EntityCollection<TEntity>.Add(TEntity) Méthode

Définition

Ajoute un objet à la collection.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)

Paramètres

entity
TEntity

Objet à ajouter à la collection.An object to add to the collection. entity doit implémenter IEntityWithRelationships.entity must implement IEntityWithRelationships.

Implémente

Exceptions

entity est null.entity is null.

Exemples

Cet exemple est basé sur.This example is based on the . Pour exécuter le code de cet exemple, vous devez déjà avoir ajouté le modèle de vente AdventureWorks Sales Model à votre projet et configuré ce dernier pour qu’il utilise 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. Pour ce faire, effectuez les procédures décrites dans la rubrique Procédure : Configurez manuellement un projet Entity Framework et procédez comme suit : Définissez manuellement les fichiersde modèle et de mappage.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.

Cet exemple crée deux nouvelles entités SalesOrderHeader, les ajoute à l’entité Contact et, après avoir supprimé un objet, utilise la méthode Add pour rajouter l’objet à la collection.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

Remarques

La méthode Add ajoute un objet à un objet EntityCollection<TEntity> et crée une relation entre les deux objets.The Add method adds an object to an EntityCollection<TEntity> and creates a relationship between the two objects. Lorsque l'objet source est attaché à une instance ObjectContext instance, la méthode Add ajoute également l'objet à l'objet ObjectContext.When the source object is attached to an ObjectContext instance, the Add method also adds the object to the ObjectContext. Cette opération est traduite en opération d'insertion dans la source de données lorsque SaveChanges est appelée.This operation is translated into an insert operation in the data source when SaveChanges is called. Pour plus d’informations, consultez création, ajout, modification et suppression d’objets.For more information, see Creating, Adding, Modifying, and Deleting Objects.

La méthode Add peut être appelée plusieurs fois sur la même instance d'objet.The Add method can be called multiple times on the same object instance.

S’applique à