Anpassa åtgärder med hjälp av lagrade procedurer
Lagrade procedurer representerar en vanlig metod för att åsidosätta standardbeteende. Exemplen i det här avsnittet visar hur du kan använda genererade metodomslutningar för lagrade procedurer och hur du kan anropa lagrade procedurer direkt.
Om du använder Visual Studio kan du använda Objektrelationsdesignern för att tilldela lagrade procedurer för att utföra infogningar, uppdateringar och borttagningar.
Kommentar
Om du vill läsa tillbaka databasgenererade värden använder du utdataparametrar i dina lagrade procedurer. Om du inte kan använda utdataparametrar skriver du en partiell metodimplementering i stället för att förlita dig på åsidosättningar som genereras av objektrelationsdesignern. Medlemmar som mappas till databasgenererade värden måste anges till lämpliga värden efter INSERT att åtgärderna UPDATE har slutförts. Mer information finns i Ansvarsområden för utvecklaren i övergripande standardbeteende.
Exempel 1
Anta i följande exempel att Northwind klassen innehåller två metoder för att anropa lagrade procedurer som används för åsidosättningar i en härledd klass.
[Function()]
public IEnumerable<Order> CustomerOrders(
[Parameter(Name = "CustomerID", DbType = "NChar(5)")]
string customerID)
{
IExecuteResult result = this.ExecuteMethodCall(this,
((MethodInfo)(MethodInfo.GetCurrentMethod())),
customerID);
return ((IEnumerable<Order>)(result.ReturnValue));
}
[Function()]
public IEnumerable<Customer> CustomerById(
[Parameter(Name = "CustomerID", DbType = "NChar(5)")]
string customerID)
{
IExecuteResult result = this.ExecuteMethodCall(this,
((MethodInfo)(MethodInfo.GetCurrentMethod())),
customerID);
return (IEnumerable<Customer>)(result.ReturnValue);
}
<[Function]()> _
Public Function CustomerOrders( _
<Parameter(Name:="CustomerID", DbType:="NChar(5)")> ByVal _
customerID As String) As IEnumerable(Of Order)
Dim result As IExecuteResult = Me.ExecuteMethodCall(Me, _
(CType(MethodInfo.GetCurrentMethod(), MethodInfo)), _
customerID)
Return CType(result.ReturnValue, IEnumerable(Of Order))
End Function
<[Function]()> _
Public Function CustomerById( _
<Parameter(Name:="CustomerID", DbType:="NChar(5)")> ByVal _
customerID As String) As IEnumerable(Of Customer)
Dim result As IExecuteResult = Me.ExecuteMethodCall(Me, _
CType(MethodInfo.GetCurrentMethod(), MethodInfo), _
customerID)
Return CType(result.ReturnValue, IEnumerable(Of Customer))
End Function
Exempel 2
Följande klass använder dessa metoder för åsidosättningen.
public class NorthwindThroughSprocs : Northwind
{
public NorthwindThroughSprocs(string connection) :
base(connection)
{
}
// Override loading of Customer.Orders by using method wrapper.
private IEnumerable<Order> LoadOrders(Customer customer)
{
return this.CustomerOrders(customer.CustomerID);
}
// Override loading of Order.Customer by using method wrapper.
private Customer LoadCustomer(Order order)
{
return this.CustomerById(order.CustomerID).Single();
}
// Override INSERT operation on Customer by calling the
// stored procedure directly.
private void InsertCustomer(Customer customer)
{
// Call the INSERT stored procedure directly.
this.ExecuteCommand("exec sp_insert_customer …");
}
// The UPDATE override works similarly, that is, by
// calling the stored procedure directly.
private void UpdateCustomer(Customer original, Customer current)
{
// Call the UPDATE stored procedure by using current
// and original values.
this.ExecuteCommand("exec sp_update_customer …");
}
// The DELETE override works similarly.
private void DeleteCustomer(Customer customer)
{
// Call the DELETE stored procedure directly.
this.ExecuteCommand("exec sp_delete_customer …");
}
}
Public Class NorthwindThroughSprocs : Inherits Northwind
Sub New()
MyBase.New("")
End Sub
' Override loading of Customer.Orders by using method wrapper.
Private Function LoadOrders(ByVal customer As Customer) As _
IEnumerable(Of Order)
Return Me.CustomerOrders(customer.CustomerID)
End Function
' Override loading of Order.Customer by using method wrapper.
Private Function LoadCustomer(ByVal order As Order) As Customer
Return Me.CustomerById(order.CustomerID).Single()
End Function
' Override INSERT operation on Customer by calling the
' stored procedure directly.
Private Sub InsertCustomer(ByVal customer As Customer)
' Call the INSERT stored procedure directly.
Me.ExecuteCommand("exec sp_insert_customer …")
End Sub
' The UPDATE override works similarly, that is, by
' calling the stored procedure directly.
Private Sub UpdateCustomer(ByVal original As Customer, ByVal _
current As Customer)
' Call the UPDATE stored procedure by using current
' and original values.
Me.ExecuteCommand("exec sp_update_customer …")
End Sub
' The DELETE override works similarly.
Private Sub DeleteCustomer(ByVal customer As Customer)
' Call the DELETE stored procedure directly.
Me.ExecuteCommand("exec sp_delete_customer …")
End Sub
End Class
Exempel 3
Du kan använda NorthwindThroughSprocs exakt som du skulle använda Northwnd.
NorthwindThroughSprocs db = new NorthwindThroughSprocs("");
var custQuery =
from cust in db.Customers
where cust.City == "London"
select cust;
foreach (Customer custObj in custQuery)
// deferred loading of cust.Orders uses the override LoadOrders.
foreach (Order ord in custObj.Orders)
// ...
// Make some changes to customers/orders.
// Overrides for Customer are called during the execution of the
// following:
db.SubmitChanges();
Dim db As New NorthwindThroughSprocs()
Dim custQuery = From cust In db.Customers _
Where cust.City = "London" _
Select cust
For Each custObj In custQuery
' Deferred loading of cust.Orders uses the override LoadOrders.
For Each ord In custObj.Orders
' ...
' Make some changes to customers/orders.
' Overrides for Customer are called during the execution
' of the following:
db.SubmitChanges()
Next
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