Custom server control from datalist not binding

Question

User-1304029052 posted

I'm new to creating custom controls to bear with me....

I have a control inherited from datalist because I want all the same functionality but with a couple of extra properties.

I have a method that goes off and gets the data inside the control (instead of using a separate datasource ID).  It's reading it from XML into a datatable.

 

If on the code behind of the aspx page I put the control on I put a thecontrol.databind() in the page load, all works well.

However I'd rather not have to do this, instead the control should bind itself.

 

I gather it's something to do with the order of events but I'm not sure what to do about it.

I don't want to reinvent the datalist wheel, just add a couple of properties and get it's own data

 

Sample code (some code removed for clarity)

 

        ''' <summary>
        ''' Server control to place content from a Region onto the web page
        ''' </summary>
        <DesignerAttribute(GetType(RegionDesignTime)), DefaultProperty("Text"), _
    ToolboxData("<{0}:ctrlRegion runat=server RegionID=1 RepeatLayout=Flow><HeaderTemplate></HeaderTemplate><ItemTemplate><%#DataBinder.Eval(Container.DataItem, ""region_content"")%></ItemTemplate></{0}:ctrlRegion>"), _
    Bindable(True)> _
            Public Class ctrlRegion
            Inherits System.Web.UI.WebControls.DataList

#Region "Fields"
            Private _RegionID As Int32 = 0
            Private _HTMLContent As String = String.Empty
#End Region

#Region "Properties"
            ''' <summary>
            ''' The Region to retrieve from the datastore
            ''' </summary>
            <Bindable(True), Category("WCE"), DefaultValue("0"), Localizable(True), Description("Content region")> _
            Property RegionID() As Int32
                Get
                    Return _RegionID
                End Get
                Set(ByVal value As Int32)
                    If value = 0 Then
                        Throw New InvalidProgramException("The RegionID of the Region control must be greater than 0")
                    End If
                    _RegionID = value
                End Set
            End Property

            ''' <summary>
            ''' Holds the HTML content of the region ready to be displayed or saved to the datastore
            ''' </summary>
            Property HTMLContent() As String
                Get
                    Return _HTMLContent
                End Get
                Set(ByVal value As String)
                    _HTMLContent = value
                End Set
            End Property
#End Region

#Region "Methods"
            Public Sub New()
                Retrieve(RegionID)
            End Sub


            ''' <summary>
            ''' Retrieves the Region content from the data source into its HTMLContent property
            ''' </summary>
            Public Sub Retrieve(ByVal Region_id As Integer)

                Dim dtRegions As New DataTable("dtRegions")


' Goes off and gets the data into dtRegion here
'
'
'



                Dim query = _
                    From tbRegion In dtRegions.AsEnumerable() _
                    Where tbRegion.Field(Of Int32)("Region_id") = RegionID _
                    Select tbRegion

                Dim view As DataView = query.AsDataView()
                MyBase.DataSource = view
                MyBase.DataBind()
                DataBind()

            End Sub
#End Region

        End Class

        ''' <summary>
        ''' Design time representation of the control
        ''' </summary>
        Public Class RegionDesignTime
            Inherits ControlDesigner
            Public Overrides Function GetDesignTimeHtml() As String

                Dim designTimeHtml As String = ""
                Dim myControl As ctrlRegion = CType(ViewControl, ctrlRegion)
                designTimeHtml = String.Format("Region : {0}<br />", myControl.RegionID)
                Return designTimeHtml
            End Function

        End Class

 

Answer 1

User-1304029052 posted

Found the answer now. I  had to put the databind inside the preRender

 

Private Sub ctrlRegion_DataBinding(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.DataBinding
                Retrieve()
            End Sub

            Private Sub ctrlRegion_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender
                If Page.IsPostBack Then
                    'Do nothing
                Else
                    Me.DataBind()
                End If
            End Sub