ObjectDataSource.TypeName Proprietà

  • Riferimento

Definizione

Spazio dei nomi:
System.Web.UI.WebControls
Assembly:
System.Web.dll

Ottiene o imposta il nome della classe rappresentata dall'oggetto ObjectDataSource.

public:
 property System::String ^ TypeName { System::String ^ get(); void set(System::String ^ value); };
public string TypeName { get; set; }
member this.TypeName : string with get, set
Public Property TypeName As String

Valore della proprietà

String

Nome di classe parziale o completo che identifica il tipo di oggetto rappresentato dall'oggetto ObjectDataSource. Il valore predefinito è una stringa vuota ("").

Esempio

Nell'esempio di codice seguente viene illustrato come un controllo può visualizzare i dati usando un GridViewObjectDataSource controllo in una pagina Web Forms. Identifica ObjectDataSource un nome di classe parzialmente o completo con la relativa TypeName proprietà e un metodo chiamato per recuperare i dati con la relativa SelectMethod proprietà. In fase di esecuzione, l'oggetto viene creato e il metodo viene chiamato usando reflection. Il GridView controllo enumera la IEnumerable raccolta restituita dalla SelectMethod proprietà e visualizza i dati.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS" Assembly="Samples.AspNet.CS" %>
<%@ Page language="c#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>ObjectDataSource - C# Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <asp:gridview
          id="GridView1"
          runat="server"
          datasourceid="ObjectDataSource1" />

        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployees"
          typename="Samples.AspNet.CS.EmployeeLogic" />

    </form>
  </body>
</html>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB" Assembly="Samples.AspNet.VB" %>
<%@ Page language="vb" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>ObjectDataSource - Visual Basic Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <asp:gridview
          id="GridView1"
          runat="server"
          datasourceid="ObjectDataSource1" />

        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployees"
          typename="Samples.AspNet.VB.EmployeeLogic" />

    </form>
  </body>
</html>

Nell'esempio seguente viene illustrata la classe a cui fa riferimento il valore della TypeName proprietà.

namespace Samples.AspNet.CS {

using System;
using System.Collections;
using System.Collections.Specialized;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Web.UI;
using System.Web.UI.WebControls;
  //
  // EmployeeLogic is a stateless business object that encapsulates
  // the operations one can perform on a NorthwindEmployee object.
  //
  public class EmployeeLogic {

    // Returns a collection of NorthwindEmployee objects.
    public static ICollection GetAllEmployees () {
      ArrayList al = new ArrayList();

      ConnectionStringSettings cts = ConfigurationManager.ConnectionStrings["NorthwindConnection"];

      SqlDataSource sds
        = new SqlDataSource(cts.ConnectionString, "SELECT EmployeeID FROM Employees");

      try {

        IEnumerable IDs = sds.Select(DataSourceSelectArguments.Empty);

        // Iterate through the Enumeration and create a
        // NorthwindEmployee object for each ID.
        foreach (DataRowView row in IDs) {
          string id = row["EmployeeID"].ToString();
          NorthwindEmployee nwe = new NorthwindEmployee(id);
          // Add the NorthwindEmployee object to the collection.
          al.Add(nwe);
        }
      }
      finally {
        // If anything strange happens, clean up.
        sds.Dispose();
      }

      return al;
    }
    public static NorthwindEmployee GetEmployee(object anID) {
      return new NorthwindEmployee(anID);
    }

    public static void UpdateEmployeeInfo(NorthwindEmployee ne) {
      bool retval = ne.Save();
      if (! retval) { throw new NorthwindDataException("UpdateEmployee failed."); }
    }

    public static void DeleteEmployee(NorthwindEmployee ne) { }
  }

  public class NorthwindEmployee {

    public NorthwindEmployee () {
      ID = DBNull.Value;
      lastName = "";
      firstName = "";
      title="";
      titleOfCourtesy = "";
      reportsTo = -1;
    }

    public NorthwindEmployee (object anID) {
      this.ID = anID;

      ConnectionStringSettings cts = ConfigurationManager.ConnectionStrings["NorthwindConnection"];

        SqlConnection conn = new SqlConnection (cts.ConnectionString);
      SqlCommand sc =
        new SqlCommand(" SELECT FirstName,LastName,Title,TitleOfCourtesy,ReportsTo " +
                       " FROM Employees " +
                       " WHERE EmployeeID = @empId",
                       conn);
      // Add the employee ID parameter and set its value.
      sc.Parameters.Add(new SqlParameter("@empId",SqlDbType.Int)).Value = Int32.Parse(anID.ToString());
      SqlDataReader sdr = null;

      try {
        conn.Open();
        sdr = sc.ExecuteReader();

        // This is not a while loop. It only loops once.
        if (sdr != null && sdr.Read()) {
          // The IEnumerable contains DataRowView objects.
          this.firstName        = sdr["FirstName"].ToString();
          this.lastName         = sdr["LastName"].ToString();
          this.title            = sdr["Title"].ToString();
          this.titleOfCourtesy  = sdr["TitleOfCourtesy"].ToString();
          if (! sdr.IsDBNull(4)) {
            this.reportsTo        = sdr.GetInt32(4);
          }
        }
        else {
          throw new NorthwindDataException("Data not loaded for employee id.");
        }
      }
      finally {
        try {
          if (sdr != null) sdr.Close();
          conn.Close();
        }
        catch (SqlException) {
          // Log an event in the Application Event Log.
          throw;
        }
      }
    }

    private object ID;

    private string lastName;
    public string LastName {
      get { return lastName; }
      set { lastName = value; }
    }

    private string firstName;
    public string FirstName {
      get { return firstName; }
      set { firstName = value;  }
    }

    private string title;
    public String Title {
      get { return title; }
      set { title = value; }
    }

    private string titleOfCourtesy;
    public string Courtesy {
      get { return titleOfCourtesy; }
      set { titleOfCourtesy = value; }
    }

    private int    reportsTo;
    public int Supervisor {
      get { return reportsTo; }
      set { reportsTo = value; }
    }

    public bool Save () {
      return true;
    }
  }

  internal class NorthwindDataException: Exception {
    public NorthwindDataException(string msg) : base (msg) { }
  }
}

Imports System.Collections
Imports System.Configuration
Imports System.Data
Imports System.Data.SqlClient
Imports System.Web.UI
Imports System.Web.UI.WebControls

Namespace Samples.AspNet.VB
'
' EmployeeLogic is a stateless business object that encapsulates
' the operations you can perform on a NorthwindEmployee object.
' When the class is written in Visual Basic, you cannot use the Shared
' part.
Public Class EmployeeLogic
   ' Returns a collection of NorthwindEmployee objects.
   Public Shared Function GetAllEmployees() As ICollection
      Dim al As New ArrayList()

      Dim cts As ConnectionStringSettings = ConfigurationManager.ConnectionStrings("NorthwindConnection")
      Dim sds As New SqlDataSource(cts.ConnectionString, "SELECT EmployeeID FROM Employees")
      Try
         Dim IDs As IEnumerable = sds.Select(DataSourceSelectArguments.Empty)

         ' Iterate through the Enumeration and create a
         ' NorthwindEmployee object for each ID.
         For Each row As DataRowView In IDs
            Dim id As String = row("EmployeeID").ToString()
            Dim nwe As New NorthwindEmployee(id)
            ' Add the NorthwindEmployee object to the collection.
            al.Add(nwe)
         Next
      Finally
         ' If anything strange happens, clean up.
         sds.Dispose()
      End Try

      Return al
   End Function 'GetAllEmployees

   Public Shared Function GetEmployee(anID As Object) As NorthwindEmployee
      Return New NorthwindEmployee(anID)
   End Function 'GetEmployee


   Public Shared Sub UpdateEmployeeInfo(ne As NorthwindEmployee)
      Dim retval As Boolean = ne.Save()
      If Not retval Then
         Throw New NorthwindDataException("UpdateEmployee failed.")
      End If
   End Sub

   Public Shared Sub DeleteEmployee(ne As NorthwindEmployee)
   End Sub

End Class


Public Class NorthwindEmployee


   Public Sub New()
      ID = DBNull.Value
      aLastName = ""
      aFirstName = ""
      aTitle = ""
      titleOfCourtesy = ""
      reportsTo = - 1
   End Sub


   Public Sub New(anID As Object)
      Me.ID = anID
      Dim cts As ConnectionStringSettings = ConfigurationManager.ConnectionStrings("NorthwindConnection")
      Dim conn As New SqlConnection(cts.ConnectionString)
      Dim sc As New SqlCommand(" SELECT FirstName,LastName,Title,TitleOfCourtesy,ReportsTo " & _
                               " FROM Employees " & _
                               " WHERE EmployeeID = @empId", conn)
      ' Add the employee ID parameter and set its value.
      sc.Parameters.Add(New SqlParameter("@empId", SqlDbType.Int)).Value = Int32.Parse(anID.ToString())
      Dim sdr As SqlDataReader = Nothing

      Try
         conn.Open()
         sdr = sc.ExecuteReader()

         ' This is not a while loop. It only loops once.
         If Not (sdr Is Nothing) AndAlso sdr.Read() Then
            ' The IEnumerable contains DataRowView objects.
            Me.aFirstName = sdr("FirstName").ToString()
            Me.aLastName = sdr("LastName").ToString()
            Me.aTitle = sdr("Title").ToString()
            Me.titleOfCourtesy = sdr("TitleOfCourtesy").ToString()
            If Not sdr.IsDBNull(4) Then
               Me.reportsTo = sdr.GetInt32(4)
            End If
         Else
            Throw New NorthwindDataException("Data not loaded for employee id.")
         End If
      Finally
         Try
            If Not (sdr Is Nothing) Then
               sdr.Close()
            End If
            conn.Close()
         Catch se As SqlException
            ' Log an event in the Application Event Log.
            Throw
         End Try
      End Try
   End Sub

   Private ID As Object

   Private aLastName As String
   Public Property LastName() As String
      Get
         Return aLastName
      End Get
      Set
         aLastName = value
      End Set
   End Property

   Private aFirstName As String
   Public Property FirstName() As String
      Get
         Return aFirstName
      End Get
      Set
         aFirstName = value
      End Set
   End Property

   Private aTitle As String
   Public Property Title() As String
      Get
         Return aTitle
      End Get
      Set
         aTitle = value
      End Set
   End Property

   Private titleOfCourtesy As String
   Public Property Courtesy() As String
      Get
         Return titleOfCourtesy
      End Get
      Set
         titleOfCourtesy = value
      End Set
   End Property
   Private reportsTo As Integer

   Public Property Supervisor() As Integer
      Get
         Return reportsTo
      End Get
      Set
         reportsTo = value
      End Set
   End Property

   Public Function Save() As Boolean
      Return True
   End Function 'Save
End Class


Friend Class NorthwindDataException
   Inherits Exception

   Public Sub New(msg As String)
      MyBase.New(msg)
   End Sub
End Class
End Namespace

Commenti

Per creare un'istanza dell'oggetto a cui viene associato il controllo, il ObjectDataSource controllo usa la reflection per caricare il tipo identificato dal nome del tipo in fase di esecuzione. Pertanto, il valore della TypeName proprietà può essere un tipo parzialmente qualificato per il codice che si trova nel bin o App_Code directory o un nome di tipo completo per il codice registrato nella global assembly cache. Se si usa la global assembly cache, è necessario aggiungere il riferimento appropriato alla assemblies sezione del file Machine.config o Web.config.

Il tipo deve avere un costruttore senza parametri, a meno che non si gestisca l'evento per crearne un'istanza ObjectCreating . Viene creata un'istanza del tipo per ogni chiamata ai Selectmetodi , , InsertUpdateeDelete, se i metodi nel tipo sono metodi membro. Un'istanza non viene creata se i metodi sono static (Shared in Visual Basic). Se il tipo implementa l'interfaccia, il Dispose metodo viene chiamato prima che l'oggetto IDisposable venga distrutto.

Si applica a

Vedi anche