Try ... Catch DuplicateKeyException

Question

I have seen posts on using 'DuplicateKeyException' for Try ... Catch in C#. However, it does not seem to work for VB. Is it not supported in VB?

Answer 1

Hi Lee,

It does support in VB. You can refer to this MSDN document,
http://msdn.microsoft.com/en-us/library/system.data.linq.duplicatekeyexception.aspx

If you want to use it, first add reference to System.Data.Linq dll to your project. Then "Imports System.Data.Linq"

Could you please give the detail code that you are using ?


Best Regards
Yichun Feng

---

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Answer 2

Yichen,

System.Data.Linq was/is listed as a Reference.
The following are extracts of the Try ...Catch that does not catch Duplicate Key Exceptions

*****

Imports

 

System

Imports

 

System.Collections

Imports

 

System.Collections.Generic

Imports

 

System.Data.Linq

Imports

 

System.Linq

Imports

 

sqlLineImportNS.linqDataClassesDataContext

*****

 

Try

sqlGPdc.PersonImportAutoIds.InsertOnSubmit(piar)

sqlGPdc.SubmitChanges(ConflictMode.ContinueOnConflict)

 

Catch ex As ChangeConflictException

DisplayConcurrencyCatch(

"AppendPersonImportAutoId", ex, eDisplayField.ePerson)

 

Catch ex As DuplicateKeyException

DisplayDuplicateKeyCatch(

"AppendPersonImportAutoId", ex, eDisplayField.ePerson)

 

Catch ex As Exception

DisplayLog(eDisplay.eCatch,

"AppendPersonImportAutoId: " & ex.Message)

 

End Try

*****

 

I have narrowed the problem to occur when a 'Drop & Create' and 'Reseed' to 0 is executed by another application.
The problem still exists when I add the 'Drop & Create' and 'Reseed' code to this application.

ChangeConflictException did not require any additional definitions and did catch conflicts. DuplicateKeyException selection was available by IntelleSence for selection. Does it require the object class to be added to the project?

Thanks in advance for your continued support.
Lee_37122

Answer 3

Hi Lee,

 

DuplicateKeyException is thrown when an attempt is made to add an object to the identity cache by using a key that is already being used.

 

That means, it is thrown when you insert two records with the same PK into the context. For example,

 

        Try

            Dim context As New DataClasses1DataContext

            Dim s As New Stu

            s.id = 1

 

            context.Stus.InsertOnSubmit(s)

 

            Dim s1 As New Stu

            s1.id = 1

 

            context.Stus.InsertOnSubmit(s1)

 

            context.SubmitChanges()

        Catch ex As DuplicateKeyException

            Console.WriteLine(ex.ToString)

        End Try

 

If the record you want to insert has the same PK in DB, the exception is SqlException. You can try it in C#,

 

            try

            {

 

                DataClasses1DataContext context = new DataClasses1DataContext();

 

                Stu s = new Stu();

                s.id = 1;

 

                context.Stus.InsertOnSubmit(s);

 

 

                context.SubmitChanges();

            }

            catch (DuplicateKeyException ex)

            {

                Console.WriteLine(ex.ToString());

            }

            catch (SqlException ex)

            {

                Console.WriteLine(ex.ToString());

            }

 

So, the problem is not due to the language differences, but the Exception type.

 

 

Does this work for you? If you have any questions or concerns, please update the thread and we will have a further discussion.

 

 

Best Regards

Yichun Feng

---

Please remember to mark the replies as answers if they help and unmark them if they provide no help.
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