My button is not getting enabled again.

I want to enable the my_btn button when the text in my_txt changes, but it's not working.

here's my code

<asp:Button ID="my_btn" runat="server" text="BUTTON" UseSubmitBehavior="False" />
<cc1:TBoxBaseCTL ID="my_txt" runat="server" AutoPostBack="false" HasLoadFromXml="True"></cc1:TBoxBaseCTL>

Private Sub my_btn_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles my_btn.Click
    my_btn.Enabled = False
End Sub

Private Sub mytxtChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles my_txt.TextChanged
    my_btn.Enabled = True
End Sub

I expected the my_btn button to be enabled again when the text in mytxt changes or focusout. However, even after changing the text, the button remains disabled. I tried using the TextChanged event of mytxt, but it doesn't seem to trigger as expected. I also checked that AutoPostBack is set to true.

My button is not getting enabled again.

I want to enable the my_btn button when the text in my_txt changes, but it's not working.

here's my code

<asp:Button ID="my_btn" runat="server" text="BUTTON" UseSubmitBehavior="False" />
<cc1:TBoxBaseCTL ID="my_txt" runat="server" AutoPostBack="false" HasLoadFromXml="True"></cc1:TBoxBaseCTL>

Private Sub my_btn_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles my_btn.Click
    my_btn.Enabled = False
End Sub

Private Sub mytxtChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles my_txt.TextChanged
    my_btn.Enabled = True
End Sub

I expected the my_btn button to be enabled again when the text in mytxt changes or focusout. However, even after changing the text, the button remains disabled. I tried using the TextChanged event of mytxt, but it doesn't seem to trigger as expected. I also checked that AutoPostBack is set to true.

• asp
• vb
• webforms
• postback
• textchanged

• 2 What does not getting enabled again. mean? This is a web app, not Windows Forms. Changing a component attribute has no effect until the page is re-rendered. The server code won't be called at all until the page is submitted to the server. And nothing seems to bind mytxtChanged to the custom control's TBoxBaseCTL.TextChanged event anyway. Does it even have such an event? Even if it does, AutoPostBack="false" means text changes won't trigger a postback to the server, so mytxtChanged wouldn't run even if it was bound – Panagiotis Kanavos Commented Apr 2 at 7:34
• 1 I don't do Web Forms development but I do notice that you say "I also checked that AutoPostBack is set to true" when that attribute for the text box is actually false. – jmcilhinney Commented 2 days ago
• 1 This is not JUST a text box but looks to be a textbox inside of a user control, and that's a big mount everest of an important detail. This means the event stub has to be placed in the user control code behind, and not the existing page code behind. One can however add a custom event to the user control that runs code behind on the host page and not in user control code behind. – Albert D. Kallal Commented 2 days ago
• 1 If the button only needs to be enabled/disabled in the UI, I suggest doing it in JavaScript on the client. – Andrew Morton Commented 2 days ago
• 1 @AndrewMorton - client side enable/disable is often a great idea. However, keep in mind that automatic view state does not work for a button. So, if you enable/disable a button with code behind, then the setting persists between post-backs. If you done client side, then on next post back, that enable/disable setting is lost. So, it kind of depends on the goal, and if the page will have to persist that setting after a round trip. If page (and that button "enabled" setting) needs to survive round trips, then often server side code is preferred, since then you don't have to keep track settings – Albert D. Kallal Commented 2 days ago

1 Answer 1

First up, you don't really just have a text box, but you have what looks to be a user control. This post thus becomes a rather different question.

As a general rule, a user control might be a grid, a dialog popup, or anything you can imagine. As a result, you can not "just out of the blue" try to attach events to the UC when it is dropped into a given page.

So, controls "contained" and controls "placed into" a UC all have of their own events, but MORE important is those events will run in the code behind in the user control code module, and NOT the current host page that you happen to place (or drag + drop) into that given page.

So, I suppose we could try and "hard code" the Button name (id) into the UC, but that kind of defeats the whole purpose of the UC and re-usable code, right?

So, what we really need to do is add a new custom "event" to the user control, and thus like any drop down list, or button, or anything else you drop into a given page? Well, each of those controls thus have a event stubs you can add, and the event code you add NOW BELONGS to the current page, and not to the code behind for the given control.

Hence, assuming we have a re-usable custom text box (a User Control)?

Well, it does stand to reason that we may well want a text changed event, for the current page - not just as pointed out, the textbox event code for the UC.

I suppose if the "only" goal was that you always are to specify some button for that UC to disable? Then you could consider adding a property setting to the UC control that is to specify the button to enable/disable. This can work well.

Or, we simply add a custom event to the UC textbox control, and then you can run or do anything you want with that event. Hence, this 2nd idea makes the most sense.

Ok, keeping this as simple as possible? And adding provisions for a MyTextChanged event that allows code in the "host" page to run when text changed in the code behind for the UC runs? Then this should work:

User control markup. The markup includes a label, and a text box.

So, we can also set the label in the UC. And even markup, or code behind in the host page can freely set that label text.

Hence this markup:

        <asp:Label ID="Lbl1" runat="server" Text="">
        </asp:Label>

        <br />

        <asp:TextBox ID="txt1" runat="server"
            TextMode="MultiLine"
            OnTextChanged="txt1_TextChanged" 
            AutoPostBack="true"
            Height="128px" 
            Width="375px">
        </asp:TextBox>

Note close, we ALREADY have wired up a event stub for the text changed event. This will run code behind in the UC.

So, now the code behind for the UC:

        Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        End Sub


        Public Property Text As String
            Get
                Return Me.txt1.Text
            End Get
            Set(value As String)
                Me.txt1.Text = value
            End Set
        End Property


        Public Property LableText As String
            Get
                Return Me.Lbl1.Text
            End Get
            Set(value As String)
                Me.Lbl1.Text = value
            End Set
        End Property

        Protected Sub txt1_TextChanged(sender As Object, e As EventArgs)

            ' this will trigger a event on the hosted page when text changes

            RaiseEvent MyTextChanged(sender, e)

        End Sub


        <Category("Events")>
        <Description("On Text Changed Event")>
        Public Event MyTextChanged(sender As Object, e As EventArgs)

Note the last part - we added a public custom event called MytextChanged to the UC. This is the custom new event that we can now use in the page that "contains" or "hosts" the UC.

So, now let's write some code to disable a button on the page when the custom UC text box text changes.

So, all we need is a button on the page, and then to drag + drop in the UC to the page.

Hence this:

So we now have this markup:

            <asp:Button ID="Button1" runat="server" Text="Button"
                style="float:left"
                />
            <br />
            <br />
            <br />
            <uc1:MyTextBox runat="server" ID="MyTextBox"
                LableText="Enter some text into box"

                
                
                />

We need to add the custom event. You can do this by using inteli-sense and type in the name of our custom new event. So, start typing in the name of our custom event (MyTextChanged), and when you hit "=", note the prompt to create a new event - click on that.

It will look like this in the editor:

So, we just added a new event stub, but on the CURRENT page, and one what will run when the text box changes. The only issue here (been this way for 20 years), is the code stub generated for some reason is missing the parameters. So, flip to code behind, and we have this:

    Protected Sub MyTextBox_MyTextChanged()


    End Sub

Now, above will work, but I suggest you just find some other control and steal and grab the two parameters that all such events have. So above now becomes this:

Protected Sub MyTextBox_MyTextChanged(sender As Object, e As EventArgs)

End Sub

(keep in mind, even without the parameters, the above would have worked, but having all such events in near all cases do have 2 parameters - I suggest you try and keep that design pattern).

So, now with our code to disable the button, we now have this:

    Protected Sub MyTextBox_MyTextChanged(sender As Object, e As EventArgs)

        Me.Button1.Enabled = False

    End Sub

And the whole result is thus now this:

Note how I type in some text, but when I hit tab, the button becomes disabled:

So, just keep in mind that the text changed event of the UC will run code behind in the UC code module, not in the existing page. You have to expose a public "event" for the UC to run a code stub in the hosting page (the page you dropped the UC control into).

Last but not least? We really don't know what kind of control you are using here, and your control of:

<cc1:TBoxBaseCTL

I don't know what it is. I would consider commenting out your current on text changed code stub, and typing in the event name in the markup, and letting IntelliSense create the event stub for you (how this is done is shown above for the custom event we have, and this results in a event stub without the "handles" included in the server behind code). So, some details here are missing in regards to the actual type of control you are using, but it's not a standard textbox.