EntityKey EntityKey EntityKey EntityKey Class

Definição

Fornece uma referência durável a um objeto que é uma instância de um tipo de entidade.Provides a durable reference to an object that is an instance of an entity type.

public ref class EntityKey sealed : IEquatable<System::Data::EntityKey ^>
[System.Runtime.Serialization.DataContract(IsReference=true)]
[System.Serializable]
public sealed class EntityKey : IEquatable<System.Data.EntityKey>
type EntityKey = class
    interface IEquatable<EntityKey>
Public NotInheritable Class EntityKey
Implements IEquatable(Of EntityKey)
Herança
EntityKeyEntityKeyEntityKeyEntityKey
Atributos
Implementações

Exemplos

Esses exemplos são baseados no modelo de vendas AdventureWorks.These examples are based on the AdventureWorks Sales Model. Os exemplos mostram como criar e usar um EntityKey.The examples show you how to create and use an EntityKey.

using (AdventureWorksEntities context =
    new AdventureWorksEntities())
{
    Object entity = null;
    IEnumerable<KeyValuePair<string, object>> entityKeyValues =
        new KeyValuePair<string, object>[] {
            new KeyValuePair<string, object>("SalesOrderID", 43680) };

    // Create the  key for a specific SalesOrderHeader object. 
    EntityKey key = new EntityKey("AdventureWorksEntities.SalesOrderHeaders", entityKeyValues);

    // Get the object from the context or the persisted store by its key.
    if (context.TryGetObjectByKey(key, out entity))
    {
        Console.WriteLine("The requested " + entity.GetType().FullName +
            " object was found");
    }
    else
    {
        Console.WriteLine("An object with this key " +
            "could not be found.");
    }
}
Using context As New AdventureWorksEntities()
    Dim entity As Object = Nothing
    Dim entityKeyValues As IEnumerable(Of KeyValuePair(Of String, Object)) = _
        New KeyValuePair(Of String, Object)() {New KeyValuePair(Of String, Object)("SalesOrderID", 43680)}

    ' Create the key for a specific SalesOrderHeader object. 
    Dim key As New EntityKey("AdventureWorksEntities.SalesOrderHeaders", entityKeyValues)

    ' Get the object from the context or the persisted store by its key. 
    If context.TryGetObjectByKey(key, entity) Then
        Console.WriteLine("The requested " & entity.GetType().FullName & " object was found")
    Else
        Console.WriteLine("An object with this key could not be found.")
    End If
End Using
using (AdventureWorksEntities context =
    new AdventureWorksEntities())
{
    try
    {
        // Create the key that represents the order.
        EntityKey orderKey =
            new EntityKey("AdventureWorksEntities.SalesOrderHeaders",
                "SalesOrderID", orderId);

        // Create the stand-in SalesOrderHeader object
        // based on the specified SalesOrderID.
        SalesOrderHeader order = new SalesOrderHeader();
        order.EntityKey = orderKey;

        // Assign the ID to the SalesOrderID property to matche the key.
        order.SalesOrderID = (int)orderKey.EntityKeyValues[0].Value;

        // Attach the stand-in SalesOrderHeader object.
        context.SalesOrderHeaders.Attach(order);

        // Create a new SalesOrderDetail object.
        // You can use the static CreateObjectName method (the Entity Framework
        // adds this method to the generated entity types) instead of the new operator:
        // SalesOrderDetail.CreateSalesOrderDetail(1, 0, 2, 750, 1, (decimal)2171.2942, 0, 0,
        //                                         Guid.NewGuid(), DateTime.Today));
        SalesOrderDetail detail = new SalesOrderDetail
        {
            SalesOrderID = orderId,
            SalesOrderDetailID = 0,
            OrderQty = 2,
            ProductID = 750,
            SpecialOfferID = 1,
            UnitPrice = (decimal)2171.2942,
            UnitPriceDiscount = 0,
            LineTotal = 0,
            rowguid = Guid.NewGuid(),
            ModifiedDate = DateTime.Now
        };

        order.SalesOrderDetails.Add(detail);

        context.SaveChanges();
    }
    catch (InvalidOperationException)
    {
        Console.WriteLine("Ensure that the key value matches the value of the object's ID property.");
    }
    catch (UpdateException)
    {
        Console.WriteLine("An error has occurred. Ensure that an object with the '{0}' key value exists.",
        orderId);
    }
}
Using context As New AdventureWorksEntities()
    Try
        ' Create the key that represents the order. 
        Dim orderKey As New EntityKey("AdventureWorksEntities.SalesOrderHeaders", "SalesOrderID", orderId)

        ' Create the stand-in SalesOrderHeader object 
        ' based on the specified SalesOrderID. 
        Dim order As New SalesOrderHeader()
        order.EntityKey = orderKey

        ' Assign the ID to the SalesOrderID property to matche the key. 
        order.SalesOrderID = CInt(orderKey.EntityKeyValues(0).Value)

        ' Attach the stand-in SalesOrderHeader object. 
        context.SalesOrderHeaders.Attach(order)

        ' Create a new SalesOrderDetail object. 
        ' You can use the static CreateObjectName method (the Entity Framework 
        ' adds this method to the generated entity types) instead of the new operator: 
        ' SalesOrderDetail.CreateSalesOrderDetail(1, 0, 2, 750, 1, (decimal)2171.2942, 0, 0, 
        ' Guid.NewGuid(), DateTime.Today)); 
        Dim detail = New SalesOrderDetail With
        {
            .SalesOrderID = 0,
            .SalesOrderDetailID = 0,
            .OrderQty = 2,
            .ProductID = 750,
            .SpecialOfferID = 1,
            .UnitPrice = CDec(2171.2942),
            .UnitPriceDiscount = 0,
            .LineTotal = 0,
            .rowguid = Guid.NewGuid(),
            .ModifiedDate = DateTime.Now
        }

        order.SalesOrderDetails.Add(detail)

        context.SaveChanges()
    Catch generatedExceptionName As InvalidOperationException
        Console.WriteLine("Ensure that the key value matches the value of the object's ID property.")
    Catch generatedExceptionName As UpdateException
        Console.WriteLine("An error has occurred. Ensure that an object with the '{0}' key value exists.", orderId)
    End Try
End Using

Comentários

Os EntityKey objetos são imutáveis; ou seja, após serem construídos, eles não podem ser modificados.The EntityKey objects are immutable; that is, after they are constructed they cannot be modified.

Para obter mais informações, consulte trabalhando com chaves de entidade.For more information, see Working with Entity Keys.

Construtores

EntityKey() EntityKey() EntityKey() EntityKey()

Inicializa uma nova instância da classe EntityKey.Initializes a new instance of the EntityKey class.

EntityKey(String, IEnumerable<EntityKeyMember>) EntityKey(String, IEnumerable<EntityKeyMember>) EntityKey(String, IEnumerable<EntityKeyMember>) EntityKey(String, IEnumerable<EntityKeyMember>)

Inicializa uma nova instância da classe EntityKey com um nome de conjunto de entidades e uma coleção IEnumerable<T> de objetos EntityKeyMember.Initializes a new instance of the EntityKey class with an entity set name and an IEnumerable<T> collection of EntityKeyMember objects.

EntityKey(String, IEnumerable<KeyValuePair<String,Object>>) EntityKey(String, IEnumerable<KeyValuePair<String,Object>>) EntityKey(String, IEnumerable<KeyValuePair<String,Object>>) EntityKey(String, IEnumerable<KeyValuePair<String,Object>>)

Inicializa uma nova instância da classe EntityKey com um nome de conjunto de entidades e uma coleção KeyValuePair genérica.Initializes a new instance of the EntityKey class with an entity set name and a generic KeyValuePair collection.

EntityKey(String, String, Object) EntityKey(String, String, Object) EntityKey(String, String, Object) EntityKey(String, String, Object)

Inicializa uma nova instância da classe EntityKey com um nome de conjunto de entidades e um par de chave de entidade específico.Initializes a new instance of the EntityKey class with an entity set name and specific entity key pair.

Campos

EntityNotValidKey EntityNotValidKey EntityNotValidKey EntityNotValidKey

Um simples EntityKey que identifica uma entidade resultante de uma operação TREAT com falha.A simple EntityKey identifying an entity that resulted from a failed TREAT operation.

NoEntitySetKey NoEntitySetKey NoEntitySetKey NoEntitySetKey

Um singleton EntityKey pelo qual uma entidade somente leitura é identificada.A singleton EntityKey by which a read-only entity is identified.

Propriedades

EntityContainerName EntityContainerName EntityContainerName EntityContainerName

Obtém ou define o nome do contêiner de entidade.Gets or sets the name of the entity container.

EntityKeyValues EntityKeyValues EntityKeyValues EntityKeyValues

Obtém ou define os valores de chave associados a essa EntityKey.Gets or sets the key values associated with this EntityKey.

EntitySetName EntitySetName EntitySetName EntitySetName

Obtém ou define o nome do conjunto de entidades.Gets or sets the name of the entity set.

IsTemporary IsTemporary IsTemporary IsTemporary

Obtém um valor que indica se o EntityKey é temporário.Gets a value that indicates whether the EntityKey is temporary.

Métodos

Equals(EntityKey) Equals(EntityKey) Equals(EntityKey) Equals(EntityKey)

Retorna um valor que indica se essa instância é igual a um EntityKey especificado.Returns a value that indicates whether this instance is equal to a specified EntityKey.

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Retorna um valor que indica se essa instância é igual a um objeto especificado.Returns a value that indicates whether this instance is equal to a specified object.

GetEntitySet(MetadataWorkspace) GetEntitySet(MetadataWorkspace) GetEntitySet(MetadataWorkspace) GetEntitySet(MetadataWorkspace)

Obtém a conjunto de entidades para essa chave de entidade do workspace de metadados fornecido.Gets the entity set for this entity key from the given metadata workspace.

GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Serve como uma função de hash para o objeto EntityKey atual.Serves as a hash function for the current EntityKey object. GetHashCode() é adequado para algoritmos de hash e estruturas de dados como uma tabela de hash.GetHashCode() is suitable for hashing algorithms and data structures such as a hash table.

GetType() GetType() GetType() GetType()

Obtém o Type da instância atual.Gets the Type of the current instance.

(Inherited from Object)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

Cria uma cópia superficial do Object atual.Creates a shallow copy of the current Object.

(Inherited from Object)
OnDeserialized(StreamingContext) OnDeserialized(StreamingContext) OnDeserialized(StreamingContext) OnDeserialized(StreamingContext)

Método auxiliar que é usado para desserializar um EntityKey.Helper method that is used to deserialize an EntityKey.

OnDeserializing(StreamingContext) OnDeserializing(StreamingContext) OnDeserializing(StreamingContext) OnDeserializing(StreamingContext)

Método auxiliar que é usado para desserializar um EntityKey.Helper method that is used to deserialize an EntityKey.

ToString() ToString() ToString() ToString()

Retorna uma cadeia de caracteres que representa o objeto atual.Returns a string that represents the current object.

(Inherited from Object)

Operadores

Equality(EntityKey, EntityKey) Equality(EntityKey, EntityKey) Equality(EntityKey, EntityKey) Equality(EntityKey, EntityKey)

Compara dois objetos EntityKey.Compares two EntityKey objects.

Inequality(EntityKey, EntityKey) Inequality(EntityKey, EntityKey) Inequality(EntityKey, EntityKey) Inequality(EntityKey, EntityKey)

Compara dois objetos EntityKey.Compares two EntityKey objects.

Aplica-se a