configurable. (eg need to start numbering at 5000 this year, and next year start at 7000)
开始号必须能配置(例如，今年需要从5000开始，下一年从7000开始) - There should be a way to reuse numbers of deleted invoices
应当有一种方法可以重用删除的发票号。 - Storage (table schema) of invoice numbers should be controlled by the user
发票号的存储(表配置)应当由用户控制。 - End user API should be very flexible and easy
终端用户应用程序接口应当非常灵活和易用。 - Of course whatever you build has to be available in both win and web platforms
当然，无论如何，你必须建立能在win和web两种平台上可用。
Now what you think? How much time do you need to build that?
现在，你在思考什么？你需要多少时间才能建立那些功能？
If you have some XAF experience it will be about only some hrs work to create a reusable code that fellow devs and future projects can utilize. So in this post i am going to go through the process step by step
如果你有一些的XAF开发经验，这就需要几个小时就可以建立一个可重用的代码，供开发者和将来的工程使用。因此，在本篇，我将循序渐进的说明如何实现这些。
Step1: Check Devexpress support center
第一步：查看Devexpress支持中心
SC has samples for thousand of cases so before building anything it is most advisable to check there.
支持中心有成千的案例，因此，在构建任何程序之前，最好去那里查看。
Searching revealed this one (这是一个搜索结果)
How to generate and assign a sequential number for a business object within a database transaction, while being a part of a successful saving process (XAF)
在一个数据库事务中如何给业务对象生成和标识一个序列号，当成功存储时(XAF)。
That sample is using ExcplicitUnitOfWork (in other words explicit sql transaction) and that can guarantee requirement 1,2
那个例子用了ExcplicitUnitOfWork(换句话说，明确的sql事务),那能保证实现需求1，2。
Step2: Refactor the sample to fit your needs
第二步：重构例子适应你的需求
Although the sample can be used as is in real world, has some requirements that are making it less flexible. It requires to inherit from a special BasePersistentObject class.
虽然例子可以在现实中用，但有一些需求，构建它是不太灵活。它需要继承一个指定类BasePersistentObject。
To overcome that we can introduce an interface instead and push all depended code to our SequenceGenerator class
要克服那些问题，我们引入一个接口替代，将所有依赖代码放入我们的SequenceGenerator类。
public interface ISupportSequenceObject {
long Sequence { get; set; }
}
Now we can inherit from any object as you see in the above code and we only have to write the code that is inside the OnSaving method! .
现在，你在上面代码看到，我们可以从任何对象继承，我们只需在OnSaving方法写代码。
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The best part is that we do not even spent one minute to think about the validity of the generating seq numbers code. That is Devexpress job and they are best in doing it. What we could do is just track the issue for changes (maybe bugs will raise from other users in future ) I am happy with this refactoring so lets move on to the other requirements. |
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Time spent 1.5hrs (花费1.5小时)
Invoices numbers may have series(可能有系列的发票号)
How about it?? Should be very easy if we understand what are SequenceGenerator does. It saves a number for a specific type in the database. So instead of a specific type we can refactor it to save a specific type and a series string. We can do that by introducing a new Prefix property to our ISupportSequenceObject interface and refactor our SequenceGenerator to save that prefix as well .
怎么样？如果我们理解了SequenceGenerator能做什么，应当很容易。它保存一个特定类型的号码在数据库中。因此不是一个特定类型，我们重构它，保存一个特定类型和一个系列字符串。我们通过ISupportSequenceObject接口引入一个新的前缀属性，重构我的SequenceGenerator同样保存那个前缀
public interface ISupportSequenceObject {
long Sequence { get; set; }
string Prefix { get; }
}
our previous front end API was left as simple as it was b4 as you see bellow
Starting number must be configurable. (eg need to start numbering at 5000 this year, and next year start at 7000)
必须能配置开始号码。(例如，今年需要从5000开始，明年从7000开始)
Ok that sounds very similar to our previous req. In essence the year is just a serie, so we could just change our class to
好的，听起来跟以前的需求很相似。本质上今年只是一个系列，因此，我们仅更改我们的类。
string ISupportSequenceObject.Prefix {
get { return Serie.ToString()+DateTime.Today.Year; }
}
and now our numbers are unique per serier+year!. And how can we control the starting number?
Very easy as everything in XAF!. Sequence numbers are saved using a persistent object, so the thing we need to do is just create a new Sequence number manual and the other numbers will follow since they are sequential.
现在，我们的数字，每个系列+年是唯一的。如何控制开始数字？在XAF中是非常容易的。序列号是用持久对象保存，因此这需要手动创建一个新的序列号，其他数字将由序列号生成。
var unitOfWork = new UnitOfWork();
var sequenceObjects = Enum.GetValues(typeof (SerieEnum)).Cast<SerieEnum>().Select(
serie => SequenceGenerator.CreateSequenceObject(serie.ToString() + 2012, unitOfWork));
foreach (var sequenceObject in sequenceObjects) {
sequenceObject.NextSequence = 7000;
}
unitOfWork.CommitChanges();
Time spent 30min (用时30分钟)
There should be a way to reuse numbers of deleted invoices
应当有方法重用删除的发票号
What does that mean? When an object that supports sequences (ISupportSequence object) is deleted we need to store the deleted sequence number and allow end user through UI to reuse it at a later time.
什么意思？当删除一个到序列号的对象，我们需要存储删除的序列号，允许终端用户稍后通过界面重用它。
We already have an SequenceObject that stores the sequence number what we miss is an one to many relation with an object that stores deleted numbers. The following class will do the job
我们已经有一个SwquenceObject,存储一个一对多对象的已删除的序列号。下面类将处理这项工作。
public class SequenceReleasedObject : XpandBaseCustomObject {
public SequenceReleasedObject(Session session)<