EntityKey 构造函数

定义

命名空间:: System.Data

程序集:: System.Data.Entity.dll

重要

一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。

初始化 EntityKey 类的新实例。

重载

名称	说明
EntityKey()	初始化 EntityKey 类的新实例。
EntityKey(String, IEnumerable<KeyValuePair<String,Object>>)	使用实体集名称和泛型EntityKey集合初始化类的新实例KeyValuePair。
EntityKey(String, IEnumerable<EntityKeyMember>)	使用实体集名称和EntityKey对象的集合IEnumerable<T>初始化类的新实例EntityKeyMember。
EntityKey(String, String, Object)	使用实体集名称和特定实体密钥对初始化类的新实例 EntityKey 。

EntityKey()

初始化 EntityKey 类的新实例。

public:
 EntityKey();

public EntityKey();

Public Sub New ()

适用于

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

使用实体集名称和泛型EntityKey集合初始化类的新实例KeyValuePair。

public:
 EntityKey(System::String ^ qualifiedEntitySetName, System::Collections::Generic::IEnumerable<System::Collections::Generic::KeyValuePair<System::String ^, System::Object ^>> ^ entityKeyValues);

public EntityKey(string qualifiedEntitySetName, System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<string,object>> entityKeyValues);

new System.Data.EntityKey : string * seq<System.Collections.Generic.KeyValuePair<string, obj>> -> System.Data.EntityKey

Public Sub New (qualifiedEntitySetName As String, entityKeyValues As IEnumerable(Of KeyValuePair(Of String, Object)))

参数

qualifiedEntitySetName: String

一个 String 实体集名称，由实体容器名称限定。

entityKeyValues: IEnumerable<KeyValuePair<String,Object>>

泛型 KeyValuePair 集合。

每个键/值对都有一个属性名称作为键，该属性的值作为值。每个属性应有一对，该对是该属性的 EntityKey一部分。键/值对的顺序并不重要，但应包括每个键属性。属性名称是未使用实体类型名称或架构名称限定的简单名称。

示例

此示例演示如何创建和使用 EntityKey.

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);
    }
}

适用于

EntityKey(String, IEnumerable<EntityKeyMember>)

使用实体集名称和EntityKey对象的集合IEnumerable<T>初始化类的新实例EntityKeyMember。

public:
 EntityKey(System::String ^ qualifiedEntitySetName, System::Collections::Generic::IEnumerable<System::Data::EntityKeyMember ^> ^ entityKeyValues);

public EntityKey(string qualifiedEntitySetName, System.Collections.Generic.IEnumerable<System.Data.EntityKeyMember> entityKeyValues);

new System.Data.EntityKey : string * seq<System.Data.EntityKeyMember> -> System.Data.EntityKey

Public Sub New (qualifiedEntitySetName As String, entityKeyValues As IEnumerable(Of EntityKeyMember))

参数

qualifiedEntitySetName: String

一个 String 实体集名称，由实体容器名称限定。

entityKeyValues: IEnumerable<EntityKeyMember>

用于 IEnumerable<T> 初始化键的对象集合 EntityKeyMember 。

适用于

EntityKey(String, String, Object)

使用实体集名称和特定实体密钥对初始化类的新实例 EntityKey 。

public:
 EntityKey(System::String ^ qualifiedEntitySetName, System::String ^ keyName, System::Object ^ keyValue);

public EntityKey(string qualifiedEntitySetName, string keyName, object keyValue);

new System.Data.EntityKey : string * string * obj -> System.Data.EntityKey

Public Sub New (qualifiedEntitySetName As String, keyName As String, keyValue As Object)

参数

qualifiedEntitySetName: String

一个 String 实体集名称，由实体容器名称限定。

keyName: String

一个 String 是密钥的名称。

keyValue: Object

一个 Object 是键值。

示例

此示例演示如何创建和使用 EntityKey.

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);
    }
}

适用于

反馈

此页面是否有帮助？