i am trying to retain the value of a variable from a previous page. i believe this is the C# way to do this, but i would like the vb.net way can someone please help:
TextBox myTxt = (TextBox)Page.PreviousPage.FindControl("previousPageTextBox");
currentPageTextBox.text = myTxt.Text;
i would like to know how to code this in vb.net
i tried this:
Dim myTxt As TextBox = CType(Page.PreviousPage.FindControl("Textbox1"), TextBox)
TextBox1.Text = myTxt.Text
but i got this error msg:
use the new keyword to create an object instance
This should do it, also make sure you are using Server.Transfer to go between pages.. but I am sure you already know this:
Dim myTxt as TextBox = CType(Page.PreviousPage.FindControl("previousPageTextBox"), TextBox)
currentPageTextBox.text = myTxt.Text
dim txt as TextBox =CType( Page.PreviousPage.FindControl("previousPageTextBox"),
TextBox)
currentPageTextBox.Text = txt.Text
PS:- You need to set the previous page in the page where you want to find the control.
<%# PreviousPageType VirtualPath="~/Test.aspx" %>
Also better way will be to create an function on previous page which returns the text in textbox.
internal function TextBoxText() as string
return myTextPage.Text
end function
and use this on next page like this:
currentPageTextbox.Text = Page.PrevousPage.TextBoxText
let me know if this works because I've not used vb for long long time.
PPS:- It is only available if you user Server.Transfer or go to currentPage using some asp.net contorl like LinkButton from simple href links PreviousPage is null
Related
I am trying to pass a textbox value from one aspx page to another aspx page. I have tried - Previous page property and Application variable. I do not want to use cookies for this textbox. I have tried the below code in page 2 and it throws me "Object reference not set to an instance of an object." error.
Any help would be appreciated.
If Not IsNothing(Request.Cookies("IMF")("UserID")) Then
lblUserID.Text = (Request.Cookies("IMF")("UserID").ToString())
Dim txt As TextBox
txt = CType(Page.PreviousPage.FindControl("txtUsername"), TextBox)
If Not IsNothing(txt) Then
lblUserName.Text = Server.HtmlEncode(txt.Text)
Else
lblUserName.Text = "[Name Not available]"
End If
End If
How do I check for the existence of an item in a dropdownlist in vb.net?
Here's my not working code:
dim ddlTestDropdown as dropdownlist
ddlTestDropdown = New DropDownList()
If(ddlTestDropdown.Items.FindByValue("42") Is Not nothing)
Console.WriteLine("It's there")
End If
it won't let me compare the returned ListItem to nothing
Update: The error is from saying Is Not the fix is to say:
If(Not ddlTestDropdown.Items.FindByValue("42") Is Nothing)
Alternate answer:
Here's what I found to do this. Like #praythyus tried you need to test for contains, but vb.net only lets you do contains on a listitem. So I combined what I did with what he did and this worked:
Dim SetThisIfExists = ddlTestDropdown.Items.FindByValue("42")
If(ddlTestDropdown.Items.Contains(SetThisIfExists))
ddlTestDropdown.SelectedIndex = ddlTestDropdown.Items.IndexOf(SetThisIfExists)
End If
Sorry for giving C# syntax. Can you try with
as #RS said, you need to fill the ddl after initializing.
if(ddlTestDropdown.Items.Contains("42"))
{
}
Or instead of FindByValue can you use FindByText
I have an ASP project which references a WCF service. Does exactly half of what I need.
A button on the page calls a function from the WCF, which returns a list of objects (variable names). When returned, the vb code dynamically adds textboxes to a panel on the page. Like this:
For Each LetterVariables In LetterVarList
tb = New TextBox
lb = New Label
lb.Text = LetterVariables._key & " "
tb.ID = LetterVariables._key
pnlVars.Controls.Add(lb)
pnlVars.Controls.Add(tb)
Dim LineBreak As LiteralControl = New LiteralControl("<br />")
pnlVars.Controls.Add(LineBreak)
Next
Now the problem is, after this is finished the user will enter some values into those texboxes. I (somehow) need to reference those texboxes to snag the values when a user clicks another button.
How can I do this?
Thanks,
Jason
You can give the TextBox an ID which you could use FindControl to retrieve.
tb.ID = "txt" + LetterVariables._key.ToString();
Then when you want to reference it.
TextBox txtBox = (TextBox)FindControl("txt" + someKey);
Something like that might work for you.
Don't forget to recreate the controls on post back BEFORE the controls are loaded with the posted values.
I'm working with a website written in aspx.net over vb.
I have a placeHolder, and I create a table of names inside this PlaceHolder, each name has an HtmlInputCheckBox next to it.
Im doing this in the aspx.vb file, when the page is uploading.
Then, when the user wants to send mail, he presses a button and than I need to access the checkboxes, and I'm having problems with this, the Sub doesn't know the checkBox object.
I would love for some help,
Thank you!
I understand that you're creating those checkboxes dynamically?
In such case, store them as global member of the class, most simple way is to have List of them:
List<HtmlInputCheckBox> arrCheckboxes = new List<HtmlInputCheckBox>();
...
...
HtmlInputCheckBox myCheckbox = new HtmlInputCheckBox();
arrCheckboxes.Add(myCheckbox);
...
This is C# but should be easy to translate to VB - anyhow having this, you can access the List and it should work.
Worst case as "last resort" you can simply iterate the whole Request.Form collection and look for Keys with name matching to the checkbox name.
Put this in the procedure...
Dim chkValue1 As New CheckBox
Dim chkValue2 As New CheckBox
'Find the Checkbox Controls in the PlaceHolder and cast them to the checkboxes we just made.
chkValue1 = CType(YourPlaceHolder.FindControl("Checkbox1ControlId"), CheckBox)
chkValue2 = CType(YourPlaceHolder.FindControl("Checkbox2ControlId"), CheckBox)
'Now you can do this...
Dim bolIsValue1Checked As Boolean = chkValue1.Checked
I'm sure this question has been asked a million times, however I haven't been able to find an answer that solves my problem.
I am programmatically adding some custom user controls to a PlaceHolder which I have on a simple aspx page. All of the user controls Postback's work correctly except for one which has a Gridview on it.
For some reason any postback that gets fired from within this control, does not call the specified event on the first click, however all future clicks it will work fine. I have no idea why this is the case, but many solutions I have found, suggest adding an ID to the ascx User Control, however this doesn't work in my case.
I've taken a look at the source file for the page that gets generated before and after the first click, javascript used for calling the postback changes, i.e
Before first click: onclick="javascript:__doPostBack('tmpControlID$sgvPrimaryEmploymentHistory','Select$0')"
After first click: onclick="javascript:__doPostBack('OFFHome1$tmpControlID$sgvPrimaryEmploymentHistory','Select$0')"
OFFHome1 is the parent user control which exists on the aspx page. All other controls are added to a placeholder in this control, i.e.
<%# Control Language="vb" AutoEventWireup="false" CodeBehind="OFFHome.ascx.vb" Inherits="UmbracoUserControls.OFFHome" %>
<asp:PlaceHolder ID="phOFFSection" runat="server"></asp:PlaceHolder>
Nothing to complicated. Then in the code behind the controls are loaded into the placeholder using the following:
Private Sub LoadNextOFFStep()
Dim ControlName As String = "TestControl.ascx"
phOFFSection.Controls.Clear()
If ControlName IsNot Nothing AndAlso ControlName <> String.Empty Then
Dim NewControl As Object = LoadControl(ControlName)
With NewControl
.ID = USERCONTROLNAME
Dim StepCompleted As Boolean = .FillControl()
If StepCompleted Then
Exit Sub
End If
Dim AllowSkip As Boolean = .AllowSkip()
btnSkip.Visible = AllowSkip
End With
phOFFSection.Controls.Add(NewControl)
End If
End Sub
Again, nothing overly complicated. The USERCONTROLNAME is just a const with the value "tmpControlID" in it.
The control that is giving me trouble is a little complicated, I was originally using a custom GridView control that we have created, but have removed it and replaced it with the standard asp one to see if the problem still occurs, and it does.
Any button, on control which fires off a postback will fail the first time, and all future click will work correctly. On the first click the Page_Load event will get called, but that is it.
What am I doing wrong??
After far too much time spent on this, I have finally worked it out.
It was to do with the order of events, however just not where I had thought. The FillControl function was getting called before User Control had been added to the PlaceHolder. I changed this so that it gets called after the User Control was added to the PlaceHolder and now it works first time.
Basically the code looks like this now:
Private Sub LoadNextOFFStep()
Dim ControlName As String = "TestControl.ascx"
phOFFSection.Controls.Clear()
If ControlName IsNot Nothing AndAlso ControlName <> String.Empty Then
Dim NewControl As Object = LoadControl(ControlName)
With NewControl
.ID = USERCONTROLNAME
Dim AllowSkip As Boolean = .AllowSkip()
btnSkip.Visible = AllowSkip
End With
phOFFSection.Controls.Add(NewControl)
Dim StepCompleted As Boolean = CType(phOFFSection.Controls(0), Object).FillControl()
If StepCompleted Then
LoadNextOFFStep()
Exit Sub
End If
End If
End Sub
Thanks for everyone's help.
Well... the answer to the first question is simple: It fails the first time because the ID of the control (or rather, in the postback script) is different on subsequent page loads. It works on subsequent clicks because the control ID stays the same.
Now as to WHY that is... much tougher! But probably something to do with the order of operations here.
Try explicitly setting the NamingContainer value for NewControl:
With NewControl
.NamingContainer = OffHomeOne; // whatever
.ID = USERCONTROLNAME