方法: エンティティを追加、変更、および削除する (WCF Data Services)

WCF Data Services クライアント ライブラリでは、DataServiceContext のオブジェクトで同等のアクションを実行して、データ サービスのエンティティ データを作成、更新、および削除できます。 詳細については、「データ サービスの更新 (WCF Data Services)」を参照してください。

このトピックの例では、Northwind サンプル データ サービスおよび自動生成されたクライアント データ サービス クラスを使用します。 このサービスおよびクライアント データ クラスは、WCF Data Services クイック スタートを完了したときに作成されます。

例

次の例では、新しいオブジェクト インスタンスを作成し、DataServiceContext で AddObject メソッドを呼び出してコンテキスト内に項目を作成します。 SaveChanges メソッドが呼び出されたときに HTTP POST メッセージがデータ サービスに送信されます。

' Create the DataServiceContext using the service URI.
Dim context = New NorthwindEntities(svcUri)

' Create the new product.
Dim newProduct = _
    Product.CreateProduct(0, "White Tea - loose", False)

' Set property values.
newProduct.QuantityPerUnit = "120gm bags"
newProduct.ReorderLevel = 5
newProduct.UnitPrice = 5.2D

Try
    ' Add the new product to the Products entity set.
    context.AddToProducts(newProduct)

    ' Send the insert to the data service.
    context.SaveChanges()

    Console.WriteLine("New product added with ID {0}.", newProduct.ProductID)
Catch ex As DataServiceRequestException
    Throw New ApplicationException( _
            "An error occurred when saving changes.", ex)

// Create the DataServiceContext using the service URI.
NorthwindEntities context = new NorthwindEntities(svcUri);

// Create the new product.
Product newProduct =
    Product.CreateProduct(0, "White Tea - loose", false);

// Set property values.
newProduct.QuantityPerUnit = "120gm bags";
newProduct.ReorderLevel = 5;
newProduct.UnitPrice = 5.2M;

try
{
    // Add the new product to the Products entity set.
    context.AddToProducts(newProduct);

    // Send the insert to the data service.
    context.SaveChanges();

    Console.WriteLine("New product added with ID {0}.", newProduct.ProductID);
}
catch (DataServiceRequestException ex)
{
    throw new ApplicationException(
        "An error occurred when saving changes.", ex);
}

次の例では、既存のオブジェクトを取得および変更し、DataServiceContext で UpdateObject メソッドを呼び出してコンテキスト内の項目を Updated としてマークします。 SaveChanges メソッドが呼び出されたとき HTTP MERGE メッセージがデータ サービスに送信されます。

Dim customerId = "ALFKI"

' Create the DataServiceContext using the service URI.
Dim context = New NorthwindEntities(svcUri)

' Get a customer to modify using the supplied ID.
Dim customerToChange = (From customer In context.Customers _
                        Where customer.CustomerID = customerId _
                        Select customer).Single()

' Change some property values.
customerToChange.CompanyName = "Alfreds Futterkiste"
customerToChange.ContactName = "Maria Anders"
customerToChange.ContactTitle = "Sales Representative"

Try
    ' Mark the customer as updated.
    context.UpdateObject(customerToChange)

    ' Send the update to the data service.
    context.SaveChanges()
Catch ex As DataServiceRequestException
    Throw New ApplicationException( _
            "An error occurred when saving changes.", ex)
End Try

string customerId = "ALFKI";

// Create the DataServiceContext using the service URI.
NorthwindEntities context = new NorthwindEntities(svcUri);

// Get a customer to modify using the supplied ID.
var customerToChange = (from customer in context.Customers
                        where customer.CustomerID == customerId
                        select customer).Single();
 
// Change some property values.
customerToChange.CompanyName = "Alfreds Futterkiste";
customerToChange.ContactName = "Maria Anders";
customerToChange.ContactTitle = "Sales Representative";

try
{
    // Mark the customer as updated.
    context.UpdateObject(customerToChange);

    // Send the update to the data service.
    context.SaveChanges();
}
catch (DataServiceRequestException  ex)
{
    throw new ApplicationException(
        "An error occurred when saving changes.", ex);
}

次の例では、DataServiceContext で DeleteObject メソッドを呼び出して、コンテキスト内の項目を Deleted とマークします。 SaveChanges メソッドが呼び出されたとき HTTP DELETE メッセージがデータ サービスに送信されます。

' Create the DataServiceContext using the service URI.
Dim context = New NorthwindEntities(svcUri)

Try
    ' Get the product to delete, by product ID.
    Dim deletedProduct = (From product In context.Products _
                          Where product.ProductID = productID _
                          Select product).Single()


    ' Mark the product for deletion.    
    context.DeleteObject(deletedProduct)

    ' Send the delete to the data service.
    context.SaveChanges()

    ' Handle the error that occurs when the delete operation fails,
    ' which can happen when there are entities with existing 
    ' relationships to the product being deleted.
Catch ex As DataServiceRequestException
    Throw New ApplicationException( _
            "An error occurred when saving changes.", ex)
End Try

// Create the DataServiceContext using the service URI.
NorthwindEntities context = new NorthwindEntities(svcUri);

try
{
    // Get the product to delete, by product ID.
    var deletedProduct = (from product in context.Products
                          where product.ProductID == productID
                          select product).Single();

    // Mark the product for deletion.    
    context.DeleteObject(deletedProduct);

    // Send the delete to the data service.
    context.SaveChanges();
}
// Handle the error that occurs when the delete operation fails,
// which can happen when there are entities with existing 
// relationships to the product being deleted.
catch (DataServiceRequestException ex)
{
    throw new ApplicationException(
        "An error occurred when saving changes.", ex);
}

次の例では、新しいオブジェクト インスタンスを作成し、DataServiceContext で AddRelatedObject メソッドを呼び出して、関連する注文へのリンクと共に、コンテキスト内に項目を作成します。 SaveChanges メソッドが呼び出されたときに HTTP POST メッセージがデータ サービスに送信されます。

Dim productId = 25
Dim customerId = "ALFKI"

Dim newItem As Order_Detail = Nothing

' Create the DataServiceContext using the service URI.
Dim context = New NorthwindEntities(svcUri)

Try
    ' Get the specific product.
    Dim selectedProduct = (From product In context.Products _
                           Where product.ProductID = productId _
                           Select product).Single()

    ' Get the specific customer.
    Dim cust = (From customer In context.Customers.Expand("Orders") _
                Where customer.CustomerID = customerId _
                Select customer).Single()

    ' Get the first order. 
    Dim order = cust.Orders.FirstOrDefault()

    ' Create a new order detail for the specific product.
    newItem = Order_Detail.CreateOrder_Detail( _
            order.OrderID, selectedProduct.ProductID, 10, 5, 0)

    ' Add the new item with a link to the related order.
    context.AddRelatedObject(order, "Order_Details", newItem)
    
    ' Since the item is now tracked by the context,
    ' set just the link to the related product.
    context.AddLink(selectedProduct, "Order_Details", newItem)

    ' Add the new order detail to the collection, and
    ' set the reference to the product.
    order.Order_Details.Add(newItem)
    newItem.Order = order
    newItem.Product = selectedProduct

    ' Send the inserts to the data service.
    context.SaveChanges()
Catch ex As DataServiceQueryException
    Throw New ApplicationException( _
            "An error occurred when saving changes.", ex)

    ' Handle any errors that may occur during insert, such as 
    ' a constraint violation.
Catch ex As DataServiceRequestException
    Throw New ApplicationException( _
            "An error occurred when saving changes.", ex)

int productId = 25;
string customerId = "ALFKI";

Order_Detail newItem = null;

// Create the DataServiceContext using the service URI.
NorthwindEntities context = new NorthwindEntities(svcUri);

try
{
    // Get the specific product.
    var selectedProduct = (from product in context.Products
                           where product.ProductID == productId
                           select product).Single();

    // Get the specific customer.
    var cust = (from customer in context.Customers.Expand("Orders")
                where customer.CustomerID == customerId
                select customer).Single();

    // Get the first order. 
    Order order = cust.Orders.FirstOrDefault();

    // Create a new order detail for the specific product.
    newItem = Order_Detail.CreateOrder_Detail(
        order.OrderID, selectedProduct.ProductID, 10, 5, 0);

    // Add the new item with a link to the related order.
    context.AddRelatedObject(order, "Order_Details", newItem);
    
    // Since the item is now tracked by the context,
    // set just the link to the related product.
    context.AddLink(selectedProduct, "Order_Details", newItem);

    // Add the new order detail to the collection, and
    // set the reference to the product.
    order.Order_Details.Add(newItem);
    newItem.Order = order;
    newItem.Product = selectedProduct;
   
    // Send the inserts to the data service.
    context.SaveChanges();
}
catch (DataServiceQueryException ex)
{
    throw new ApplicationException(
        "An error occurred when saving changes.", ex);
}

// Handle any errors that may occur during insert, such as 
// a constraint violation.
catch (DataServiceRequestException ex)
{
    throw new ApplicationException(
        "An error occurred when saving changes.", ex);
}

参照

処理手順

方法: 既存のエンティティを DataServiceContext にアタッチする (WCF Data Services)
方法: エンティティ リレーションシップを定義する (WCF Data Services)

概念

バッチ処理 (WCF Data Services)

その他のリソース

WCF Data Services クライアント ライブラリ