Orders, articles or other business entities often require that you have user-friendly Id or Code fields that end-users can memorize and use during phone conversations. They are usually sequential, but some gaps can be allowed as well (e.g., when an order is deleted). Refer to this StackOverFlow thread for more information on this common scenario, and a possible implementation.
Take special note that you can use any strings as the "seqType" and "serverPrefix" (optional) parameters that allow you to run named sequences in parallel (these parameters determine criteria for updating right sequences). In the demo, I am just using the full persistent type name and a custom prefix, which can be changed as you need:
Question Comments
Added By:
Gareth- at:
10/2/2013 5:58:17 AM Thanks, works perfectly - I've seeded the ID by manually changing the [Oid] in the IDGeneratorTable, do I need to worry about the [OptimisicLockField] or will this update automatically?
Added By:
Dennis (DevExpress Support) at:
10/2/2013 7:10:50 AM @Gareth: No, you do not need to care about the OptimisticLockField.
Added By:
MohammedFarooq at:
12/2/2013 1:07:31 AM Hi,
The code is really helpful but it increments the value of code even if the record is deleted! How can we stop the code to increase its value when a record is deleted?
Added By:
MohammedFarooq at:
12/2/2013 1:25:16 AM I manage to figure out the solution. I have just added the IsDeleted checking and it worked like a charm!!!
Protected Overrides Sub OnSaving()
If (Not IsDeleted) Then
Me.codeCore = String.Format("N{0:D6}", DistributedIdGeneratorHelper.Generate(Me.Session.DataLayer, Me.GetType().FullName, String.Empty))
End If
MyBase.OnSaving()
End Sub
Added By:
Dennis (DevExpress Support) at:
12/2/2013 1:26:50 AM @Mohammed: Yes, your solution is correct. I will consider updating this example accordingly. Thanks for your input in this regard.
Added By:
rushdan . at:
11/6/2014 12:02:48 AM Hallo
I do not understand about explanation. What I know is, after I run the application, then save the data , it will execute Code number automatically.
Is it this example to show how to execute auto increase number ? Thanks
Added By:
Dennis (DevExpress Support) at:
11/6/2014 2:00:43 AM @Rushdan: With the current implementation, the generation code is executed when the persistent object is being saved (OnSaving). I do not quite understand your last question. The functionality implemented in this example is well-detailed in the description and it can also be seen from simple code.
Added By:
Andrew Bingham 2 at:
2/5/2015 12:40:25 AM "override its AfterConstruction method, as shown in the Solution2.Module\BusinessObjects\DomainObject1.xx file"
1. I cannot find the DomainObject1 file in the sample
2. The only BusinessObject is Order.cs which does not have an AfterConstruction method
3. What code need to go in AfterConstruction method?
4. What are the advantages / disadvantages compared to E2829?
Added By:
Dennis (DevExpress Support) at:
2/5/2015 12:47:04 AM @Andrew: Thanks for your feedback.
1-3. I've corrected this misprint in the description.
3. This particular solution is simpler to implement than E2829.Added By:
Vishwas Mokashi at:
4/21/2015 8:52:32 AM Is there any provision so that we can restart the Sequence Number after say an Year is completed?. Also, any way to give the start number for the sequence?.
Added By:
Dennis (DevExpress Support) at:
4/21/2015 8:57:35 AM @Vishwas: Sure, you can do this. Technically, the information about the last sequence number is stored in the Oid column of the IDGeneratorTable table with the help of the OidGenerator persistent class. You can modify this data using either ADO.NET or XPO means.
Added By:
Vishwas Mokashi at:
4/21/2015 9:02:11 AM Ok thanks Dennis...will try
Added By:
MohammedFarooq at:
10/14/2015 2:37:53 AM Dear Dennis,
I have applied this logic in my project which also has validation enabled. Now the issue is, if the validation of the document fails while saving the new number is generated. And when the user saves the document again then a new number is generated as well.
Added By:
Dennis (DevExpress Support) at:
10/14/2015 2:58:59 AM @Mohammed: The original example has the if(string.IsNullOrEmpty(Code)) check that prevents multiple generations. Have you applied this code in your project? If this does not help, submit a separate ticket and attach your problematic sample so we can assist you further.Added By:
MohammedFarooq at:
10/14/2015 5:03:57 AM You hit a bull's eye! I didn't have the if(string.IsNullOrEmpty(Code)) in my code.
Was it added recently? Because i followed this example before and somehow i missed it.
Added By:
Dennis (DevExpress Support) at:
10/14/2015 5:18:38 AM You're always welcome. AFAIK, I added it a year ago or so.Added By:
Paul Kubb at:
3/16/2016 2:14:58 AM Would you please describe more in detail about serverprefix table? how and when to use it?
I cannot find any documentation about it also.Added By:
Dennis (DevExpress Support) at:
3/17/2016 1:57:56 AM @Paul: It was a mistake in the original description, because this table is actually unused by the DistributedIdGeneratorHelper class. Please accept my apologies for the confusion. As for the "string serverPrefix" parameter of the Generate method, it allows you to run several sequences in parallel. Refer to the "C:\Program Files (x86)\DevExpress 1X.X\Components\Sources\DevExpress.Persistent\DevExpress.Persistent.BaseImpl\IDGenerator.cs" source file for more details.
Added By:
Paul Kubb at:
8/4/2016 9:44:09 AM I have read a source file and have several questions aboud DistributedIdGeneratorHelper.Generate():
1. it seems like you intend to create a separate new session, attempt to save it to the database separately until success and return its Oid. Why can't we use the bo's existing session here?
2. by this design, do you intend to avoid some multi-user problem or something? if so, please explain why having a separate session will overcome it
3. if the OidGenerator is saved successfully in a separate session but the main bo's save event is dead, will the OidGenerator's save event be rolled back? or will we have a jumpy running number instead?
thanks in advance
Added By:
Dennis (DevExpress Support) at:
8/5/2016 7:12:09 AM @Paul:
A1-2: Your understanding of class design is correct. A separate session will help to avoid concurrency issues in a multi-user environment: if another user generated a new number while you were saving your own, the locking exception occurs and a new attempt to generate the next number for you starts in the loop.
A3:No, it will not. See my answer in the T304004 ticket for more details.
Added By:
wang yu 4 at:
9/23/2016 12:59:54 AM does it support middle tier ?Added By:
Dennis (DevExpress Support) at:
9/23/2016 2:13:47 AM @Wang: As in the example's description, the DistributedIdGeneratorHelper class currently does not support the middle-tier Application Server scenario, because the Session.DataLayer property is not initialized in this case.
Added By:
13 chi at:
10/3/2016 2:21:46 AM That fix for middle-tier doesn't work well.
[C#]
newSession(sourceSession.ObjectLayer).DataLayer;
still returns null.
Added By:
Dennis (DevExpress Support) at:
10/4/2016 2:41:06 AM @13 chi: Thanks for your report and please accept my apologies for the inconvenience here. I will update the article with a better solution as soon as it is available.Added By:
Dennis (DevExpress Support) at:
10/4/2016 10:29:13 AM @13 chi: I've updated the E4904 example classes for the
middle-tier Application Server scenario (see additional checks in the OnSaving method). Note that in this scenario, the generated sequence number will appear in the WinForms DetailView only after a manual refresh (i.e., it will be empty right away after saving a record), because the sequence is generated on the server side only and is not passed to the client.