Cómo crear un objeto con el método de creación estático (Entity Framework)
Las herramientas de Entity Framework usan un archivo del lenguaje de definición de esquemas conceptuales (CSDL) para generar el código que define el nivel de objetos. Cuando se generan las clases de datos, cada clase se genera con un método de fábrica create. Este método se usa para crear una instancia de un objeto y establecer las propiedades de la clase que no pueden ser Null. El método incluye un parámetro de cada propiedad que tiene aplicado el atributo Nullable="false" en el archivo de CSDL. Use este método al crear objetos con muchas propiedades requeridas.
Los ejemplos de este tema se basan en el modelo AdventureWorks Sales. Para ejecutar el código de este ejemplo, debe haber agregado ya el modelo de ventas de AdventureWorks al proyecto y haber configurado el proyecto para usar Entity Framework. Para ello, complete los procedimientos de Cómo configurar manualmente un proyecto de Entity Framework y Cómo definir manualmente un modelo Entity Data Model (Entity Framework).
Ejemplo
El ejemplo siguiente es un fragmento de CSDL para el tipo SalesOrderHeader del Modelo AdventureWorks Sales (EDM):
<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>
El ejemplo siguiente muestra el método CreateSalesOrderHeader estático generado para la clase SalesOrderHeader en AdventureWorks:
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;
}
El ejemplo siguiente muestra cómo usar el método CreateSalesOrderHeader estático para crear y guardar un objeto SalesOrderHeader:
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());
}
}
Vea también
Conceptos
Agregar, modificar y eliminar objetos (Entity Framework)
Información general de Servicios de objeto (Entity Framework)