HOW TO：使用靜態 Create 方法建立物件 (Entity Framework)
實體架構 工具會使用概念結構定義語言 (CSDL) 檔案來產生定義物件層的程式碼。 當產生資料類別時，每一個類別都是使用靜態 create factory 方法所產生。 此方法是用來具現化物件，並設定不能為 null 之類別的所有屬性。 此方法會針對具有 CSDL 檔案中套用之 Nullable="false" 屬性 (Attribute) 的每一個屬性 (Property) 各包括一個參數。 當使用許多必要屬性建立物件時，請使用這個方法。
本主題的範例是根據 Adventure Works Sales Model。 若要執行此範例中的程式碼，您必須已經將 AdventureWorks Sales Model 加入到專案中，並設定您的專案使用 Entity Framework。 若要這樣做，請完成 HOW TO：手動設定 Entity Framework 專案和 HOW TO：以手動方式定義 Entity Data Model (Entity Framework) 中的程序。
範例
下列是 AdventureWorks Sales Model (EDM) 中 SalesOrderHeader 型別的範例 CSDL 片段：
<EntityType Name="SalesOrderHeader">
<Key>
<PropertyRef Name="SalesOrderID" />
</Key>
<Property Name="SalesOrderID" Type="Int32" Nullable="false" />
<Property Name="RevisionNumber" Type="Byte" Nullable="false" />
<Property Name="OrderDate" Type="DateTime" Nullable="false" />
<Property Name="DueDate" Type="DateTime" Nullable="false" />
<Property Name="ShipDate" Type="DateTime" />
<Property Name="Status" Type="Byte" Nullable="false" ConcurrencyMode="Fixed" />
<Property Name="OnlineOrderFlag" Type="Boolean" Nullable="false" />
<Property Name="SalesOrderNumber" Type="String" Nullable="false" MaxLength="25" Unicode="true" FixedLength="false" />
<Property Name="PurchaseOrderNumber" Type="String" MaxLength="25" Unicode="true" FixedLength="false" />
<Property Name="AccountNumber" Type="String" MaxLength="15" Unicode="true" FixedLength="false" />
<Property Name="CustomerID" Type="Int32" Nullable="false" />
<Property Name="SalesPersonID" Type="Int32" />
<Property Name="TerritoryID" Type="Int32" />
<Property Name="ShipMethodID" Type="Int32" Nullable="false" />
<Property Name="CreditCardID" Type="Int32" />
<Property Name="CreditCardApprovalCode" Type="String" MaxLength="15" Unicode="false" FixedLength="false" />
<Property Name="CurrencyRateID" Type="Int32" />
<Property Name="SubTotal" Type="Decimal" Nullable="false" Precision="19" Scale="4" />
<Property Name="TaxAmt" Type="Decimal" Nullable="false" Precision="19" Scale="4" />
<Property Name="Freight" Type="Decimal" Nullable="false" Precision="19" Scale="4" />
<Property Name="TotalDue" Type="Decimal" Nullable="false" Precision="19" Scale="4" />
<Property Name="Comment" Type="String" MaxLength="128" Unicode="true" FixedLength="false" />
<Property Name="rowguid" Type="Guid" Nullable="false" />
<Property Name="ModifiedDate" Type="DateTime" Nullable="false" />
<NavigationProperty Name="Address" Relationship="AdventureWorksModel.FK_SalesOrderHeader_Address_BillToAddressID" FromRole="SalesOrderHeader" ToRole="Address" />
<NavigationProperty Name="Address1" Relationship="AdventureWorksModel.FK_SalesOrderHeader_Address_ShipToAddressID" FromRole="SalesOrderHeader" ToRole="Address" />
<NavigationProperty Name="Contact" Relationship="AdventureWorksModel.FK_SalesOrderHeader_Contact_ContactID" FromRole="SalesOrderHeader" ToRole="Contact" />
<NavigationProperty Name="SalesOrderDetail" Relationship="AdventureWorksModel.FK_SalesOrderDetail_SalesOrderHeader_SalesOrderID" FromRole="SalesOrderHeader" ToRole="SalesOrderDetail" />
</EntityType>
下列是 AdventureWorks 中針對 SalesOrderHeader 類別產生之靜態 CreateSalesOrderHeader 方法的範例：
Public Shared Function CreateSalesOrderHeader(ByVal salesOrderID As Integer, _
ByVal revisionNumber As Byte, ByVal orderDate As Date, ByVal dueDate As Date, _
ByVal status As Byte, ByVal onlineOrderFlag As Boolean, _
ByVal salesOrderNumber As String, ByVal customerID As Integer, _
ByVal shipMethodID As Integer, ByVal subTotal As Decimal, ByVal taxAmt As Decimal, _
ByVal freight As Decimal, ByVal totalDue As Decimal, ByVal rowguid As Global.System.Guid, _
ByVal modifiedDate As Date) As SalesOrderHeader
Dim salesOrderHeader As SalesOrderHeader = New SalesOrderHeader
salesOrderHeader.SalesOrderID = salesOrderID
salesOrderHeader.RevisionNumber = revisionNumber
salesOrderHeader.OrderDate = orderDate
salesOrderHeader.DueDate = dueDate
salesOrderHeader.Status = status
salesOrderHeader.OnlineOrderFlag = onlineOrderFlag
salesOrderHeader.SalesOrderNumber = salesOrderNumber
salesOrderHeader.CustomerID = customerID
salesOrderHeader.ShipMethodID = shipMethodID
salesOrderHeader.SubTotal = subTotal
salesOrderHeader.TaxAmt = taxAmt
salesOrderHeader.Freight = freight
salesOrderHeader.TotalDue = totalDue
salesOrderHeader.rowguid = rowguid
salesOrderHeader.ModifiedDate = modifiedDate
Return salesOrderHeader
End Function
public static SalesOrderHeader CreateSalesOrderHeader(int salesOrderID,
byte revisionNumber, global::System.DateTime orderDate,
global::System.DateTime dueDate, byte status, bool onlineOrderFlag,
string salesOrderNumber, int customerID, int shipMethodID, decimal subTotal,
decimal taxAmt, decimal freight, decimal totalDue, global::System.Guid rowguid,
global::System.DateTime modifiedDate)
{
SalesOrderHeader salesOrderHeader = new SalesOrderHeader();
salesOrderHeader.SalesOrderID = salesOrderID;
salesOrderHeader.RevisionNumber = revisionNumber;
salesOrderHeader.OrderDate = orderDate;
salesOrderHeader.DueDate = dueDate;
salesOrderHeader.Status = status;
salesOrderHeader.OnlineOrderFlag = onlineOrderFlag;
salesOrderHeader.SalesOrderNumber = salesOrderNumber;
salesOrderHeader.CustomerID = customerID;
salesOrderHeader.ShipMethodID = shipMethodID;
salesOrderHeader.SubTotal = subTotal;
salesOrderHeader.TaxAmt = taxAmt;
salesOrderHeader.Freight = freight;
salesOrderHeader.TotalDue = totalDue;
salesOrderHeader.rowguid = rowguid;
salesOrderHeader.ModifiedDate = modifiedDate;
return salesOrderHeader;
}
下列範例將示範如何使用靜態 CreateSalesOrderHeader 方法來建立及儲存 SalesOrderHeader 物件：
Dim productId As Integer = 777 'Mountain-100 Black, 44
Dim quantity As Short = 1
Dim lastName As String = "Adams"
Dim firstName As String = "Frances"
Dim invoiceNumber As String = "PO123456"
Dim shipMethod As Integer = 5
Dim specialOffer As Integer = 1
Using advWorksContext As New AdventureWorksEntities()
Try
' Get the Contact for the specific customer
' and the related address.
Dim customer As Contact = advWorksContext.Contact _
.Include("SalesOrderHeader.Address") _
.Where("it.LastName = @lastname", _
New ObjectParameter("lastname", lastName)) _
.Where("it.FirstName = @firstname", _
New ObjectParameter("firstname", firstName)) _
.First()
' Get the customer's address to use to create
' a new order with the same address.
Dim address As Address = customer.SalesOrderHeader _
.First().Address()
' Get the Product with the requested ID.
Dim product As Product = _
advWorksContext.Product.Where("it.ProductID = @product_id", _
New ObjectParameter("product_id", productId)).First()
' Create a new SalesOrderHeader using the static
' CreateSalesOrderHeader method.
Dim order As SalesOrderHeader = _
SalesOrderHeader.CreateSalesOrderHeader( _
1, Convert.ToByte(1), DateTime.Now, DateTime.Today.AddMonths(2), _
Convert.ToByte(1), False, String.Empty, customer.ContactID, shipMethod, _
0, 0, 0, 0, Guid.NewGuid(), DateTime.Now)
' Set addition order properties.
order.Address = address
order.Address1 = address
order.PurchaseOrderNumber = invoiceNumber
' Create a new SalesOrderDetail using the static
' CreateSalesOrderDetail method.
Dim item As SalesOrderDetail = _
SalesOrderDetail.CreateSalesOrderDetail( _
1, 0, quantity, product.ProductID, specialOffer, product.StandardCost, _
0, 0, Guid.NewGuid(), DateTime.Now)
' Add item to the items collection and
' add order to the orders collection.
order.SalesOrderDetail.Add(item)
customer.SalesOrderHeader.Add(order)
' Call a custom method to recalculate totals.
' For more information, see "Customizing Objects."
order.UpdateOrderTotal()
' Save changes pessimistically. This means that changes
' must be accepted manually once the transaction succeeds.
advWorksContext.SaveChanges()
Console.WriteLine("Order created with order number: " _
+ order.SalesOrderNumber)
Catch ex As Exception
Console.WriteLine(ex.ToString())
End Try
End Using
int productId = 777; //Mountain-100 Black, 44
short quantity = 1;
string lastName = @"Adams";
string firstName = @"Frances";
string invoiceNumber = "PO123456";
int shipMethod = 5;
int specialOffer = 1;
using (AdventureWorksEntities advWorksContext =
new AdventureWorksEntities())
{
try
{
// Get the Contact for the specific customer
// and the related address.
Contact customer = advWorksContext.Contact
.Include("SalesOrderHeader.Address")
.Where("it.LastName = @lastname",
new ObjectParameter("lastname", lastName))
.Where("it.FirstName = @firstname",
new ObjectParameter("firstname", firstName))
.First();
// Get the customer's address to use to create
// a new order with the same address.
Address address = customer.SalesOrderHeader
.First().Address;
// Get the Product with the requested ID.
Product product =
advWorksContext.Product.Where("it.ProductID = @product_id",
new ObjectParameter("product_id", productId)).First();
// Create a new SalesOrderHeader using the static
// CreateSalesOrderHeader method.
SalesOrderHeader order = SalesOrderHeader.CreateSalesOrderHeader(0,
Convert.ToByte(1), DateTime.Now, DateTime.Today.AddMonths(2),
Convert.ToByte(1), false, string.Empty, customer.ContactID, shipMethod,
0, 0, 0, 0, Guid.NewGuid(), DateTime.Now);
// Set addition order properties.
order.Address = address;
order.Address1 = address;
order.PurchaseOrderNumber = invoiceNumber;
// Create a new SalesOrderDetail using the static
// CreateSalesOrderDetail method.
SalesOrderDetail item = SalesOrderDetail.CreateSalesOrderDetail(
1, 0, quantity, product.ProductID, specialOffer, product.StandardCost,
0, 0,Guid.NewGuid(), DateTime.Now);
// Add item to the items collection and
// add order to the orders collection.
order.SalesOrderDetail.Add(item);
customer.SalesOrderHeader.Add(order);
// Call a custom method to recalculate totals.
// For more information, see "Customizing Objects."
order.UpdateOrderTotal();
// Save changes pessimistically. This means that changes
// must be accepted manually once the transaction succeeds.
advWorksContext.SaveChanges();
Console.WriteLine("Order created with order number: "
+ order.SalesOrderNumber);
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
}