Hur du identifierar och löser motstridiga inskick

LINQ till SQL innehåller många resurser för att identifiera och lösa konflikter som härrör från ändringar i databasen med flera användare. Mer information finns i Så här hanterar du ändringskonflikter.

Exempel

I följande exempel visas ett try/catch block som fångar upp ett ChangeConflictException undantag. Information om entitet och medlem för varje konflikt visas i konsolfönstret.

// 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($"Table name: {metatable.TableName}");
        Console.Write("Customer ID: ");
        Console.WriteLine(entityInConflict.CustomerID);
        foreach (MemberChangeConflict mcc in occ.MemberConflicts)
        {
            object currVal = mcc.CurrentValue;
            object origVal = mcc.OriginalValue;
            object databaseVal = mcc.DatabaseValue;
            MemberInfo mi = mcc.Member;
            Console.WriteLine($"Member: {mi.Name}");
            Console.WriteLine($"current value: {currVal}");
            Console.WriteLine($"original value: {origVal}");
            Console.WriteLine($"database value: {databaseVal}");
        }
    }
}
catch (Exception ee)
{
    // Catch other exceptions.
    Console.WriteLine(ee.Message);
}
finally
{
    Console.WriteLine("TryCatch block has finished.");
}

' 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

Se även

• Att göra och skicka dataändringar
• Så här hanterar du ändringskonflikter