ObjectStateManager.TryGetObjectStateEntry メソッド

定義

特定のオブジェクトまたはリレーションシップ エントリの ObjectStateEntry オブジェクトを返します。Tries to return an ObjectStateEntry object for a specific object or relationship entry.

オーバーロード

TryGetObjectStateEntry(EntityKey, ObjectStateEntry)

指定された ObjectStateEntry のオブジェクトまたはリレーションシップに対応する EntityKey の取得を試みます。Tries to retrieve the corresponding ObjectStateEntry for the object or relationship with the specified EntityKey.

TryGetObjectStateEntry(Object, ObjectStateEntry)

指定された ObjectStateEntry に対応する Object の取得を試みます。Tries to retrieve the corresponding ObjectStateEntry for the specified Object.

TryGetObjectStateEntry(EntityKey, ObjectStateEntry)

指定された ObjectStateEntry のオブジェクトまたはリレーションシップに対応する EntityKey の取得を試みます。Tries to retrieve the corresponding ObjectStateEntry for the object or relationship with the specified EntityKey.

public:
 bool TryGetObjectStateEntry(System::Data::EntityKey ^ key, [Runtime::InteropServices::Out] System::Data::Objects::ObjectStateEntry ^ % entry);
public bool TryGetObjectStateEntry (System.Data.EntityKey key, out System.Data.Objects.ObjectStateEntry entry);
member this.TryGetObjectStateEntry : System.Data.EntityKey * ObjectStateEntry -> bool
Public Function TryGetObjectStateEntry (key As EntityKey, ByRef entry As ObjectStateEntry) As Boolean

パラメーター

key
EntityKey

指定した EntityKeyThe given EntityKey.

entry
ObjectStateEntry

このメソッドが返されるときに、指定した ObjectStateEntryEntityKey を格納します。このパラメーターは初期化せずに渡されます。When this method returns, contains an ObjectStateEntry for the given EntityKey This parameter is passed uninitialized.

戻り値

指定された ObjectStateEntry に対応する EntityKey が存在する場合は true のブール値。それ以外の場合は falseA Boolean value that is true if there is a corresponding ObjectStateEntry for the given EntityKey; otherwise, false.

例外

null (Visual Basic では Nothing) 値は key に提供されます。A null (Nothing in Visual Basic) value is provided for key.

このトピックの例は、 AdventureWorks Sales Modelに基づいています。The examples in this topic are based on the AdventureWorks Sales Model.

この例では、指定された ObjectStateEntry に対応する EntityKey の取得を試みます。The example attempts to retrieve the corresponding ObjectStateEntry for the given EntityKey.

int orderId = 43680;

using (AdventureWorksEntities context =
    new AdventureWorksEntities())
{
    ObjectStateManager objectStateManager = context.ObjectStateManager;
    ObjectStateEntry stateEntry = null;

    var order = (from o in context.SalesOrderHeaders
                 where o.SalesOrderID == orderId
                 select o).First();

    // Attempts to retrieve ObjectStateEntry for the given EntityKey.
    bool isPresent = objectStateManager.TryGetObjectStateEntry(((IEntityWithKey)order).EntityKey, out stateEntry);
    if (isPresent)
    {
        Console.WriteLine("The entity was found");
    }
}
Dim orderId As Integer = 43680

Using context As New AdventureWorksEntities()
    Dim objectStateManager As ObjectStateManager = context.ObjectStateManager
    Dim stateEntry As ObjectStateEntry = Nothing

    Dim order = (From o In context.SalesOrderHeaders
        Where o.SalesOrderID = orderId
        Select o).First()

    ' Attempts to retrieve ObjectStateEntry for the given EntityKey. 
    Dim isPresent As Boolean = objectStateManager.TryGetObjectStateEntry(DirectCast(order, IEntityWithKey).EntityKey, stateEntry)
    If isPresent Then
        Console.WriteLine("The entity was found")
    End If
End Using

次の例では、返された TryGetObjectStateEntry(EntityKey, ObjectStateEntry)ObjectStateManager メソッドを使用して、エンティティ キーに基づいてオブジェクトを取得します。The following example uses the TryGetObjectStateEntry(EntityKey, ObjectStateEntry) method on the returned ObjectStateManager to get an object based on its entity key.

private static void ApplyItemUpdates(SalesOrderDetail originalItem,
    SalesOrderDetail updatedItem)
{
    using (AdventureWorksEntities context =
        new AdventureWorksEntities())
    {
        context.SalesOrderDetails.Attach(updatedItem);
        // Check if the ID is 0, if it is the item is new. 
        // In this case we need to chage the state to Added.
        if (updatedItem.SalesOrderDetailID == 0)
        {
            // Because the ID is generated by the database we do not need to
            // set updatedItem.SalesOrderDetailID.
            context.ObjectStateManager.ChangeObjectState(updatedItem, System.Data.EntityState.Added);
        }
        else
        {
            // If the SalesOrderDetailID is not 0, then the item is not new
            // and needs to be updated. Because we already added the 
            // updated object to the context we need to apply the original values.
            // If we attached originalItem to the context 
            // we would need to apply the current values:
            // context.ApplyCurrentValues("SalesOrderDetails", updatedItem);
            // Applying current or original values, changes the state 
            // of the attached object to Modified.
            context.ApplyOriginalValues("SalesOrderDetails", originalItem);
        }
        context.SaveChanges();
    }
}
Private Shared Sub ApplyItemUpdates(ByVal originalItem As SalesOrderDetail, ByVal updatedItem As SalesOrderDetail)
    Using context As New AdventureWorksEntities()
        context.SalesOrderDetails.Attach(updatedItem)
        ' Check if the ID is 0, if it is the item is new. 
        ' In this case we need to chage the state to Added. 
        If updatedItem.SalesOrderDetailID = 0 Then
            ' Because the ID is generated by the database we do not need to 
            ' set updatedItem.SalesOrderDetailID. 
            context.ObjectStateManager.ChangeObjectState(updatedItem, System.Data.EntityState.Added)
        Else
            ' If the SalesOrderDetailID is not 0, then the item is not new 
            ' and needs to be updated. Because we already added the 
            ' updated object to the context we need to apply the original values. 
            ' If we attached originalItem to the context 
            ' we would need to apply the current values: 
            ' context.ApplyCurrentValues("SalesOrderDetails", updatedItem); 
            ' Applying current or original values, changes the state 
            ' of the attached object to Modified. 
            context.ApplyOriginalValues("SalesOrderDetails", originalItem)
        End If
        context.SaveChanges()
    End Using
End Sub

注釈

TryGetObjectStateEntry(EntityKey, ObjectStateEntry) を使用して、ObjectStateEntry メソッドで発生した InvalidOperationException を処理せずに、GetObjectStateEntry(EntityKey) を返します。Use TryGetObjectStateEntry(EntityKey, ObjectStateEntry) to return an ObjectStateEntry without having to handle the InvalidOperationException raised by the GetObjectStateEntry(EntityKey) method.

TryGetObjectStateEntry(Object, ObjectStateEntry)

指定された ObjectStateEntry に対応する Object の取得を試みます。Tries to retrieve the corresponding ObjectStateEntry for the specified Object.

public:
 bool TryGetObjectStateEntry(System::Object ^ entity, [Runtime::InteropServices::Out] System::Data::Objects::ObjectStateEntry ^ % entry);
public bool TryGetObjectStateEntry (object entity, out System.Data.Objects.ObjectStateEntry entry);
member this.TryGetObjectStateEntry : obj * ObjectStateEntry -> bool
Public Function TryGetObjectStateEntry (entity As Object, ByRef entry As ObjectStateEntry) As Boolean

パラメーター

entity
Object

取得した Object が属する ObjectStateEntryThe Object to which the retrieved ObjectStateEntry belongs.

entry
ObjectStateEntry

このメソッドから制御が戻った時点で、指定された ObjectStateEntryEntityKey が格納されます。このパラメーターは初期化されていない状態で渡されます。When this method returns, contains the ObjectStateEntry for the given EntityKey This parameter is passed uninitialized.

戻り値

ブール値。指定されたオブジェクトに対応する ObjectStateEntry が存在する場合は true。それ以外の場合は falseA Boolean value that is true if there is a corresponding ObjectStateEntry for the given object; otherwise, false.

注釈

TryGetObjectStateEntry(Object, ObjectStateEntry) メソッドを使用して、ObjectStateEntry メソッドで発生した InvalidOperationException を処理せずに、GetObjectStateEntry(Object) を返します。Use the TryGetObjectStateEntry(Object, ObjectStateEntry) method to return an ObjectStateEntry without having to handle the InvalidOperationException raised by the GetObjectStateEntry(Object) method.

適用対象