how to retain value in custom textbox after postaback

I made the following control that inherits from WebControl

Code:

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Imports Microsoft.VisualBasic
Imports System
Imports System.Web.UI
Imports System.Web.UI.WebControls



Public Class tb
    Inherits WebControl

    Protected _labelText As String
    Protected _value As String
    Protected _name As String

    Public Property LabelText() As String
        Get
            Return _labelText
        End Get
        Set(ByVal value As String)
            _labelText = value
        End Set
    End Property

    Public Property Value() As String
        Get
            Return _value
        End Get
        Set(ByVal value As String)
            _value = value
        End Set
    End Property

    Public Property Name() As String
        Get
            Return _name
        End Get
        Set(ByVal value As String)
            _name = value
        End Set
    End Property


    Protected Overrides Sub RenderContents(ByVal writer As HtmlTextWriter)


        Dim tmp As String = "<label for='" & Name & "'>" & LabelText & "</label><input id='" & Name & "' type='text' value='" & Value & "' />"

        writer.Write(tmp)

    End Sub


    Protected Overridable Function GetValue(ByVal Collection As Collections.Specialized.NameValueCollection) As Boolean


            Me.Value = HttpContext.Current.Request(Name)


        Return True

    End Function


    Protected Sub Page_Init(ByVal Sender As Object, ByVal E As EventArgs) Handles Me.Init

        GetValue(Page.Request.Form)

    End Sub



End Class

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then in my default.aspx.vb file I have

Code:

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Dim newTB As tb = New tb

        newTB.Name = "cat"
        newTB.LabelText = "My cat's name "

        placeholder.Controls.Add(newTB)

---

I don't understand why the value of the textbox isn't retained after postback
I tried to inherit directly from TextBox but then the render doesn't stick and the label doesn't appear.

Does anyone know what I can do to make this work?

bsw

It isn't retained because you are explicitly writing it out to the browser. As a result, ASP.NET has no idea of its existence and so you'll have to maintain its value yourself.

When you use writer.write() and write out some HTML as you're doing, think ASP/PHP: It won't maintain the values for you.

hi mendhak

Thanks for the reply

I knew that I was to track it myself but I forgot to add the name attribute. Now it works.

Code:

---

Public Class tb
    Inherits WebControl

    Protected _labelText As String
    Protected _value As String
    Protected _name As String

    Public Property LabelText() As String
        Get
            Return _labelText
        End Get
        Set(ByVal value As String)
            _labelText = value
        End Set
    End Property

    Public Property Value() As String
        Get
            Return _value
        End Get
        Set(ByVal value As String)
            _value = value
        End Set
    End Property

    Public Property Name() As String
        Get
            Return _name
        End Get
        Set(ByVal value As String)
            _name = value
        End Set
    End Property


    Protected Overrides Sub RenderContents(ByVal writer As HtmlTextWriter)

        Dim tmp As String = "<label for='cat'>" & _labelText & "</label><input name='" & _name & "' id='" & _name & "' type='text' value='" & _value & "' runat='server' />"

        writer.Write(tmp)

    End Sub



    Protected Sub Page_Init(ByVal Sender As Object, ByVal E As EventArgs) Handles Me.Init
        If Not GetValue(Page.Request.Form) Then
            GetValue(Page.Request.QueryString)
        End If
    End Sub

    Protected Overridable Function GetValue(ByVal Collection As Collections.Specialized.NameValueCollection) As Boolean

        For Each Key As String In Collection.AllKeys
            If Key = _name Then
                Me.Value = Page.Server.HtmlEncode(Collection(Key)).Trim
                Return True
            End If
        Next
        Return False
    End Function
End Class

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Wahey. :)