DbContext élimine les modifications sans élimination

public void RejectChanges()
    {
        foreach (var entry in ChangeTracker.Entries())
        {
            switch (entry.State)
            {
                case EntityState.Modified:
                case EntityState.Deleted:
                    entry.State = EntityState.Modified; //Revert changes made to deleted entity.
                    entry.State = EntityState.Unchanged;
                    break;
                case EntityState.Added:
                    entry.State = EntityState.Detached;
                    break;
            }
        }
    }

Dans le cas simple d'annuler les modifications apportées aux propriétés d'une entité unique, vous pouvez définir les valeurs actuelles pour les valeurs d'origine.

context.Entry(myEntity).CurrentValues.SetValues(context.Entry(myEntity).OriginalValues);
//you may also need to set back to unmodified -
//I'm unsure if EF will do this automatically
context.Entry(myEntity).State = EntityState.UnModified;

ou sinon recharger (mais les résultats en db hit)

context.Entry(myEntity).Reload();

Vous colud essayer de le faire manuellement, quelque chose comme ça.. pas sûr que cela fonctionne pour votre scénario, mais vous pouvez lui donner un essai:

public void UndoAll(DbContext context)
    {
        //detect all changes (probably not required if AutoDetectChanges is set to true)
        context.ChangeTracker.DetectChanges();

        //get all entries that are changed
        var entries = context.ChangeTracker.Entries().Where(e => e.State != EntityState.Unchanged).ToList();

        //somehow try to discard changes on every entry
        foreach (var dbEntityEntry in entries)
        {
            var entity = dbEntityEntry.Entity;

            if (entity == null) continue;

            if (dbEntityEntry.State == EntityState.Added)
            {
                //if entity is in Added state, remove it. (there will be problems with Set methods if entity is of proxy type, in that case you need entity base type
                var set = context.Set(entity.GeType());
                set.Remove(entity);
            }
            else if (dbEntityEntry.State == EntityState.Modified)
            {
                //entity is modified... you can set it to Unchanged or Reload it form Db??
                dbEntityEntry.Reload();
            }
            else if (dbEntityEntry.State == EntityState.Deleted)
                //entity is deleted... not sure what would be the right thing to do with it... set it to Modifed or Unchanged
                dbEntityEntry.State = EntityState.Modified;                
        }
    }

Vous pouvez appliquer ceci:

context.Entry(TEntity).Reload();

je l'ai essayer et sa fonctionne bien pour moi.

Remarque: Cette méthode ( recharger) Recharge l'entité de la base de données en remplaçant toute valeur de propriété par des valeurs de la base de données. L'entité sera dans l'état Inchangé après l'appel de cette méthode.

ceci est basé sur la réponse de Surgey Shuvalov. Il ajoute la prise en charge des changements de propriétés de navigation.

public void RejectChanges()
{
    RejectScalarChanges();
    RejectNavigationChanges();
}

private void RejectScalarChanges()
{
    foreach (var entry in ChangeTracker.Entries())
    {
        switch (entry.State)
        {
            case EntityState.Modified:
            case EntityState.Deleted:
                entry.State = EntityState.Modified; //Revert changes made to deleted entity.
                entry.State = EntityState.Unchanged;
                break;
            case EntityState.Added:
                entry.State = EntityState.Detached;
                break;
        }
    }
}

private void RejectNavigationChanges()
{
    var objectContext = ((IObjectContextAdapter)this).ObjectContext;
    var deletedRelationships = objectContext.ObjectStateManager.GetObjectStateEntries(EntityState.Deleted).Where(e => e.IsRelationship && !this.RelationshipContainsKeyEntry(e));
    var addedRelationships = objectContext.ObjectStateManager.GetObjectStateEntries(EntityState.Added).Where(e => e.IsRelationship);

    foreach (var relationship in addedRelationships)
        relationship.Delete();

    foreach (var relationship in deletedRelationships)
        relationship.ChangeState(EntityState.Unchanged);
}

private bool RelationshipContainsKeyEntry(System.Data.Entity.Core.Objects.ObjectStateEntry stateEntry)
{
    //prevent exception: "Cannot change state of a relationship if one of the ends of the relationship is a KeyEntry"
    //I haven't been able to find the conditions under which this happens, but it sometimes does.
    var objectContext = ((IObjectContextAdapter)this).ObjectContext;
    var keys = new[] { stateEntry.OriginalValues[0], stateEntry.OriginalValues[1] };
    return keys.Any(key => objectContext.ObjectStateManager.GetObjectStateEntry(key).Entity == null);
}

je suis tombé sur une mauvaise surprise - appel à ChangeTracker.Entrées() se bloque si vous avez besoin de faire reculer des modifications dues à une exception dans DbContext par exemple

System.InvalidOperationException: 
'The property 'Id' on entity type 'TestEntity' is part of a key and so cannot be modified or marked as modified. 
To change the principal of an existing entity with an identifying foreign key first delete the dependent and invoke 'SaveChanges' then associate the dependent with the new principal.'

j'ai donc créé une version hackée du rollback manuel

    public async Task RollbackChanges()
    {
        var oldBehavoir = ChangeTracker.QueryTrackingBehavior;
        var oldAutoDetect = ChangeTracker.AutoDetectChangesEnabled;

        // this is the key - disable change tracking logic so EF does not check that there were exception in on of tracked entities
        ChangeTracker.QueryTrackingBehavior = QueryTrackingBehavior.NoTracking;
        ChangeTracker.AutoDetectChangesEnabled = false;

        var entries = ChangeTracker.Entries().ToList();

        foreach (var entry in entries)
        {
            switch (entry.State)
            {
                case EntityState.Modified:
                    await entry.ReloadAsync();
                    break;
                case EntityState.Deleted:
                    entry.State = EntityState.Modified; //Revert changes made to deleted entity.
                    entry.State = EntityState.Unchanged;
                    break;
                case EntityState.Added:
                    entry.State = EntityState.Detached;
                    break;
            }
        }

        ChangeTracker.QueryTrackingBehavior = oldBehavoir;
        ChangeTracker.AutoDetectChangesEnabled = oldAutoDetect;
    }