ObjectDataSourceView.FilterExpression 屬性

參考

定義

命名空間:: System.Web.UI.WebControls

組件:: System.Web.dll

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

取得或設定呼叫 SelectMethod 屬性所識別之商務物件方法時套用的篩選條件運算式。

public:
 property System::String ^ FilterExpression { System::String ^ get(); void set(System::String ^ value); };

public string FilterExpression { get; set; }

member this.FilterExpression : string with get, set

Public Property FilterExpression As String

屬性值

String

字串，表示使用 SelectMethod 屬性所識別之商務物件方法擷取資料時套用的篩選條件運算式。

例外狀況

NotSupportedException

設定了 FilterExpression 屬性，且 Select(DataSourceSelectArguments) 方法沒有傳回 DataSet。

範例

本節包含兩個程式碼範例。第一個程式碼範例示範如何使用控制項顯示篩選的資料，以從仲介層商務物件擷取資料 ObjectDataSource ，以及 GridView 顯示結果的控制項。第二個程式碼範例提供第一個程式碼範例中使用的仲介層商務物件範例。

下列程式碼範例示範如何使用控制項顯示篩選的資料，以從仲介層商務物件擷取資料 ObjectDataSource ，以及 GridView 顯示結果的控制項。 ObjectDataSource只有當擷取資料的方法擷取資料做為 DataSet 物件時，控制項才能篩選資料。基於這個理由， SelectMethod 屬性會識別將資料擷取為 DataSet 的商務物件方法。

程式碼範例包含 TextBox 、 GridView 控制項、 ObjectDataSource 控制項和 [提交] 按鈕。根據預設，會 TextBox 填入其中一個 Northwind Traders 員工的名稱。會顯示 GridView 中 TextBox 名稱所識別之員工的相關資訊。若要擷取另一位員工的資料，請在中 TextBox 輸入員工的完整名稱，然後按一下 [ 提交 ] 按鈕。

屬性 FilterExpression 會指定運算式，用來篩選屬性所擷 SelectMethod 取的資料。它會使用評估為集合中所含參數的參數 FilterParameters 預留位置。在此範例中，參數預留位置會以單引號系結，因為參數的類型是可能包含空格的字串類型。如果參數的類型是數值或日期類型，則不需要周框引號。

<%@ 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">
<script runat="server">

    protected void ObjectDataSource1_Filtering(object sender, ObjectDataSourceFilteringEventArgs e)
    {
        if (Textbox1.Text == "")
        {
            e.ParameterValues.Clear();
            e.ParameterValues.Add("FullName", "Nancy Davolio");
        }
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>ObjectDataSource - C# Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <p>Show all users with the following name.</p>

        <asp:textbox id="Textbox1" runat="server" text="Nancy Davolio" />

        <asp:gridview
          id="GridView1"
          runat="server"
          datasourceid="ObjectDataSource1"
          autogeneratecolumns="False">
          <columns>
            <asp:boundfield headertext="ID" datafield="EmpID" />
            <asp:boundfield headertext="Name" datafield="FullName" />
            <asp:boundfield headertext="Street Address" datafield="Address" />
          </columns>
        </asp:gridview>

        <!-- Security Note: The ObjectDataSource uses a FormParameter,
             Security Note: which does not perform validation of input from the client. -->

        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployeesAsDataSet"
          typename="Samples.AspNet.CS.EmployeeLogic"
          filterexpression="FullName='{0}'" OnFiltering="ObjectDataSource1_Filtering">
            <filterparameters>
              <asp:formparameter name="FullName" formfield="Textbox1" defaultvalue="Nancy Davolio" />
            </filterparameters>
        </asp:objectdatasource>

        <p><asp:button id="Button1" runat="server" text="Search" /></p>

    </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">
<script runat="server">

    Protected Sub ObjectDataSource1_Filtering(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.ObjectDataSourceFilteringEventArgs)
        If Textbox1.Text = "" Then
            e.ParameterValues.Clear()
            e.ParameterValues.Add("FullName", "Nancy Davolio")
        End If
    End Sub
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>ObjectDataSource - VB Example</title>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">

        <p>Show all users with the following name.</p>

        <asp:textbox id="Textbox1" runat="server" text="Nancy Davolio" />

        <asp:gridview
          id="GridView1"
          runat="server"
          datasourceid="ObjectDataSource1"
          autogeneratecolumns="False">
          <columns>
            <asp:boundfield headertext="ID" datafield="EmpID" />
            <asp:boundfield headertext="Name" datafield="FullName" />
            <asp:boundfield headertext="Street Address" datafield="Address" />
          </columns>
        </asp:gridview>

        <!-- Security Note: The ObjectDataSource uses a FormParameter,
             Security Note: which does not perform validation of input from the client. -->

        <asp:objectdatasource
          id="ObjectDataSource1"
          runat="server"
          selectmethod="GetAllEmployeesAsDataSet"
          typename="Samples.AspNet.VB.EmployeeLogic"
          filterexpression="FullName='{0}'" OnFiltering="ObjectDataSource1_Filtering">
            <filterparameters>
              <asp:formparameter name="FullName" formfield="Textbox1" defaultvalue="Nancy Davolio" />
            </filterparameters>
        </asp:objectdatasource>

        <p><asp:button id="Button1" runat="server" text="Search" /></p>

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

下列程式碼範例提供上述程式碼範例所使用的仲介層商務物件範例。程式碼範例包含兩個基本類別：

類別 EmployeeLogic ，這是封裝商務邏輯的類別。
類別 NorthwindEmployee ，這是一個模型類別，其中包含從資料層載入和保存資料所需的基本功能。

為了簡單起見，類別 EmployeeLogic 會建立靜態資料集，而不是從資料層擷取資料。此範例也很有説明，因為此範例依賴您提供 Northwind Traders 員工的完整名稱來示範篩選。

如需完整的工作範例，您必須編譯並使用這些類別搭配提供的Web Form頁程式碼範例。

namespace Samples.AspNet.CS {

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

    // Returns a collection of NorthwindEmployee objects.
    public static ICollection GetAllEmployees () {
      ArrayList data = new ArrayList();
           
      data.Add(new NorthwindEmployee(1,"Nancy","Davolio","507 - 20th Ave. E. Apt. 2A"));
      data.Add(new NorthwindEmployee(2,"Andrew","Fuller","908 W. Capital Way"));
      data.Add(new NorthwindEmployee(3,"Janet","Leverling","722 Moss Bay Blvd."));
      data.Add(new NorthwindEmployee(4,"Margaret","Peacock","4110 Old Redmond Rd."));
      data.Add(new NorthwindEmployee(5,"Steven","Buchanan","14 Garrett Hill"));
      data.Add(new NorthwindEmployee(6,"Michael","Suyama","Coventry House Miner Rd."));
      data.Add(new NorthwindEmployee(7,"Robert","King","Edgeham Hollow Winchester Way"));
      
      return data;
    }
    
    public static NorthwindEmployee GetEmployee(object anID) {
      ArrayList data = GetAllEmployees() as ArrayList;     
      int empID = Int32.Parse(anID.ToString());      
      return data[empID] as NorthwindEmployee;
    }

    // 
    // To support basic filtering, the employees cannot
    // be returned as an array of objects, rather as a 
    // DataSet of the raw data values. 
    public static DataSet GetAllEmployeesAsDataSet () {
      ICollection employees = GetAllEmployees();
      
      DataSet ds = new DataSet("Table");
      
      // Create the schema of the DataTable.
      DataTable dt = new DataTable();
      DataColumn dc;
      dc = new DataColumn("EmpID",   typeof(int));    dt.Columns.Add(dc);
      dc = new DataColumn("FullName",typeof(string)); dt.Columns.Add(dc);
      dc = new DataColumn("Address", typeof(string)); dt.Columns.Add(dc);
      
      // Add rows to the DataTable.
      DataRow row;
            
      foreach (NorthwindEmployee ne in employees) {                
        row = dt.NewRow();
        row["EmpID"]    = ne.EmpID;
        row["FullName"] = ne.FullName;
        row["Address"]  = ne.Address;
        dt.Rows.Add(row);
      } 
      // Add the complete DataTable to the DataSet.
      ds.Tables.Add(dt);
      
      return ds;
    }    
  }

  public class NorthwindEmployee {

    public NorthwindEmployee (int anID, 
                              string aFirstName,
                              string aLastName,
                              string anAddress) {
      ID = anID;
      firstName = aFirstName;
      lastName = aLastName;   
      address = anAddress;
    }

    private object ID;
    public string EmpID {
      get { return ID.ToString();  }
    }

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

    private string firstName;
    public string FirstName {
      get { return firstName; }
      set { firstName = value;  }
    }
    
    public string FullName {
      get { return FirstName  + " " +  LastName; }
    }
    
    private string address;
    public string Address {
      get { return address; }
      set { address = value;  }
    }    
  }
}

Imports System.Collections
Imports System.Data
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.
'
Public Class EmployeeLogic
   
   ' Returns a collection of NorthwindEmployee objects.
   Public Shared Function GetAllEmployees() As ICollection
      Dim data As New ArrayList()
      
      data.Add(New NorthwindEmployee(1, "Nancy", "Davolio", "507 - 20th Ave. E. Apt. 2A"))
      data.Add(New NorthwindEmployee(2, "Andrew", "Fuller", "908 W. Capital Way"))
      data.Add(New NorthwindEmployee(3, "Janet", "Leverling", "722 Moss Bay Blvd."))
      data.Add(New NorthwindEmployee(4, "Margaret", "Peacock", "4110 Old Redmond Rd."))
      data.Add(New NorthwindEmployee(5, "Steven", "Buchanan", "14 Garrett Hill"))
      data.Add(New NorthwindEmployee(6, "Michael", "Suyama", "Coventry House Miner Rd."))
      data.Add(New NorthwindEmployee(7, "Robert", "King", "Edgeham Hollow Winchester Way"))
      
      Return data
   End Function 'GetAllEmployees
   
   
   Public Shared Function GetEmployee(anID As Object) As NorthwindEmployee
      Dim data As ArrayList = CType(GetAllEmployees(), ArrayList)
      Dim empID As Integer = Int32.Parse(anID.ToString())
      Return CType(data(empID),NorthwindEmployee)   
   End Function 'GetEmployee
   
   
   ' To support basic filtering, the employees cannot
   ' be returned as an array of objects, rather as a 
   ' DataSet of the raw data values. 
   Public Shared Function GetAllEmployeesAsDataSet() As DataSet
      Dim employees As ICollection = GetAllEmployees()
      
      Dim ds As New DataSet("Table")
      
      ' Create the schema of the DataTable.
      Dim dt As New DataTable()
      Dim dc As DataColumn
      dc = New DataColumn("EmpID", GetType(Integer))
      dt.Columns.Add(dc)
      dc = New DataColumn("FullName", GetType(String))
      dt.Columns.Add(dc)
      dc = New DataColumn("Address", GetType(String))
      dt.Columns.Add(dc)
      
      ' Add rows to the DataTable.
      Dim row As DataRow
      Dim ne As NorthwindEmployee
      For Each ne In employees         
         row = dt.NewRow()
         row("EmpID") = ne.EmpID
         row("FullName") = ne.FullName
         row("Address") = ne.Address
         dt.Rows.Add(row)
      Next
      ' Add the complete DataTable to the DataSet.
      ds.Tables.Add(dt)
      
      Return ds
   End Function 'GetAllEmployeesAsDataSet
      
End Class


Public Class NorthwindEmployee
   
   Public Sub New(anID As Integer, aFirstName As String, aLastName As String, anAddress As String)
      ID = anID
      Me.aFirstName = aFirstName
      Me.aLastName = aLastName
      Me.aAddress = anAddress
   End Sub
   
   Private ID As Object   
   Public ReadOnly Property EmpID() As String
      Get
         Return ID.ToString()
      End Get
   End Property 

   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 
   
   Public ReadOnly Property FullName() As String
      Get
         Return FirstName & " " & LastName
      End Get
   End Property 
  
   Private aAddress As String  
   Public Property Address() As String
      Get
         Return aAddress
      End Get
      Set
         aAddress = value
      End Set
   End Property 
   
End Class
End Namespace

備註

只有當方法傳 DataSet 回、 DataView 或 DataTable 物件時 Select ，控制項 ObjectDataSource 才支援篩選資料。

屬性所使用的 FilterExpression 語法是格式字串樣式表達式。篩選運算式語法是屬性所 RowFilter 接受的相同語法，因為篩選運算式會套用至 RowFilter 從執行 Select 方法傳回之物件的屬性 DataView 。 (如需詳細資訊，請參閱 Expression .) 如果您將參數新增至 FilterParameters 集合，您也可以在運算式中包含格式字串預留位置，例如 "{0}" ，在運算式中取代參數值。預留位置會根據集合中 FilterParameters 參數的索引來取代。

您可以在中包含 FilterExpression 參數。如果參數的類型是字串或字元類型，請將參數括在單引號中。如果參數是數數值型別，則不需要引號。 FilterParameters集合包含針對中找到 FilterExpression 的預留位置評估的參數。

屬性的值 FilterExpression 會儲存在檢視狀態中。

重要

建議您驗證您從用戶端接收的任何篩選參數值。執行時間只會將參數值取代為篩選運算式，並將它套用至 DataView 方法所傳 Select 回的物件。如果您使用 FilterExpression 屬性做為安全性量值來限制傳回的專案數，則必須在篩選發生之前驗證參數值。

適用於

另請參閱

FilterParameters

共用方式為

ObjectDataSourceView.FilterExpression 屬性

定義

屬性值

例外狀況

範例

備註

適用於

另請參閱

其他資源