EntityCollection<TEntity>.Contains(TEntity) Méthode

Définition

Détermine si un objet spécifique existe dans la collection.Determines whether a specific object exists in the collection.

public:
 virtual bool Contains(TEntity entity);
public bool Contains (TEntity entity);
abstract member Contains : 'Entity -> bool
override this.Contains : 'Entity -> bool
Public Function Contains (entity As TEntity) As Boolean

Paramètres

entity
TEntity

Objet à rechercher dans EntityCollection<TEntity>.The object to locate in the EntityCollection<TEntity>.

Retours

true si l'objet est trouvé dans EntityCollection<TEntity> ; sinon, false.true if the object is found in the EntityCollection<TEntity>; otherwise, false.

Implémente

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.

L'exemple réalise les actions suivantes :This example does the following:

  1. Crée deux nouvelles entités SalesOrderHeader et les ajoute à l'entité Contact.Creates two new SalesOrderHeader entities and adds them to the Contact entity.

  2. Obtient toutes les terminaisons connexes à partir de l'objet RelationshipManager associé à l'entité Contact.Gets all related ends from the RelationshipManager that is associated with the Contact entity.

  3. Itère au sein de la collection d'objets IRelatedEnd.Iterates through the collection of IRelatedEnds.

  4. Obtient l'objet EntityCollection<TEntity> pour chaque terminaison connexe.Gets the EntityCollection<TEntity> for each related end.

  5. Utilise la méthode Remove pour déplacer l’une des entités à partir de la collection.Uses the Remove method to remove one of the entities from the collection.

  6. Appelle la méthode Contains pour déterminer si l'objet a été supprimé de la collection.Calls the Contains method to determine whether the object was removed from the collection.

  7. Utilise la méthode Add pour rajouter l'entité.Uses the Add method to add the entity back.

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

Utilise la méthode Object.Equals pour comparer l’objet spécifié aux objets déjà dans la collection.Uses the Object.Equals method to compare the specified object with the objects already in the collection.

S’applique à