BindingSource.Filter 属性
重要
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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); };C#
public virtual string Filter { get; set; }C#
public virtual string? Filter { get; set; }member this.Filter : string with get, setPublic Overridable Property Filter As String用于指定行的筛选方式的字符串。 默认值为 null。
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。
C#
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
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。
| 产品 | 版本 |
|---|---|
| .NET Framework | 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
| Windows Desktop | 3.0, 3.1, 5, 6, 7, 8, 9, 10 |
