Menyesuaikan Operasi Dengan Menggunakan Prosedur Tersimpan
Prosedur tersimpan mewakili pendekatan umum untuk menggantikan perilaku default. Contoh dalam topik ini menunjukkan cara Anda dapat menggunakan pembungkus metode yang dihasilkan untuk prosedur tersimpan, dan cara Anda dapat memanggil prosedur tersimpan secara langsung.
Jika Anda menggunakan Visual Studio, Anda dapat menggunakan Perancang Relasional Objek untuk menetapkan prosedur tersimpan guna melakukan penyisipan, pembaruan, dan penghapusan.
Catatan
Untuk membaca kembali nilai yang dihasilkan database, gunakan parameter output dalam prosedur tersimpan Anda. Jika Anda tidak dapat menggunakan parameter output, tulis penerapan metode parsial, bukan mengandalkan penggantian yang dihasilkan oleh Perancang Relasional Objek. Anggota yang dipetakan ke nilai yang dihasilkan database harus diatur ke nilai yang sesuai setelah operasi INSERT atau UPDATE berhasil diselesaikan. Untuk informasi selengkapnya, baca Tanggung Jawab Pengembang Dalam Mengambil alih Perilaku Default.
Contoh 1
Dalam contoh berikut, asumsikan bahwa kelas Northwind berisi dua metode untuk memanggil prosedur tersimpan yang digunakan untuk penggantian di kelas turunan.
[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
Contoh 2
Kelas berikut menggunakan metode ini untuk penggantian.
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
Contoh 3
Anda dapat menggunakan NorthwindThroughSprocs persis seperti saat Anda menggunakan 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()
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