DataBinding 類別

定義

命名空間:

System.Web.UI

組件:

System.Web.dll

包含有關 ASP.NET 伺服器控制項中的單一資料繫結運算式的資訊，可讓 Microsoft Visual Studio 之類的快速應用程式開發 (RAD) 設計工具在設計階段建立資料繫結運算式。 此類別無法獲得繼承。

public ref class DataBinding sealed

public sealed class DataBinding

type DataBinding = class

Public NotInheritable Class DataBinding

繼承

Object

DataBinding

範例

下列程式碼範例會 DataBinding 建立 物件，並將它設定為 與控制項 DataBindingCollection 集合 propertyName 中具有 值為 Text 之參數的現有物件相等。 如果集合包含 DataBinding 值為 Text 的物件 propertyName ，則此程式碼會傳回物件的 Expression 屬性值。 如果沒有這類物件，它會傳回空字串 (「」) 。

// Create the custom class that accesses the DataBinding and
// DataBindingCollection classes at design time.
public class SimpleDesigner : System.Web.UI.Design.ControlDesigner
{
    // Create a Text property with accessors that obtain 
    // the property value from and set the property value
    // to the Text key in the DataBindingCollection class.
    public string Text
    {
        get
        {
            DataBinding myBinding = DataBindings["Text"];
            if (myBinding != null)
            {
                return myBinding.Expression;
            }
            return String.Empty;
        }
        set
        {

            if ((value == null) || (value.Length == 0))
            {
                DataBindings.Remove("Text");
            }
            else
            {

                DataBinding binding = DataBindings["Text"];

                if (binding == null)
                {
                    binding = new DataBinding("Text", typeof(string), value);
                }
                else
                {
                    binding.Expression = value;
                }
                // Call the DataBinding constructor, then add
                // the initialized DataBinding object to the 
                // DataBindingCollection for this custom designer.
                DataBinding binding1 = (DataBinding)DataBindings.SyncRoot;
                DataBindings.Add(binding);
                DataBindings.Add(binding1);
            }
            PropertyChanged("Text");
        }
    }
    protected void PropertyChanged(string propName)
    {
        IControlDesignerTag myHtmlControlDesignBehavior = this.Tag;
        
        DataBindingCollection myDataBindingCollection;
        DataBinding myDataBinding1, myDataBinding2;
        String myStringReplace1, myDataBindingExpression1, removedBinding, removedBindingAfterReplace, myDataBindingExpression2, myStringReplace2;
        string[] removedBindings1, removedBindings2;
        Int32 temp;

        if (myHtmlControlDesignBehavior == null)
            return;
        // Use the DataBindingCollection constructor to 
        // create the myDataBindingCollection1 object.
        // Then set this object equal to the
        // DataBindings property of the control created
        // by this custom designer.
        DataBindingCollection myDataBindingCollection1 = new DataBindingCollection();
        myDataBindingCollection1 = myDataBindingCollection = DataBindings;
        if (myDataBindingCollection.Contains(propName))
        {
            myDataBinding1 = myDataBindingCollection[propName];
            myStringReplace1 = propName.Replace(".", "-");
            if (myDataBinding1 == null)
            {
                myHtmlControlDesignBehavior.RemoveAttribute(myStringReplace1);
                return;
            }
            // DataBinding is not null.
            myDataBindingExpression1 = String.Concat("<%#", myDataBinding1.Expression, "%>");
            myHtmlControlDesignBehavior.SetAttribute(myStringReplace1, myDataBindingExpression1);
            int index = myStringReplace1.IndexOf("-");
        }
        else
        {
            // Use the DataBindingCollection.RemovedBindings 
            // property to set the value of the removedBindings
            // arrays.
            removedBindings2 = removedBindings1 = DataBindings.RemovedBindings;
            temp = 0;
            while (removedBindings2.Length > temp)
            {
                removedBinding = removedBindings2[temp];
                removedBindingAfterReplace = removedBinding.Replace('.', '-');
                myHtmlControlDesignBehavior.RemoveAttribute(removedBindingAfterReplace);
                temp = temp + 1;
            }
        }
        // Use the DataBindingCollection.GetEnumerator method
        // to iterate through the myDataBindingCollection object
        // and write the PropertyName, PropertyType, and Expression
        // properties to a file for each DataBinding object
        // in the MyDataBindingCollection object. 
        myDataBindingCollection = DataBindings;
        IEnumerator myEnumerator = myDataBindingCollection.GetEnumerator();

        while (myEnumerator.MoveNext())
        {
            myDataBinding2 = (DataBinding)myEnumerator.Current;
            String dataBindingOutput1, dataBindingOutput2, dataBindingOutput3;
            dataBindingOutput1 = String.Concat("The property name is ", myDataBinding2.PropertyName);
            dataBindingOutput2 = String.Concat("The property type is ", myDataBinding2.PropertyType.ToString(), "-", dataBindingOutput1);
            dataBindingOutput3 = String.Concat("The expression is ", myDataBinding2.Expression, "-", dataBindingOutput2);
            WriteToFile(dataBindingOutput3);

            myDataBindingExpression2 = String.Concat("<%#", myDataBinding2.Expression, "%>");
            myStringReplace2 = myDataBinding2.PropertyName.Replace(".", "-");
            myHtmlControlDesignBehavior.SetAttribute(myStringReplace2, myDataBindingExpression2);
            int index = myStringReplace2.IndexOf('-');
        }// while loop ends
    }
    public void WriteToFile(string input)
    {
        // The WriteToFile custom method writes
        // the values of the DataBinding properties
        // to a file on the C drive at design time.
        StreamWriter myFile = File.AppendText("C:\\DataBindingOutput.txt");
        ASCIIEncoding encoder = new ASCIIEncoding();
        byte[] ByteArray = encoder.GetBytes(input);
        char[] CharArray = encoder.GetChars(ByteArray);
        myFile.WriteLine(CharArray, 0, input.Length);
        myFile.Close();
    }
}

' Create the custom class that accesses the DataBinding and
' DataBindingCollection classes at design time.

Public Class SimpleDesigner
    Inherits System.Web.UI.Design.ControlDesigner
    ' Create a Text property with accessors that obtain 
    ' the property value from and set the property value
    ' to the Text key in the DataBindingCollection class.

    Public Property [Text]() As String
        Get
            Dim myBinding As DataBinding = DataBindings("Text")
            If Not (myBinding Is Nothing) Then
                Return myBinding.Expression
            End If
            Return String.Empty
        End Get
        Set(ByVal value As String)

            If value Is Nothing OrElse value.Length = 0 Then
                DataBindings.Remove("Text")
            Else

                Dim binding As DataBinding = DataBindings("Text")

                If binding Is Nothing Then
                    binding = New DataBinding("Text", GetType(String), value)
                Else
                    binding.Expression = value
                End If
                ' Call the DataBinding constructor, then add
                ' the initialized DataBinding object to the 
                ' DataBindingCollection for this custom designer.
                Dim binding1 As DataBinding = CType(DataBindings.SyncRoot, DataBinding)
                DataBindings.Add(binding)
                DataBindings.Add(binding1)
            End If
            PropertyChanged("Text")
        End Set
    End Property

    Protected Sub PropertyChanged(ByVal propName As String)
        Dim myHtmlControlDesignBehavior As IControlDesignerTag = Me.Tag
        Dim myDataBindingCollection As DataBindingCollection
        Dim myDataBinding1, myDataBinding2 As DataBinding
        Dim myStringReplace1, myDataBindingExpression1, removedBinding, removedBindingAfterReplace, myDataBindingExpression2, myStringReplace2 As [String]
        Dim removedBindings1(), removedBindings2() As String
        Dim temp As Int32

        If myHtmlControlDesignBehavior Is Nothing Then
            Return
        End If

        myDataBindingCollection = DataBindings
        ' Use the DataBindingCollection constructor to 
        ' create the myDataBindingCollection1 object.
        ' Then set this object equal to the
        ' DataBindings property of the control created
        ' by this custom designer.
        Dim myDataBindingCollection1 As New DataBindingCollection()
        myDataBindingCollection1 = DataBindings
        myDataBindingCollection = DataBindings
        If (myDataBindingCollection.Contains(propName)) Then
            myDataBinding1 = myDataBindingCollection(propName)
            myStringReplace1 = propName.Replace(".", "-")
            If myDataBinding1 Is Nothing Then
                myHtmlControlDesignBehavior.RemoveAttribute(myStringReplace1)
                Return
            End If
            ' DataBinding is not null.
            myDataBindingExpression1 = [String].Concat("<%#", myDataBinding1.Expression, "%>")
            myHtmlControlDesignBehavior.SetAttribute(myStringReplace1, myDataBindingExpression1)
            Dim index As Integer = myStringReplace1.IndexOf("-")
        Else
            ' Use the DataBindingCollection.RemovedBindings 
            ' property to set the value of the removedBindings
            ' arrays.
            removedBindings1 = DataBindings.RemovedBindings
            removedBindings2 = DataBindings.RemovedBindings
            temp = 0
            While removedBindings2.Length > temp
                removedBinding = removedBindings2(temp)
                removedBindingAfterReplace = removedBinding.Replace("."c, "-"c)
                myHtmlControlDesignBehavior.RemoveAttribute(removedBindingAfterReplace)
                temp = temp & 1
            End While
        End If
        ' Use the DataBindingCollection.GetEnumerator method
        ' to iterate through the myDataBindingCollection object
        ' and write the PropertyName, PropertyType, and Expression
        ' properties to a file for each DataBinding object
        ' in the MyDataBindingCollection object. 
        myDataBindingCollection = DataBindings
        Dim myEnumerator As IEnumerator = myDataBindingCollection.GetEnumerator()

        While myEnumerator.MoveNext()
            myDataBinding2 = CType(myEnumerator.Current, DataBinding)
            Dim dataBindingOutput1, dataBindingOutput2, dataBindingOutput3 As [String]
            dataBindingOutput1 = [String].Concat("The property name is ", myDataBinding2.PropertyName)
            dataBindingOutput2 = [String].Concat("The property type is ", myDataBinding2.PropertyType.ToString(), "-", dataBindingOutput1)
            dataBindingOutput3 = [String].Concat("The expression is ", myDataBinding2.Expression, "-", dataBindingOutput2)
            WriteToFile(dataBindingOutput3)

            myDataBindingExpression2 = [String].Concat("<%#", myDataBinding2.Expression, "%>")
            myStringReplace2 = myDataBinding2.PropertyName.Replace(".", "-")
            myHtmlControlDesignBehavior.SetAttribute(myStringReplace2, myDataBindingExpression2)
            Dim index As Integer = myStringReplace2.IndexOf("-"c)
        End While ' while loop ends
    End Sub
    Public Sub WriteToFile(ByVal input As String)
        ' The WriteToFile custom method writes
        ' the values of the DataBinding properties
        ' to a file on the C drive at design time.
        Dim myFile As StreamWriter = File.AppendText("C:\DataBindingOutput.txt")
        Dim encoder As New ASCIIEncoding()
        Dim ByteArray As Byte() = encoder.GetBytes(input)
        Dim CharArray As Char() = encoder.GetChars(ByteArray)
        myFile.WriteLine(CharArray, 0, input.Length)
        myFile.Close()
    End Sub
End Class

備註

伺服器控制項中的每個資料系結運算式都會在設計階段由 類別的 DataBinding 實例表示。 包含一或多個資料系結運算式的任何伺服器控制項都有 DataBindingCollection 包含 物件的 物件 DataBinding 。 這個集合可透過實作 介面的 ControlIDataBindingsAccessor 類別來存取。 當您建立自訂 RAD 設計工具時，請使用該實作來存取集合。 與伺服器控制項相關聯的任何 DataBinding 或 DataBindingCollection 物件，只存在於設計階段。 它們不存在於執行時間，因此無法在執行時間期間存取。

建構函式

DataBinding(String, Type, String)

初始化 DataBinding 類別的新執行個體。

屬性

Expression	取得或設定要評估的資料繫結運算式。
PropertyName	取得要對它繫結資料的 ASP.NET 伺服器控制項屬性名稱。
PropertyType	取得資料繫結 ASP.NET 伺服器控制項屬性的 NET Framework 型別。

方法

Equals(Object)	判斷指定物件是否為做為目前物件的 DataBinding 類別的相同執行個體。
GetHashCode()	為 DataBinding 物件的執行個體擷取雜湊程式碼。
GetType()	取得目前執行個體的 Type。 (繼承來源 Object)
MemberwiseClone()	建立目前 Object 的淺層複製。 (繼承來源 Object)
ToString()	傳回代表目前物件的字串。 (繼承來源 Object)

另請參閱

• DataBinder
• DataBindingCollection
• IDataBindingsAccessor