DataBinding Class
Contains information about a single data-binding expression in an ASP.NET server control, which allows rapid-application development (RAD) designers, such as Microsoft Visual Studio, to create data-binding expressions at design time. This class cannot be inherited.
Assembly: System.Web (in System.Web.dll)
The DataBinding type exposes the following members.
| Name | Description | |
|---|---|---|
![]() | Expression | Gets or sets the data-binding expression to be evaluated. |
![]() | PropertyName | Gets the name of the ASP.NET server control property to bind data to. |
![]() | PropertyType | Gets the .NET Framework type of the data-bound ASP.NET server control property. |
| Name | Description | |
|---|---|---|
![]() | Equals | Determines whether the specified object is the same instance of the DataBinding class as the current object. (Overrides Object.Equals(Object).) |
![]() | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
![]() | GetHashCode | Retrieves the hash code for an instance of the DataBinding object. (Overrides Object.GetHashCode.) |
![]() | GetType | Gets the Type of the current instance. (Inherited from Object.) |
![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() | ToString | Returns a string that represents the current object. (Inherited from Object.) |
Each data-binding expression in a server control is represented at design time by an instance of the DataBinding class. Any server control that contains one or more data-binding expressions has a DataBindingCollection object that contains the DataBinding objects. This collection is accessible through the Control class implementing the IDataBindingsAccessor interface. When you create a custom RAD designer, use that implementation to access the collection. Any DataBinding or DataBindingCollection objects associated with a server control exist only at design time. They do not exist at run time and, therefore, are not accessible during run time.
The following code example creates a DataBinding object and sets it equal to an existing object in the control's DataBindingCollection collection that has a propertyName parameter with a value of Text. If the collection contains a DataBinding object with a propertyName value of Text, this code returns the value of the object's Expression property. If there is no such object, it returns an empty string ("").
' 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 'OnBindingsCollectionChanged 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 'WriteToFile End Class 'SimpleDesigner
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
