How to: Detect and Resolve Conflicting Submissions (LINQ to SQL)
LINQ to SQL provides many resources for detecting and resolving conflicts that stem from multi-user changes to the database. For more information, see How to: Manage Change Conflicts (LINQ to SQL).
Example
The following example shows a try/catch block that catches a ChangeConflictException exception. Entity and member information for each conflict is displayed in the console window.
Note
You must include the using System.Reflection directive (Imports System.Reflection in Visual Basic) to support the information retrieval. For more information, see System.Reflection.
' Imports System.Reflection
Dim newCust As New Customer()
newCust.City = "Auburn"
newCust.CustomerID = "AUBUR"
newCust.CompanyName = "AubCo"
db.Customers.InsertOnSubmit(newCust)
Try
db.SubmitChanges(ConflictMode.ContinueOnConflict)
Catch e As ChangeConflictException
Console.WriteLine("Optimistic concurrency error.")
Console.WriteLine(e.Message)
Console.ReadLine()
For Each occ In db.ChangeConflicts
Dim metatable As MetaTable = db.Mapping.GetTable(occ.Object.GetType())
Dim entityInConflict = CType(occ.Object, Customer)
Console.WriteLine("Table name: {0}", metatable.TableName)
Console.Write("Customer ID: ")
Console.WriteLine(entityInConflict.CustomerID)
For Each mcc In occ.MemberConflicts
Dim currVal = mcc.CurrentValue
Dim origVal = mcc.OriginalValue
Dim databaseVal = mcc.DatabaseValue
Dim mi = mcc.Member
Console.WriteLine("Member: {0}", mi.Name)
Console.WriteLine("current value: {0}", currVal)
Console.WriteLine("original value: {0}", origVal)
Console.WriteLine("database value: {0}", databaseVal)
Next
Next
Catch ee As Exception
' Catch other exceptions.
Console.WriteLine(ee.Message)
Finally
Console.WriteLine("TryCatch block has finished.")
End Try
// using System.Reflection;
Northwnd db = new Northwnd(@"c:\northwnd.mdf");
Customer newCust = new Customer();
newCust.City = "Auburn";
newCust.CustomerID = "AUBUR";
newCust.CompanyName = "AubCo";
db.Customers.InsertOnSubmit(newCust);
try
{
db.SubmitChanges(ConflictMode.ContinueOnConflict);
}
catch (ChangeConflictException e)
{
Console.WriteLine("Optimistic concurrency error.");
Console.WriteLine(e.Message);
Console.ReadLine();
foreach (ObjectChangeConflict occ in db.ChangeConflicts)
{
MetaTable metatable = db.Mapping.GetTable(occ.Object.GetType());
Customer entityInConflict = (Customer)occ.Object;
Console.WriteLine("Table name: {0}", metatable.TableName);
Console.Write("Customer ID: ");
Console.WriteLine(entityInConflict.CustomerID);
foreach (MemberChangeConflict mcc in occ.MemberConflicts)
{
object currVal = mcc.CurrentValue;
object origVal = mcc.OriginalValue;
object databaseVal = mcc.DatabaseValue;
MemberInfo mi = mcc.Member;
Console.WriteLine("Member: {0}", mi.Name);
Console.WriteLine("current value: {0}", currVal);
Console.WriteLine("original value: {0}", origVal);
Console.WriteLine("database value: {0}", databaseVal);
}
}
}
catch (Exception ee)
{
// Catch other exceptions.
Console.WriteLine(ee.Message);
}
finally
{
Console.WriteLine("TryCatch block has finished.");
}