I have the following code in my aspx page:
<asp:Literal ID="ltPost" runat="server"></asp:Literal>
and this in my code behind:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack) {
BindData();
}
}
protected void BindData() {
str.Append(#"<asp:Button ID=*btnEditReply* runat=*server* CssClass=*button-action m-r-5* Text=*Sửa phản hồi* ValidationGroup=*AddSave*/>");
ltPost.Text = str.ToString().TrimEnd(',').Replace('*', '"');
}
I don't understand this; Why won't the button btnEditReply display?
To add a server control, you have to use Controls.Add(). Also, you can't add a button to a literal, so it's better to use a Placeholder.
C#:
Button editButton = new Button();
editButton.ID = "btnEditReply";
editbutton.Text = "Sửa phản hồi";
// .. etc
placeHolder.Controls.Add(editButton);
HTML:
<asp:Placeholder id="placeHolder" runat="server" />
Reference: http://msdn.microsoft.com/en-us/library/kyt0fzt1(v=vs.100).aspx
Related
I have a formular with dynamic data and UC.
my ascx file looks like:
<asp:Repeater ID="rMyData" runat="server" OnItemDataBound="OnRepeaterItemDataBound">
<ItemTemplate>
<asp:Panel ID="panelAdditional" runat="server"/>
</ItemTemplate>
</asp:Repeater>
and the cs file:
public partial class MyFormular
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
PrepareList();
DataBind();
}
}
private void PrepareList()
{
rMyData.DataSource = GetData();
rMyData.DataBind();
}
protected void OnRepeaterItemDataBound(object sender, RepeaterItemEventArgs e)
{
RepeaterItem repeaterItem = e.Item;
Panel panel = (Panel)repeaterItem.FindControl("panelAdditional");
if (panel != null)
{
var datarow= (Data)repeaterItem.DataItem;
if (datarow!= null)
{
panel.Controls.Clear();
MyUC ctrl;
ctrl = (MyUC)Page.LoadControl("~/MyUC.ascx");
ctrl.Enabled = true;
ctrl.DataRow = datarow;
panel.Controls.Add(ctrl);
}
}
}
protected void SaveNewsletterSubscription(object sender, EventArgs e)
{
...
}
}
My problem is, it doesn't show my UC.
If I put my PrepareList() and DataBind() outside of the PostBack, it works perfectly fine and shows my UC. But after I press the save Button, it reloads the page and rebind my repeater. So I lost everything in the UC.
Why does it only show my UC if I rebind it in every pageload?
I hope the I posted enough information.
I have a textbox and submit button created using the design mode.
When the submit button is pressed, it will retrieve the user input from the textbox and then make a query to my database.
It will then display a list of dynamic buttons according to the information retrieved from my database.
However, the event handler for the buttons does not fire when clicked. I guess my problem is the postback but I cannot create those buttons in page_load etc. because I need to get the user input (from the textbox when submit button is pressed) before i can load the buttons.
How can i solve this problem?
Thank you.
Edit (codes):
protected void subBtn_Click(object sender, EventArgs e)
{
//database setup codes
.......
while (reader.Read())
{
Button detailsBtn = new Button();
detailsBtn.Text = reader["fName"].ToString();
//doesn't fire
detailsBtn.Click += new EventHandler(detailsBtn_Click);
memPanel.Controls.Add(detailsBtn);
}
}
Main problem is Postback regenerate dynamic controls on each postback if those controls does not exists.
For quick demo see this code
ASPX CODE
<form id="form1" runat="server">
<asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />
<asp:Panel ID="pnl" runat="server"></asp:Panel>
</form>
ASPX.CS CODE
protected void Page_Load(object sender, EventArgs e)
{
if(IsPostBack)
{
generate();
}
}
public void generate()
{
if (!pnl.HasControls())
{
for (int i = 0; i < 4; i++)
{
Button detailsBtn = new Button();
detailsBtn.Text = "fName" + i.ToString();
detailsBtn.ID = i.ToString();
detailsBtn.Click += new EventHandler(detailsBtn_Click);
pnl.Controls.Add(detailsBtn);
}
}
}
protected void Button1_Click(object sender, EventArgs e)
{
generate();
}
protected void detailsBtn_Click(object sender, EventArgs e)
{
}
Sound to me like you could easily refactor your page to use a simple <asp:Repeater runat="server" ..></asp:Repeater> instead of dynamically adding controls to a Panel.
Here is a very simple complete sample:
RepeaterTest.aspx
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="Server">
<asp:TextBox ID="theTextBox" runat="server"></asp:TextBox>
<asp:Button ID="theButton" runat="server" OnClick="theButton_Click" Text="Click me" />
<asp:Repeater ID="test" runat="server">
<ItemTemplate>
<asp:Button ID="theRepeaterButton" runat="server" Text='<%# Eval("fName") %>' OnClick="theRepeaterButton_Click" />
</ItemTemplate>
</asp:Repeater>
</asp:Content>
RepeaterTest.aspx.cs
public partial class RepeaterTest : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void theButton_Click(object sender, EventArgs e)
{
string filter = theTextBox.Text;
// below row simulates fetching data using the filter text in the text box
var data = Enumerable.Range(0, 20).Select(i => new { fName = filter + " " + i });
test.DataSource = data;
test.DataBind();
}
protected void theRepeaterButton_Click(object sender, EventArgs e)
{
var button = (Button)sender;
// do something here based on text/commandname/commandargument etc of the button
}
}
I have an item template within repeater:
<ItemTemplate>
<li>
<input type="radio"
value="<%# GetAssetId((Guid) (Container.DataItem)) %>"
name="AssetId"
<%# SelectAsset((Guid) Container.DataItem) %> />
</li>
</ItemTemplate>
I have a method that compares ids and decides whether to check the radio button.
protected string SelectAsset(Guid uniqueId)
{
if (uniqueId == GetSomeId())
return "checked=\"checked\"";
return string.Empty;
}
SelectAsset gets hit, but it doesn't select a radio button on a post back, but it does work if I just refresh the page. What am I doing wrong here?
Answer here: How to display "selected radio button" after refresh? says that it's not possible to achieve, is this really the case?
Thank you
Update
It appears that view state isn't available for simple controls if they don't have a runat attribute. I have solved this by using a custom GroupRadioButton control. Thank you for your help.
I'd suggest using a RadioButtonList:
Page Code
<asp:RadioButtonList RepeatLayout="UnorderedList" OnSelectedIndexChanged="IndexChanged" AutoPostBack="true" ID="RadioRepeater" runat="server" />
<asp:Label ID="SelectedRadioLabel" runat="server" />
Code Behind
if (!Page.IsPostBack)
{
/* example adds items manually
- you could iterate your datasource here as well */
this.RadioRepeater.Items.Add(new ListItem("Foo"));
this.RadioRepeater.Items.Add(new ListItem("Bar"));
this.RadioRepeater.Items.Add(new ListItem("Baz"));
this.RadioRepeater.SelectedIndex = this.RadioRepeater.Items.IndexOf(new ListItem("Bar"));
this.RadioRepeater.DataBind();
}
protected void IndexChanged(object sender, EventArgs e)
{
this.SelectedRadioLabel.Text = string.Format("Selected Item Text: {0}", this.RadioRepeater.SelectedItem.Text);
}
I assume you only need to select one item.
As described in the comments, it even works to access the SelectedItem in the Page_Loadevent handler:
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
// previous code omitted
}
else
{
string foo = this.RadioRepeater.SelectedItem.Text;
}
}
If you are creating all your controls dynamically at run-time (directly from code), then things are a little different. Here is the code that I used:
Page Code
<form id="form1" runat="server">
</form>
Code Behind
protected void Page_Load(object sender, EventArgs e)
{
RadioButtonList rbl = new RadioButtonList();
rbl.AutoPostBack = true;
rbl.SelectedIndexChanged += rbl_SelectedIndexChanged;
rbl.Items.Add("All");
// generate your dynamic radio buttons here
for (int i = 0; i<5; i++)
{
rbl.Items.Add(string.Format("Dynamic{0}", i));
}
form1.Controls.Add(rbl);
if (!Page.IsPostBack)
{
rbl.SelectedValue = "All";
PopulateTextBox(rbl.SelectedValue);
}
}
void rbl_SelectedIndexChanged(object sender, EventArgs e)
{
RadioButtonList foo = (RadioButtonList)sender;
PopulateTextBox(foo.SelectedValue);
}
void PopulateTextBox(string selection)
{
TextBox box = new TextBox();
box.Text = selection;
form1.Controls.Add(box);
}
I have this html.
<a id="a1" runat=server>
I want to add event handler to this <a> tag using code behind.
If a user press this tag, it should cause an event on the server-side.
For an easy solution there is the linkbutton on the toolbox which shows as a link but reacts as a button.
I'm not sure what you are trying to accomplish, but it seems that you want something like this:
On the .ASPX page
<asp:LinkButton ID="myLinkButton" OnClick="myLinkButton_Click" runat="server"></asp:LinkButton>
In the .ASPX.CS
protected void Page_Load(object sender, EventArgs e)
{
myLinkButton.CommandArgument = "1";
}
protected void myLinkButton_Click(object sender, EventArgs e)
{
int myLinkButtonID = Convert.ToInt32(((LinkButton)sender).CommandArgument);
}
Try this,
Html Tag:
<a id="a1" runat="server">
Code Behind:
protected void Page_Init(object sender, EventArgs e)
{
a1.ServerClick += new EventHandler(a1_ServerClick);
}
protected void a1_ServerClick(object sender, EventArgs e)
{
//Your Code here....
}
This will Create a Click Event for the <a> tag.
I am trying to set a ViewState-variable when a button is pressed, but it only works the second time I click the button. Here is the code-behind:
protected void Page_Load(object sender, EventArgs e)
{
if (Page.IsPostBack)
{
lblInfo.InnerText = String.Format("Hello {0} at {1}!", YourName, DateTime.Now.ToLongTimeString());
}
}
private string YourName
{
get { return (string)ViewState["YourName"]; }
set { ViewState["YourName"] = value; }
}
protected void btnSubmit_Click(object sender, EventArgs e)
{
YourName = txtName.Text;
}
Is there something I am missing? Here is the form-part of the design-file, very basic just as a POC:
<form id="form1" runat="server">
<div>
Enter your name: <asp:TextBox runat="server" ID="txtName"></asp:TextBox>
<asp:Button runat="server" ID="btnSubmit" Text="OK" onclick="btnSubmit_Click" />
<hr />
<label id="lblInfo" runat="server"></label>
</div>
</form>
PS: The sample is very simplified, "use txtName.Text instead of ViewState" is not the correct answer, I need the info to be in ViewState.
Page_Load fires before btnSubmit_Click.
If you want to do something after your postback events have fired use Page_PreRender.
//this will work because YourName has now been set by the click event
protected void Page_PreRender(object sender, EventArgs e)
{
if (Page.IsPostBack)
lblInfo.InnerText = String.Format("Hello {0} at {1}!", YourName, DateTime.Now.ToLongTimeString());
}
The basic order goes:
Page init fires (init cannot access ViewState)
ViewState is read
Page load fires
Any events fire
PreRender fires
Page renders