EntityKey Class
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EntityKey Class

 

Provides a durable reference to an object that is an instance of an entity type.

Namespace:   System.Data
Assembly:  System.Data.Entity (in System.Data.Entity.dll)

System.Object
  System.Data.EntityKey

[SerializableAttribute]
[DataContractAttribute(IsReference = true)]
public sealed class EntityKey : IEquatable<EntityKey>

NameDescription
System_CAPS_pubmethodEntityKey()

Initializes a new instance of the EntityKey class.

System_CAPS_pubmethodEntityKey(String, IEnumerable<EntityKeyMember>)

Initializes a new instance of the EntityKey class with an entity set name and an IEnumerable<T> collection of EntityKeyMember objects.

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

Initializes a new instance of the EntityKey class with an entity set name and a generic T:System.Collections.Generic.KeyValuePair collection.

System_CAPS_pubmethodEntityKey(String, String, Object)

Initializes a new instance of the EntityKey class with an entity set name and specific entity key pair.

NameDescription
System_CAPS_pubpropertyEntityContainerName

Gets or sets the name of the entity container.

System_CAPS_pubpropertyEntityKeyValues

Gets or sets the key values associated with this EntityKey.

System_CAPS_pubpropertyEntitySetName

Gets or sets the name of the entity set.

System_CAPS_pubpropertyIsTemporary

Gets a value that indicates whether the EntityKey is temporary.

NameDescription
System_CAPS_pubmethodEquals(EntityKey)

Returns a value that indicates whether this instance is equal to a specified EntityKey.

System_CAPS_pubmethodEquals(Object)

Returns a value that indicates whether this instance is equal to a specified object. (Overrides Object.Equals(Object).)

System_CAPS_pubmethodGetEntitySet(MetadataWorkspace)

Gets the entity set for this entity key from the given metadata workspace.

System_CAPS_pubmethodGetHashCode()

Serves as a hash function for the current EntityKey object. GetHashCode is suitable for hashing algorithms and data structures such as a hash table.(Overrides Object.GetHashCode().)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethodOnDeserialized(StreamingContext)

Helper method that is used to deserialize an EntityKey.

System_CAPS_pubmethodOnDeserializing(StreamingContext)

Helper method that is used to deserialize an EntityKey.

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

NameDescription
System_CAPS_pubfieldSystem_CAPS_staticEntityNotValidKey

A simple EntityKey identifying an entity that resulted from a failed operation.

System_CAPS_pubfieldSystem_CAPS_staticNoEntitySetKey

A singleton EntityKey by which a read-only entity is identified.

NameDescription
System_CAPS_puboperatorSystem_CAPS_staticEquality(EntityKey, EntityKey)

Compares two EntityKey objects.

System_CAPS_puboperatorSystem_CAPS_staticInequality(EntityKey, EntityKey)

Compares two EntityKey objects.

The EntityKey objects are immutable; that is, after they are constructed they cannot be modified.

For more information, see Working with Entity Keys.

These examples are based on the AdventureWorks Sales Model. 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 (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 occured. Ensure that an object with the '{0}' key value exists.",
        orderId);
    }
}

.NET Framework
Available since 3.5

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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