EntityCollection<TEntity>.Add(TEntity) Método

Definición

Agrega un objeto a la colección.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)

Parámetros

entity
TEntity

Objeto que se va a agregar a la colección.An object to add to the collection. entity debe implementar IEntityWithRelationships.entity must implement IEntityWithRelationships.

Implementaciones

Excepciones

entity es null.entity is null.

Ejemplos

Este ejemplo se basa en el .This example is based on the . Para ejecutar el código de este ejemplo, debe haber agregado ya el modelo AdventureWorks Sales al proyecto y haber configurado el proyecto para que use 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 ello, complete los procedimientos que se describen en Cómo: configurar manualmente un proyecto de Entity Framework y cómo definir manualmente los archivos de asignación y de modelo.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.

En este ejemplo se crean dos nuevas entidades SalesOrderHeader, se agregan a la entidad Contact y, después de quitar un objeto, se usa el método Add para volver a agregar el objeto a la colección.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

Comentarios

El método Add agrega un objeto a una EntityCollection<TEntity> y crea una relación entre los dos objetos.The Add method adds an object to an EntityCollection<TEntity> and creates a relationship between the two objects. Cuando se asocia el objeto de origen a una instancia de ObjectContext, el método Add también agrega el objeto al ObjectContext.When the source object is attached to an ObjectContext instance, the Add method also adds the object to the ObjectContext. Esta operación se convierte en una operación de inserción en el origen de datos cuando se llama a SaveChanges.This operation is translated into an insert operation in the data source when SaveChanges is called. Para obtener más información, vea crear, agregar, modificar y eliminar objetos.For more information, see Creating, Adding, Modifying, and Deleting Objects.

Se puede llamar al método Add varias veces en la misma instancia de objeto.The Add method can be called multiple times on the same object instance.

Se aplica a