BindingSource.Filter 属性

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

获取或设置用于筛选查看哪些行的表达式。

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

public virtual string Filter { get; set; }

member this.Filter : string with get, set

Public Overridable Property Filter As String

属性值

String

用于指定行的筛选方式的字符串。 默认值为 null。

实现

Filter

示例

以下示例演示如何将 属性与 一 Filter 起使用 DataView。 若要运行此示例，请将代码粘贴到 Windows 窗体中，然后从窗体的构造函数或Load事件处理方法调用 PopulateDataViewAndFilter 。 窗体应导入 System.Xml 和 System.IO 命名空间。

private void PopulateDataViewAndFilter()
{
    DataSet set1 = new DataSet();

    // Some xml data to populate the DataSet with.
    string musicXml =
        "<?xml version='1.0' encoding='UTF-8'?>" +
        "<music>" +
        "<recording><artist>Coldplay</artist><cd>X&Y</cd></recording>" +
        "<recording><artist>Dave Matthews</artist><cd>Under the Table and Dreaming</cd></recording>" +
        "<recording><artist>Dave Matthews</artist><cd>Live at Red Rocks</cd></recording>" +
        "<recording><artist>Natalie Merchant</artist><cd>Tigerlily</cd></recording>" +
        "<recording><artist>U2</artist><cd>How to Dismantle an Atomic Bomb</cd></recording>" +
        "</music>";

    // Read the xml.
    StringReader reader = new StringReader(musicXml);
    set1.ReadXml(reader);

    // Get a DataView of the table contained in the dataset.
    DataTableCollection tables = set1.Tables;
    DataView view1 = new DataView(tables[0]);

    // Create a DataGridView control and add it to the form.
    DataGridView datagridview1 = new DataGridView();
    datagridview1.AutoGenerateColumns = true;
    this.Controls.Add(datagridview1);

    // Create a BindingSource and set its DataSource property to
    // the DataView.
    BindingSource source1 = new BindingSource();
    source1.DataSource = view1;

    // Set the data source for the DataGridView.
    datagridview1.DataSource = source1;

    //The Filter string can include Boolean expressions.
    source1.Filter = "artist = 'Dave Matthews' OR cd = 'Tigerlily'";
}

Private Sub PopulateDataViewAndFilter() 
    Dim set1 As New DataSet()
    
    ' Some xml data to populate the DataSet with.
    Dim musicXml As String = "<?xml version='1.0' encoding='UTF-8'?>" & _
        "<music>" & _
        "<recording><artist>Coldplay</artist><cd>X&Y</cd></recording>" & _
        "<recording><artist>Dave Matthews</artist><cd>Under the Table and Dreaming</cd></recording>" & _
        "<recording><artist>Dave Matthews</artist><cd>Live at Red Rocks</cd></recording>" & _
        "<recording><artist>Natalie Merchant</artist><cd>Tigerlily</cd></recording>" & _
        "<recording><artist>U2</artist><cd>How to Dismantle an Atomic Bomb</cd></recording>" & _
        "</music>"
    
    ' Read the xml.
    Dim reader As New StringReader(musicXml)
    set1.ReadXml(reader)
    
    ' Get a DataView of the table contained in the dataset.
    Dim tables As DataTableCollection = set1.Tables
    Dim view1 As New DataView(tables(0))
    
    ' Create a DataGridView control and add it to the form.
    Dim datagridview1 As New DataGridView()
    datagridview1.AutoGenerateColumns = True
    Me.Controls.Add(datagridview1)
    
    ' Create a BindingSource and set its DataSource property to
    ' the DataView.
    Dim source1 As New BindingSource()
    source1.DataSource = view1
    
    ' Set the data source for the DataGridView.
    datagridview1.DataSource = source1
    
    ' The Filter string can include Boolean expressions.
    source1.Filter = "artist = 'Dave Matthews' OR cd = 'Tigerlily'"

End Sub

注解

通常用于复杂的数据绑定方案， Filter 属性允许查看 的 DataSource子集。 只有实现 IBindingListView 接口的基础列表支持筛选。

当 不是 null时Filter，会将BindingSource此属性传递给基础列表。 如果在对象初始化期间设置此属性，则调用将推迟到初始化完成后。

若要形成筛选值，请指定列的名称，后跟运算符和要筛选的值。 接受的筛选器语法取决于基础数据源。 如果基础数据源是 DataSet、 DataTable或 DataView，则可以使用为 DataColumn.Expression 属性记录的语法指定布尔表达式。

属性的值 Filter 会影响属性的值 Count 。 此外，当数据源更改时， Filter 该值将保留。 若要停止筛选 ， DataSource请调用 RemoveFilter 方法。

另请参阅

• DataSource
• List
• Sort
• RemoveFilter()
• IsSorted