Modifica

GridViewDeletedEventArgs.Keys Property

  • Reference

Definition

Namespace:
System.Web.UI.WebControls
Assembly:
System.Web.dll

Gets an ordered dictionary of key field name/value pairs for the deleted record.

public:
 property System::Collections::Specialized::IOrderedDictionary ^ Keys { System::Collections::Specialized::IOrderedDictionary ^ get(); };
public System.Collections.Specialized.IOrderedDictionary Keys { get; }
member this.Keys : System.Collections.Specialized.IOrderedDictionary
Public ReadOnly Property Keys As IOrderedDictionary

Property Value

IOrderedDictionary

A IOrderedDictionary that contains an ordered dictionary of key field name/value pairs for the deleted record.

Examples

The following example demonstrates how to use the Keys property to access the values of the key fields for a deleted record.


<%@ Page language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  void CustomersGridView_RowDeleted(Object sender, GridViewDeletedEventArgs e)
  {
    // Display the value of the key fields in the Keys property.
    KeysMessageLabel.Text =
      "The key fields for the deleted record are: <br/>";

    foreach (DictionaryEntry entry in e.Keys)
    {
      DisplayValue(entry, KeysMessageLabel);
    }

    // Display the value of the non-key fields in the Values 
    // property.
    ValuesMessageLabel.Text =
      "The non-key fields for the deleted record are: <br/>";

    foreach (DictionaryEntry entry in e.Values)
    {
      DisplayValue(entry, ValuesMessageLabel);
    }

  }

  void DisplayValue(DictionaryEntry entry, Label displayLabel)
  {
    // Display the field name contained in the DictionaryEntry object.
    if (entry.Key != null)
    {
      displayLabel.Text += "Name=" + entry.Key.ToString() + ", ";
    }
    else
    {
      displayLabel.Text += "Name=null, ";
    }

    // Display the field value contained in the DictionaryEntry object.
    if (entry.Value != null)
    {
      displayLabel.Text += "Value=" + entry.Value.ToString() + "<br/>";
    }
    else
    {
      displayLabel.Text += "Value=null<br/>";
    }
  }
    
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridViewDeletedEventArgs Keys and Values Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridViewDeletedEventArgs Keys and Values Example</h3>
            
      <asp:label id="Message"
        forecolor="Red"          
        runat="server"/>
                
      <br/>
            
      <!-- The GridView control automatically sets the columns     -->
      <!-- specified in the datakeynames property as read-only.    -->
      <!-- No input controls are rendered for these columns in     -->
      <!-- edit mode.                                              -->
      <asp:gridview id="CustomersGridView" 
        datasourceid="CustomersSqlDataSource" 
        autogeneratecolumns="true"
        autogeneratedeletebutton="true"
        allowpaging="true" 
        datakeynames="CustomerID"
        onrowdeleted="CustomersGridView_RowDeleted"  
        runat="server">
      </asp:gridview>
      
      <br/>
      
      <asp:label id="KeysMessageLabel"
        forecolor="Red"
        runat="server"/>
          
      <br/><br/>
          
      <asp:label id="ValuesMessageLabel"
        forecolor="Red"
        runat="server"/>
            
      <!-- This example uses Microsoft SQL Server and connects  -->
      <!-- to the Northwind sample database. Use an ASP.NET     -->
      <!-- expression to retrieve the connection string value   -->
      <!-- from the Web.config file.                            -->
      <asp:sqldatasource id="CustomersSqlDataSource"  
        selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
        deletecommand="Delete from Customers where CustomerID = @CustomerID"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
        runat="server">
      </asp:sqldatasource>
      
    </form>
  </body>
</html>


<%@ Page language="VB" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

  Sub CustomersGridView_RowDeleted(ByVal sender As Object, ByVal e As GridViewDeletedEventArgs)
  
    Dim entry As DictionaryEntry
    
    ' Display the value of the key fields in the Keys property.
    KeysMessageLabel.Text = _
      "The key fields for the deleted record are: <br/>"

    ' In VB, you cannot iterate through the DictionaryEntry objects
    ' in the Keys property directly. Use the CopyTo method to 
    ' copy the objects to an array first.
    Dim keysArray(e.Keys.Count - 1) As DictionaryEntry
    e.Keys.CopyTo(keysArray, 0)
    
    ' Iterate through the array and display its values.
    For Each entry In keysArray
    
      DisplayValue(entry, KeysMessageLabel)
    
    Next

    ' Display the value of the non-key fields in the Values 
    ' property.
    ValuesMessageLabel.Text = _
      "The non-key fields for the deleted record are: <br/>"

    Dim valuesArray(e.Values.Count - 1) As DictionaryEntry
    e.Values.CopyTo(valuesArray, 0)

    For Each entry In valuesArray
    
      DisplayValue(entry, ValuesMessageLabel)
    
    Next

  End Sub

  Sub DisplayValue(ByVal entry As DictionaryEntry, ByVal displayLabel As Label)
  
    ' Display the field name contained in the DictionaryEntry object.
    If entry.Key IsNot Nothing Then
    
      displayLabel.Text &= "Name=" & entry.Key.ToString() & ", "
    
    Else
    
      displayLabel.Text &= "Name=null, "
      
    End If

    ' Display the field value contained in the DictionaryEntry object.
    If entry.Value IsNot Nothing Then
    
      displayLabel.Text &= "Value=" & entry.Value.ToString() & "<br/>"
    
    Else
    
      displayLabel.Text &= "Value=null<br/>"
      
    End If
        
  End Sub
    
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>GridViewDeletedEventArgs Keys and Values Example</title>
</head>
<body>
    <form id="form1" runat="server">
        
      <h3>GridViewDeletedEventArgs Keys and Values Example</h3>
            
      <asp:label id="Message"
        forecolor="Red"          
        runat="server"/>
                
      <br/>
            
      <!-- The GridView control automatically sets the columns     -->
      <!-- specified in the datakeynames property as read-only.    -->
      <!-- No input controls are rendered for these columns in     -->
      <!-- edit mode.                                              -->
      <asp:gridview id="CustomersGridView" 
        datasourceid="CustomersSqlDataSource" 
        autogeneratecolumns="true"
        autogeneratedeletebutton="true"
        allowpaging="true" 
        datakeynames="CustomerID"
        onrowdeleted="CustomersGridView_RowDeleted"  
        runat="server">
      </asp:gridview>
      
      <br/>
      
      <asp:label id="KeysMessageLabel"
        forecolor="Red"
        runat="server"/>
          
      <br/><br/>
          
      <asp:label id="ValuesMessageLabel"
        forecolor="Red"
        runat="server"/>
            
      <!-- This example uses Microsoft SQL Server and connects  -->
      <!-- to the Northwind sample database. Use an ASP.NET     -->
      <!-- expression to retrieve the connection string value   -->
      <!-- from the Web.config file.                            -->
      <asp:sqldatasource id="CustomersSqlDataSource"  
        selectcommand="Select [CustomerID], [CompanyName], [Address], [City], [PostalCode], [Country] From [Customers]"
        deletecommand="Delete from Customers where CustomerID = @CustomerID"
        connectionstring="<%$ ConnectionStrings:NorthWindConnectionString%>"
        runat="server">
      </asp:sqldatasource>
      
    </form>
  </body>
</html>

Remarks

Use the Keys property to access the values of the key fields (as specified by the DataKeyNames property) for a deleted record. For example, you can use these values to keep a log of deleted records.

Note

This property contains only the key fields. To access the non-key fields, use the Values property.

The Keys property returns an object that implements the System.Collections.Specialized.IOrderedDictionary interface. The object contains System.Collections.DictionaryEntry objects that represent the key fields of the deleted record.

Applies to

See also