hello i am trying to pass parameters from asp LinkButton to a sub routine and it doesn't work
this is the linkbutton
<asp:LinkButton runat="server" ID="linkId" OnClick="doSomething(10)">ID
</asp:LinkButton>
and this is my sub
Public Sub doSomething(ByVal mon As Integer)
MsgBox("this is the number : " & mon)
End Sub
can some one tell me how can we make this work in VB.net
Try with CommandArgument property
<asp:LinkButton runat="server" ID="linkId" OnClick="doSomething"
CommandArgument="10">ID</asp:LinkButton>
and
Public Sub doSomething(sender As Object, e As EventArgs)
Dim btn As LinkButton = DirectCast(sender, LinkButton )
Dim msg As String = "this is the number : " & Int32.Parse(btn.CommandArgument)
End Sub
You cannot pass anything directly to an event handler. But you can use LinkButton's CommandArgument property:
<asp:LinkButton runat="server"
ID="linkId"
OnClick="LinkButton_Click"
CommandArgument="10">ID
</asp:LinkButton>
in your codebehind (with the correct signature for this event):
Protected Sub LinkButton_Click(sender As Object, e As EventArgs)
Dim lb = DirectCast(sender, LinkButton)
Dim ID As String = lb.CommandArgument;
End Sub
Note that you should not use a MessageBox in an ASP.NET environment since it would be shown on the server and not in the browser.
You don't have to use the DirectCast method. It may make more sense for your sub to look like this:
Public Sub doSomething(sender As Object, e As CommandEventArgs)
Dim msg As String = "this is the number : " & e.CommandArgument
End Sub
You can also store a second value in the CommandName property of the control and use it the same way.
edit: With a slight change to your control, use OnCommand instead of OnClick:
<asp:LinkButton runat="server" ID="linkId" OnCommand="doSomething"
CommandArgument="10" Text="ID" />
Related
I can't seem to find anything related to the problem I'm encountering.
GOAL
I'm trying to get the value of a custom data attribute from the button (Web Control) that I created in my code-behind when the button is clicked. I'm referencing MSDN-Attribute.GetCustomAttribute Method but I'm not sure if this is appropriate for what I'm trying to do.
My current click sub is below but does not function.
Default.ascx
<asp:UpdatePanel ID="itemWrapper" UpdateMode="Conditional" runat="server">
<ContentTemplate>
<asp:PlaceHolder ID="itemsPlaceholder" runat="server" />
</ContentTemplate>
</asp:UpdatePanel>
Default.ascx.vb (Code-behind)
Protected Sub Items_Load()
Dim dynamicID = "13"
Dim itemBtn = New Button()
itemBtn.Attributes.Add("data-custom-id", dynamicID) '<- Custom attribute I want to get
itemBtn.UseSubmitBehavior = False
itemBtn.Text = "select"
itemBtn.ID = "Button_" & dynamicID
AddHandler itemBtn.Click, AddressOf ItemSelectBtn_Click
itemsPlaceholder.Controls.Add(itemBtn)
End Sub
Public Sub ItemSelectBtn_Click(ByVal sender As Object, ByVal e As EventArgs)
Dim clickedBtn = DirectCast(sender, Button),
clickedBtnID As String = clickedBtn.Attributes("data-custom-id")
Console.WriteLine("this button's ID is " & clickedBtnID)
End Sub
HTML OUTPUT
<div id="Content_C001_itemWrapper">
<input type="button"
name="ctl00$Content$C001$1"
value="select"
onclick="target = '_blank';__doPostBack('ctl00$Content$C001$1','')"
data-custom-id="13">
</div>
UPDATE
This was the simplest answer. Not sure why this wasn't working but as #zgood suggested to get the attribute. VB.NET uses Attributes("attribute-name") and not Attributes["attribute-name"] like in C#. Just an FYI.
Thanks for the help!
The label lblTempLib in the Form has the data coming from table A. This needs to be passed on to the dropdown list as the selected value to datasource in the edit template.
This is the object datasource for LibDS (markup):
SelectCommand="SELECT [LibName] FROM [tblBuilding]"></asp:SqlDataSource>
<asp:FormView ID="frmUpdateIncident" runat="server" DataSourceID="InciDetailDS" OnDataBound="frmUpdateIncident_DataBound">
<EditItemTemplate>
<asp:Label runat="server" ID="lblLib" Text="Library:" CssClass="style_bold"></asp:Label><br />
<asp:Label ID="lblTempLib" runat="server" Text='<%# Eval("Library")%>'Visible="true"></asp:Label>
<asp:Dropdownlist runat="server" ID="ddLib" DataTextField="LibName" DataSourceID="LibDS" >
</asp:Dropdownlist>
VB.NET code:
Protected Sub frmUpdateIncident_DataBound(sender As Object, e As EventArgs) Handles frmUpdateIncident.DataBound
Dim ddLib As DropDownList
Try
If Page.FindControl("ddLibrary") IsNot Nothing Then
ddLib = DirectCast(frmUpdateIncident.FindControl("ddLibrary"), DropDownList)
ddLib.Items.FindByText(strLibName).Selected = True
End If
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
Ok, I finally got it. Need to pass the index value to the dropdown SelectedIndex value as this property can get and set the value unlike SelectedValue.
strLibName is the value passed on by the previous form.
I hardcoded ddLib.SelectedIndex in here to test it but I will be fixing it by passing the list index value.
VB.Net Code:
Protected Sub frmUpdateIncident_DataBound(sender As Object, e As EventArgs) Handles frmUpdateIncident.DataBound
If frmUpdateIncident.CurrentMode = FormViewMode.Edit Then
Dim ddlib As DropDownList
ddlib = DirectCast(frmUpdateIncident.FindControl("ddLibrary"), DropDownList)
If ddLib IsNot Nothing Then
If ddLib.Items.Count > 0 Then
If strLibName IsNot Nothing Then
ddlib.SelectedIndex = 2
Dim strtest As String = ddlib.SelectedValue.Trim
End If
End If
End If
End If
End Sub
I have a dropdownlist inside the gridview. Now i want when i click on a button then i can check the value of dropdownlist. I have fired rowcommand event of gridview for it but debugger is not able to go reach there..Please help me..My Code is
Protected Sub grd_Test_RowCommand(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewCommandEventArgs) Handles grd_Test.RowCommand
If e.CommandName = "Select" Then
End If
End Sub
my Source code is
<asp:GridView ID="grd_UnAssignProperties" runat="server" AutoGenerateColumns="False"><Columns>
<asp:TemplateField HeaderText="Assign To">
<ItemTemplate>
<asp:DropDownList ID="drp_UnAssignProp" runat="server">
<asp:ListItem Value="" >Default</asp:ListItem>
</asp:DropDownList>
</ItemTemplate>
</asp:TemplateField>
</Columns></asp:GridView><tr><td><asp:Button ID="btn_Save" runat="server" CommandName="Select" Text="Submit" />
try this
DropDownList ddl = (DropDownList)GridView1.Rows[e.RowIndex].Cells[0].FindControl("drp_UnAssignProp");
string val = ddl.SelectedValue;
try
string val = (DropDownList)GridView1.Rows[e.RowIndex].Cells[0]
.FindControl("drp_UnAssignProp").SelectedValue;
First of all, since the button btn_Save isn't inside the GridView, clicking on it won't raise the grd_Test_RowCommand, either move the button inside GridView or you have to raise it manually like this:
Copied from asp.net forum:
Protected Sub Button1_Click(sender As Object, e As EventArgs)
Dim commandArgs As New CommandEventArgs("Command Name Here", "Your Command Argument Here")
'You can pass any row
'You can also skip the row parameter and get the row from Command Argument
Dim eventArgs As New GridViewCommandEventArgs(GridView1.Rows(0), GridView1, commandArgs)
GridView1_RowCommand(GridView1, eventArgs)
End Sub
Now regarding your original question, this is how you can get the selected value of DropDownList inside RowCommand event:
Edit: Fixed code to get the current row, for which the RowCommand event was raised
Protected Sub grd_Test_RowCommand(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewCommandEventArgs) Handles grd_Test.RowCommand
If e.CommandName = "Select" Then
Dim index As Integer = Convert.ToInt32(e.CommandArgument)
Dim row As GridViewRow = DirectCast(DirectCast(e.CommandSource, LinkButton).NamingContainer, GridViewRow)
Dim ddl as DropDownList = CType(row.FindControl("drp_UnAssignProp", DropDownList)
Dim selectedValue as String = ddl.Text
End If
End Sub
I'm trying to make a tabbed menu for the asp.net website I'm working on. One of the pre-requisite is obviously to color the current tab differently, so the user can know on which tab is currently is.
To do this, I made this method in my code-behind:
Protected Function GetCssClass(ByVal ctrl As LinkButton) As String
If ctrl.ID = currentLink Then
Return "current"
Else
Return String.Empty
End If
End Function
and I call the method like this in my aspx page:
<asp:LinkButton ID="LinkButton1" runat="server" PostBackUrl="/Default.aspx" CssClass="<%#GetCssClass(LinkButton1) %>" >Home</asp:LinkButton>
<asp:LinkButton ID="LinkButton2" runat="server" PostBackUrl="/Directory/page1.aspx" CssClass="<%#GetCssClass(LinkButton2) %>" >Page1</asp:LinkButton>
But the method is never hit... As I understand, the method should be called each time the LinkButton is drawn...
Does someone have an idea why?
Thanks in advance !
Edit: Just as a precision, all this code is in the masterpage.
Edit2: Here are the changes I made according to Quagland's suggestion.
In the aspx masterpage:
<asp:HiddenField ID="currentLink" runat="server" />
<asp:LinkButton ID="LinkButton1" runat="server" PostBackUrl="/Default.aspx" OnClick="LinkButton_Click" OnPreRender="LinkButton_PreRender" >Home</asp:LinkButton>
<asp:LinkButton ID="LinkButton2" runat="server" PostBackUrl="/OtherDirectory/Page1.aspx" OnClick="LinkButton_Click" OnPreRender="LinkButton_PreRender" >Page1</asp:LinkButton>
<asp:LinkButton ID="LinkButton3" runat="server" PostBackUrl="/OtherDirectory/Page2.aspx" OnClick="LinkButton_Click" OnPreRender="LinkButton_PreRender" >Page2</asp:LinkButton>
<asp:LinkButton ID="LinkButton4" runat="server" PostBackUrl="/OtherDirectory/Page3.aspx" OnClick="LinkButton_Click" OnPreRender="LinkButton_PreRender" >Page3</asp:LinkButton>
And in the code behind:
Protected Sub LinkButton_Click(ByVal sender As Object, ByVal e As EventArgs) Handles LinkButton1.Click, LinkButton2.Click, LinkButton3.Click, LinkButton4.Click, LinkButton5.Click, LinkButton6.Click, LinkButton7.Click, LinkButton8.Click
Dim lnk As LinkButton = CType(sender, LinkButton)
currentLink.Value = lnk.ID
End Sub
Protected Function GetCssClass(ByVal ctrl As LinkButton) As String
If ctrl.ID = currentLink.Value Then
Return "current"
Else
Return String.Empty
End If
End Function
Protected Sub LinkButton_PreRender(ByVal sender As Object, ByVal e As EventArgs) Handles LinkButton1.PreRender, LinkButton2.PreRender, LinkButton3.PreRender, LinkButton4.PreRender, LinkButton5.PreRender, LinkButton6.PreRender, LinkButton7.PreRender, LinkButton8.PreRender
Dim lnk As LinkButton = CType(sender, LinkButton)
lnk.CssClass = GetCssClass(lnk)
End Sub
The problem is now that the click event is not always fired. On first click, nothing happens, but on second click on a tab, the click event is correctly triggered. Any clue ?
Edit3: Could it be that the value stored in the hidden field is reset each time the masterpage is reloaded (I mean, each link points to a couple masterpage + content page) ?
You need to use <%= ... %> (i.e. replace # with =).
The hash form is used with data binding, you want to just create output.
For .NET 4 prefer <%: ... %> (use a colon) to automatically do HTML encoding.
I have quickly tested a solution that might work for you. I'm just not sure where your 'currentlink' variable comes from. I have implemented it as a hidden field here.
In Masterpage.aspx:
<asp:HiddenField ID="currentLink" runat="server" />
<asp:LinkButton ID="LinkButton1" runat="server">Home</asp:LinkButton>
<asp:LinkButton ID="LinkButton2" runat="server">Page1</asp:LinkButton>
In code behind:
use your original GetCssClass function add this:
Protected Sub LinkButton_PreRender(ByVal sender As Object, ByVal e As System.EventArgs)
Handles LinkButton1.PreRender, LinkButton2.PreRender
Dim lnk As LinkButton = CType(sender, LinkButton)
lnk.CssClass = GetCssClass(lnk)
End Sub
I have put it in PreRender because i was using the LinkButton click events to set the hidden field value (and Click happens after Load but before PreRender):
Protected Sub LinkButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) _
Handles LinkButton1.Click, LinkButton2.Click
Dim lnk As LinkButton = CType(sender, LinkButton)
currentLink.Value = lnk.ID
End Sub
also, if there are numerous Linkbuttons, you may want to declare like:
<asp:LinkButton ID="LinkButton1" runat="server" OnClick="LinkButton_Click" OnPreRender="LinkButton_PreRender">Home</asp:LinkButton>
EDIT:
Here is another solution that will work with cross page postbacks. Not much code but you'll need to put some on every page. Anyway:
Masterpage.aspx:
<asp:LinkButton ID="LinkButton1" runat="server" PostBackUrl="Default.aspx">Home</asp:LinkButton>
<asp:LinkButton ID="LinkButton2" runat="server" PostBackUrl="Page1.aspx">Page1</asp:LinkButton>
<asp:LinkButton ID="LinkButton3" runat="server" PostBackUrl="Page2.aspx">Page2</asp:LinkButton>
<asp:LinkButton ID="LinkButton4" runat="server" PostBackUrl="Page3.aspx">Page3</asp:LinkButton>
Masterpage.aspx.vb:
Public Sub SetCssClass(ByVal ctrl As String)
CType(FindControl(ctrl), LinkButton).CssClass = "current"
End Sub
All content pages:
*.aspx:
add this directive to create a strongly typed reference to the masterpage
<%# MasterType VirtualPath="~/MasterPage.master" %>
*.aspx.vb:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Master.SetCssClass("LinkButton1") '' << put the name of the relevant link button here
End Sub
Set the CssClass in the code-behind. This will state your intent more clearly than calling DataBind on your linkbuttons if you use databinding syntax. Since you're doing it for multiple controls maybe stick them in a method called ApplyCssClasses.
I'm not sure why <%= %> isn't working but personally I don't like to mix code and markup, I like to keep them completely separate.
I would suggest setting the CSS class in code perhaps on the page load event.
lnkPopulate.CssClass = "current"
<%# ... %> will work if you're OK with doing LinkButton1.DataBind() in your code-behind at the appropriate time.
I'm trying to figure out the best way to achieve this:
I need to show a drop down list when the page loads, the default selected value is nothing, or an empty element (such as "-"). When the user selects one value from the list, another drop down list is added below the first one, and so on.
My problem with this is how you make the page to remember the drop down lists created through postbacks and the values they have selected? Do I have to use some kind of array to store them or something?
Thank you very much.
EDIT: I did this example for dynamically add drop down lists and suscribe them to an event handler but the event won't fire.
EDIT 2: Changed the code because I labelled for VB.Net and posted something in C#. I update the code with some trivial improvements, but still won't fire the event :(
Private myDdlArray As New List(Of DropDownList)
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If (Session("ddl") Is Nothing) Then
Session("ddl") = myDdlArray
End If
If (Session("ddlcount") Is Nothing) Then
Session("ddlcount") = 0
End If
myDdlArray = CType(Session("ddl"), List(Of DropDownList))
Dim myDdl As New DropDownList
myDdl = New DropDownList
For Each myDdl In myDdlArray
panel.Controls.Add(myDdl)
panel.Controls.Add(New LiteralControl("<br/>"))
Next
Session("ddl") = myDdlArray
End Sub
Protected Sub btn_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btn.Click
myDdlArray = CType(Session("ddl"), List(Of DropDownList))
Dim ddlCount As Integer = CInt(Session("ddlcount")) + 1
Dim newDdl As New DropDownList
newDdl.ID = String.Format("ddlNPKMaterial{0}", ddlCount)
newDdl.AutoPostBack = True
AddHandler newDdl.SelectedIndexChanged, AddressOf cbo_SelectedIndexChanged
newDdl.Items.Add("Uno")
newDdl.Items.Add("Dos")
newDdl.Items.Add("Tres")
myDdlArray.Add(newDdl)
panel.Controls.Clear()
Dim myDdl As New DropDownList
myDdl = New DropDownList
For Each myDdl In myDdlArray
panel.Controls.Add(myDdl)
panel.Controls.Add(New LiteralControl("<br/>"))
Next
Session("ddl") = myDdlArray
Session("ddlcount") = ddlCount + 1
End Sub
Protected Sub btnReset_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnReset.Click
Session("ddl") = Nothing
Session("ddlcount") = Nothing
End Sub
Protected Sub btnShow_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnShow.Click
' Insert brain here
End Sub
Public Sub cbo_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)
Response.Write(CType(sender, DropDownList).ID)
End Sub
Protected Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreRender
If (Session("ddl") Is Nothing) Then
panel.Controls.Clear()
End If
End Sub
in the aspx I have:
<form id="form1" runat="server">
<div>
<asp:Button ID="btn" runat="server" Text="Add" />
<asp:Button runat="server" ID="btnShow" Text="Tell me" />
<asp:Button runat="server" ID="btnReset" Text="Reset" />
<br />
<asp:Panel runat="server" ID="panel">
<asp:GridView runat="server" ID="grd">
<Columns>
<asp:BoundField HeaderText="Id" DataField="Id" />
</Columns>
</asp:GridView>
</asp:Panel>
</div>
</form>
I'll use OnLoad to recreate the controls, but if you're not storing the # of controls in ViewState (you could put it into Session, a HiddenField, Cookie, etc.) then you can do it in OnInit. Either way should still fire the postback event.
<asp:PlaceHolder id="phDdl" runat="server">
<asp:DropDwonList id="ddl" runat="server"
OnSelectedIndexChanged="ddl_SelectedIndexChanged" />
</asp:PlaceHolder>
<script runat="server">
int DdlIndex {
get {
object o = ViewState["_ddlIndex"];
if (o == null) {
ViewState["_ddlIndex"] = 0;
}
return (int)ViewState["_ddlIndex"];
}
set {
ViewState["_ddlIndex"] = value;
}
}
protected override void OnLoad(EventArgs e) {
base.OnLoad(e);
for (int i = 0; i < DdlIndex; i++) {
AddDropDownList(i);
}
}
void ddl_SelectedIndexChanged(object sender, EventArgs e) {
var ddl = (DropDownList)sender;
if (ddl.SelectedIndex > 0) {
AddDropDownList(DdlIndex++);
}
}
void AddDropDownList(int i) {
var ddl = new DropDownList();
ddl.Id = string.Format("ddl{0}", i);
ddl.SelectedIndexChanged += ddl_SelectedIndexChanged;
// add items
phDdls.Add(ddl);
}
</script>
You can simply have both dropdown lists exist in your asp code with only one visible on first page load. So something like...
<asp:DropDownList ID="mainDDL" Visible="true" runat="server">
<asp:ListItem Text="Elements here" Value="0" />
<asp:ListItem Text="More elements" Value="1" />
</asp:DropDownList>
<asp:DropDownList ID="dynamicDDL" Visible="false" runat="server">
<asp:ListItem Text="This is an element of the dynamic DDL" Value="3" />
</asp:DropDownList>
And then when, say the "More Elements" item selected, switch the dynamicDDL's visibility to true.
Then on each postback, on the Page_Load event, check what the value of mainDDL is. If it is 0, set dynamicDDL to have visible=true
Edit:
Okay, I took a stab at this. There is some headway in this, however, and maybe it will lead us to some clues.
To start off, we DO need an array to store this. We will need a static array of DDLs and a static integer to count our elements. These can be defined as...
Private Shared ddl_arr As DropDownList() = New DropDownList(100) {} 'max, 100 ddls.
Private Shared ddl_count As Integer = 0
Now, we'll need a panel to store our DDLs in. This is simple asp scripting, such as...
<asp:Panel ID="parentPanel" runat="server">
<asp:DropDownList ID="mainDDL" AutoPostBack="true" Visible="true" runat="server">
<asp:ListItem Text="Elements here" Value="0" />
<asp:ListItem Text="More elements" Value="1" />
</asp:DropDownList>
</asp:Panel>
So now, on our page load we will want to load any of our dropdowns that we have saved so far. This can be coded in a way such as..
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Try
If TypeOf ddl_arr(0) Is DropDownList Then
For Each ddl As DropDownList In ddl_arr
add_ddl(ddl)
Next
End If
Catch ex As Exception ' this is a bad idea, but for brevity..
End Try
End Sub
Our add_ddl method will simply add our new drop down to the parentPanel.
Protected Sub add_ddl(ByVal ddl As DropDownList)
Try
parentPanel.Controls.Add(ddl)
'add any formatting you would like after each ddl here.
Catch ex As Exception
End Try
End Sub
And finally, our method when we change the ddl. This creates a brand new ddl, gives it an id (and whatever properties you may want for it), adds it to the array, increments our counter, and adds it to the page..
Protected Sub mainDDL_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles mainDDL.SelectedIndexChanged
Dim newDDL As DropDownList = New DropDownList()
newDDL.ID = "ddlID" & ddl_count 'we will need to store a new ID for each one. So, dynamically generate this.
'continue to add properties to your ddl in this fashion...
ddl_arr(ddl_count) = newDDL
ddl_count = ddl_count + 1
add_ddl(newDDL)
End Sub
This method should definitely check for the end of the array (among other things), but lets keep things simple. This code will only add a new DDL whenever you change the index of the ORIGINAL DDL. You will need to set each newly created DDL to have a method called (performing the above instructions) whenever the selected index changes for all of those newly crafted DDLs.
Hopefully this gets you in the right direction. This was way less organized than I'd hoped, sorry!
Dynamic controls are pretty tricky to create. I would start by reading this.
Create and add the dropdowns during the Page_Init method and generate the names based on the backing data that you're gathering. When getting input from them, either read their returned values off of the page using the FindControl() method or by getting the returned value of the control from the Request.Form[]. FindControl uses the id of the control, and Requst.Name uses the client id - you can get this information using the same function you use to generate the names.
Overall, ASP.NET isn't very good at working with generated controls, but by keeping the data you're working with in a model or datastructure separate from the controls that are being generated it isn't difficult to both create the controls and retrieve the results.