EntityCollection<TEntity>.Add(TEntity) Método
Definição
Adiciona um objeto à coleção.Adds an object to the collection.
public:
virtual void Add(TEntity entity);
public void Add (TEntity entity);
override this.Add : 'Entity -> unit
Public Sub Add (entity As TEntity)
Parâmetros
- entity
- TEntity
Um objeto a ser adicionado à coleção.An object to add to the collection. O entity deve implementar IEntityWithRelationships.entity must implement IEntityWithRelationships.
Implementações
Exceções
entity é null.entity is null.
Exemplos
Este exemplo se baseia no modelo de vendas da Adventure Works.This example is based on the Adventure Works Sales Model. Para executar o código neste exemplo, você já deve ter adicionado o modelo de vendas AdventureWorks ao seu projeto e configurado seu projeto para usar o Entity Framework.To run the code in this example, you must have already added the AdventureWorks Sales Model to your project and configured your project to use the Entity Framework. Para fazer isso, conclua os procedimentos em como configurar manualmente um projeto de Entity Framework e como definir manualmente o modelo e os arquivos de mapeamento.To do this, complete the procedures in How to: Manually Configure an Entity Framework Project and How to: Manually Define the Model and Mapping Files.
Este exemplo cria duas novas SalesOrderHeader entidades, adiciona-as à Contact entidade e, depois de remover um objeto, usa o Add método para adicionar o objeto de volta à coleção.This example creates two new SalesOrderHeader entities, adds them to the Contact entity, and, after removing an object, uses the Add method to add the object back to the collection.
using (AdventureWorksEntities context =
new AdventureWorksEntities())
{
Contact contact = new Contact();
// Create a new SalesOrderHeader.
SalesOrderHeader newSalesOrder1 = new SalesOrderHeader();
// Add SalesOrderHeader to the Contact.
contact.SalesOrderHeaders.Add(newSalesOrder1);
// Create another SalesOrderHeader.
SalesOrderHeader newSalesOrder2 = new SalesOrderHeader();
// Add SalesOrderHeader to the Contact.
contact.SalesOrderHeaders.Add(newSalesOrder2);
// Get all related ends
IEnumerable<IRelatedEnd> relEnds =
((IEntityWithRelationships)contact)
.RelationshipManager.GetAllRelatedEnds();
foreach (IRelatedEnd relEnd in relEnds)
{
// Get Entity Collection from related end
EntityCollection<SalesOrderHeader> entityCollection =
(EntityCollection<SalesOrderHeader>)relEnd;
Console.WriteLine("EntityCollection count: {0}",
entityCollection.Count);
// Remove the first entity object.
entityCollection.Remove(newSalesOrder1);
bool contains = entityCollection.Contains(newSalesOrder1);
// Write the number of items after one entity has been removed
Console.WriteLine("EntityCollection count after one entity has been removed: {0}",
entityCollection.Count);
if (contains == false)
Console.WriteLine("The removed entity is not in in the collection any more.");
//Use IRelatedEnd to add the entity back.
relEnd.Add(newSalesOrder1);
Console.WriteLine("EntityCollection count after an entity has been added again: {0}",
entityCollection.Count);
}
}
Using context As New AdventureWorksEntities()
Dim contact As New Contact()
' Create a new SalesOrderHeader.
Dim newSalesOrder1 As New SalesOrderHeader()
' Add SalesOrderHeader to the Contact.
contact.SalesOrderHeaders.Add(newSalesOrder1)
' Create another SalesOrderHeader.
Dim newSalesOrder2 As New SalesOrderHeader()
' Add SalesOrderHeader to the Contact.
contact.SalesOrderHeaders.Add(newSalesOrder2)
' Get all related ends
Dim relEnds As IEnumerable(Of IRelatedEnd) = DirectCast(contact, IEntityWithRelationships).RelationshipManager.GetAllRelatedEnds()
For Each relEnd As IRelatedEnd In relEnds
' Get Entity Collection from related end
Dim entityCollection As EntityCollection(Of SalesOrderHeader) = DirectCast(relEnd, EntityCollection(Of SalesOrderHeader))
Console.WriteLine("EntityCollection count: {0}", entityCollection.Count)
' Remove the first entity object.
entityCollection.Remove(newSalesOrder1)
Dim contains As Boolean = entityCollection.Contains(newSalesOrder1)
' Write the number of items after one entity has been removed
Console.WriteLine("EntityCollection count after one entity has been removed: {0}", entityCollection.Count)
If contains = False Then
Console.WriteLine("The removed entity is not in in the collection any more.")
End If
'Use IRelatedEnd to add the entity back.
relEnd.Add(newSalesOrder1)
Console.WriteLine("EntityCollection count after an entity has been added again: {0}", entityCollection.Count)
Next
End Using
Comentários
O Add método adiciona um objeto a um EntityCollection<TEntity> e cria uma relação entre os dois objetos.The Add method adds an object to an EntityCollection<TEntity> and creates a relationship between the two objects. Quando o objeto de origem é anexado a uma ObjectContext instância, o Add método também adiciona o objeto ao ObjectContext .When the source object is attached to an ObjectContext instance, the Add method also adds the object to the ObjectContext. Esta operação é convertida em uma operação de inserção na fonte de dados quando SaveChanges é chamada.This operation is translated into an insert operation in the data source when SaveChanges is called. Para obter mais informações, consulte criando, adicionando, modificando e excluindo objetos.For more information, see Creating, Adding, Modifying, and Deleting Objects.
O Add método pode ser chamado várias vezes na mesma instância de objeto.The Add method can be called multiple times on the same object instance.