ObjectContext.ObjectStateManager Propriedade

Definição

Espaço de Nomes:
System.Data.Objects
Assemblagem:
System.Data.Entity.dll

Obtém o gestor de estado do objeto usado pelo contexto do objeto para acompanhar as alterações do objeto.

public:
 property System::Data::Objects::ObjectStateManager ^ ObjectStateManager { System::Data::Objects::ObjectStateManager ^ get(); };
public System.Data.Objects.ObjectStateManager ObjectStateManager { get; }
member this.ObjectStateManager : System.Data.Objects.ObjectStateManager
Public ReadOnly Property ObjectStateManager As ObjectStateManager

Valor de Propriedade

ObjectStateManager

O ObjectStateManager utilizado por este ObjectContext.

Exemplos

Este exemplo obtém o ObjectStateManager de e ObjectContext usa o gestor de estados para aceder a um objeto no contexto.

int orderId = 43680;

using (AdventureWorksEntities context =
    new AdventureWorksEntities())
{
    ObjectStateManager objectStateManager = context.ObjectStateManager;
    ObjectStateEntry stateEntry = null;

    var order = (from o in context.SalesOrderHeaders
                 where o.SalesOrderID == orderId
                 select o).First();

    // Attempts to retrieve ObjectStateEntry for the given EntityKey.
    bool isPresent = objectStateManager.TryGetObjectStateEntry(((IEntityWithKey)order).EntityKey, out stateEntry);
    if (isPresent)
    {
        Console.WriteLine("The entity was found");
    }
}

Este exemplo usa o TryGetObjectStateEntry método no retorno ObjectStateManager para obter um objeto com base na sua chave de entidade.

private static void ApplyItemUpdates(SalesOrderDetail originalItem,
    SalesOrderDetail updatedItem)
{
    using (AdventureWorksEntities context =
        new AdventureWorksEntities())
    {
        context.SalesOrderDetails.Attach(updatedItem);
        // Check if the ID is 0, if it is the item is new.
        // In this case we need to chage the state to Added.
        if (updatedItem.SalesOrderDetailID == 0)
        {
            // Because the ID is generated by the database we do not need to
            // set updatedItem.SalesOrderDetailID.
            context.ObjectStateManager.ChangeObjectState(updatedItem, System.Data.EntityState.Added);
        }
        else
        {
            // If the SalesOrderDetailID is not 0, then the item is not new
            // and needs to be updated. Because we already added the
            // updated object to the context we need to apply the original values.
            // If we attached originalItem to the context
            // we would need to apply the current values:
            // context.ApplyCurrentValues("SalesOrderDetails", updatedItem);
            // Applying current or original values, changes the state
            // of the attached object to Modified.
            context.ApplyOriginalValues("SalesOrderDetails", originalItem);
        }
        context.SaveChanges();
    }
}

Aplica-se a

Ver também