We Keep Coding

Pass client id to code behind

Is there some way to pass the unique client id to codebehind? I have a imagebutton in a gridview and I wish to do something like this:
<asp:ImageButton ID="imbView" runat="server" ToolTip="View details" ImageUrl="~/css/images/View.png" CommandName="wView" CommandArgument='#<%=imbView.ClientID%>' />
On debugging though I see that my CommandArgument is #<%=imbView.ClientID%>..
To specify: I want to pass something that uniquely identifies generated elements (and I thought that the ClientID would be a good way to identify it).

Huh ?
Assuming you have
<asp:ImageButton ID="imbView" runat="server" ToolTip="View details" ImageUrl="~/css/images/View.png" CommandName="wView" OnCommand="aaa" />
then -
protected void aaa(object sender, CommandEventArgs e)
{
var a= (sender as Control).ClientID;
}

Here is how you retrieve CommandArgument inside RowCommand event.
You can also use e.CommandSource as ImageButton inside RowCommand event.
<asp:GridView ID="GridView1" runat="server"
AutoGenerateColumns="False"
OnRowCommand="GridView1_RowCommand">
<Columns>
<asp:TemplateField HeaderText="Detail">
<ItemTemplate>
<asp:ImageButton ID="imbView" runat="server"
ToolTip="View details" ImageUrl="~/css/images/View.png"
CommandName="wView"
CommandArgument='<%# Eval("Id") %>' />
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField HeaderText="Name" DataField="Name">
</asp:BoundField>
</Columns>
</asp:GridView>
Code Behind
public class Item
{
public int Id { get; set; }
public string Name { get; set; }
}
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
GridView1.DataSource = new List<Item>
{
new Item {Id = 1, Name = "John"},
new Item {Id = 2, Name = "Eric"},
};
GridView1.DataBind();
}
}
protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
{
if (e.CommandName == "wView")
{
var imageButton = e.CommandSource as ImageButton;
string clientId = imageButton.ClientID;
int id = Convert.ToInt32(e.CommandArgument);
}
}

Gridview click on row enable controls

I have a gridview. The gridview has a textbox multiline that keeps an text. After that I have a column with imagebutton named approved, and one named not approved. I want to force the user before click approved or not approved to read the text inside the multiline box. How can I achieve this programmatically? I know I should create a Rowdatabound Event, but what I should do with the code? I am using c# ASP.NET web application.

I know you can track the scroll bar of the browser using javascript but I've personally never come across similar functionality for a text box. I would suggest trying a slightly different approach, why don't you add an extra column to you grid view which has a check box control for - I've read and accepted the agreement. And the Approve button will only be enabledd when the checkbox is checked, here's an example:
ASPX:
<div>
<asp:ScriptManager ID="sm" runat="server" />
<asp:UpdatePanel ID="updatePanel" runat="server">
<ContentTemplate>
<asp:GridView ID="grid" runat="server" AutoGenerateColumns="false" OnRowDataBound="grid_RowDataBound">
<Columns>
<asp:TemplateField>
<ItemTemplate>
<asp:TextBox TextMode="MultiLine" runat="server" ID="txtAgreement" Text='<%# Eval("Agreement") %>' />
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
I have read and accepted the agreement
<asp:CheckBox ID="chkAgreement" AutoPostBack="true" runat="server" OnCheckedChanged="CheckedChanged" />
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
<asp:Button ID="btnAccept" runat="server" Text="Accept" OnClick="Accept" />
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
</ContentTemplate>
</asp:UpdatePanel>
</div>
Code behind:
public partial class Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
var items = new List<License> { new License { Agreement = "Agreement 1" }, new License { Agreement = "Agreement 2" } };
grid.DataSource = items;
grid.DataBind();
}
}
protected void Accept(object sender, EventArgs e)
{
}
protected void grid_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
(e.Row.FindControl("btnAccept") as Button).Enabled = false;
}
protected void CheckedChanged(object sender, EventArgs e)
{
var chkAgreement = sender as CheckBox;
Button btnAccept = null;
if (chkAgreement != null)
{
var row = chkAgreement.Parent.Parent as GridViewRow;
btnAccept = row.FindControl("btnAccept") as Button;
if (btnAccept != null)
if (chkAgreement.Checked)
btnAccept.Enabled = true;
else
btnAccept.Enabled = false;
}
}
}
public class License
{
public string Agreement { get; set; }
}

Dynamically added controls missing during GridView RowUpdating

I have a GridView with a TemplateField column that I put PlaceHolder controls in. During the DataBound event for the GridView I dynamically add a few CheckBoxes to the PlaceHolder. That works fine and displays as expected.
My problem is that during the RowUpdating event the PlaceHolder contains no controls; my CheckBoxes are missing. I also noticed that they're missing during the RowEditing event.
I want to be able to get the values of the CheckBoxes during the RowUpdating event so I can save them to the database.
Here's some example code. I've trimmed out a lot to reduce size, but if you want to see specifics just ask and I'll be happy to add more.
HTML:
<asp:GridView ID="gridView" runat="server" AutoGenerateColumns="False"
ondatabound="gridView_DataBound" onrowupdating="gridView_RowUpdating"
onrowediting="gridView_RowEditing" DataKeyNames="ID">
<Columns>
<asp:TemplateField HeaderText="Countries">
<ItemTemplate>
<asp:PlaceHolder ID="countriesPlaceHolder" runat="server"></asp:PlaceHolder>
</ItemTemplate>
<EditItemTemplate>
<asp:PlaceHolder ID="countriesPlaceHolder" runat="server"></asp:PlaceHolder>
</EditItemTemplate>
</asp:TemplateField>
<asp:TemplateField ShowHeader="False">
<ItemTemplate>
<asp:LinkButton ID="editButton" runat="server" CommandName="Edit" Text="Edit"></asp:LinkButton>
</ItemTemplate>
<EditItemTemplate>
<asp:LinkButton ID="updateButton" runat="server" CommandName="Update" Text="Update"></asp:LinkButton>
</EditItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
Code behind:
// This method works fine, no obvious problems here.
protected void gridView_DataBound(object sender, EventArgs e)
{
// Loop through the Holidays that are bound to the GridView
var holidays = (IEnumerable<Holiday>)gridView.DataSource;
for (int i = 0; i < holidays.Count(); i++)
{
// Get the row the Holiday is bound to
GridViewRow row = gridView.Rows[i];
// Get the PlaceHolder control
var placeHolder = (PlaceHolder)row.FindControl("countriesPlaceHolder");
// Create a CheckBox for each country and add it to the PlaceHolder
foreach (Country country in this.Countries)
{
bool isChecked = holidays.ElementAt(i).Countries.Any(item => item.ID == country.ID);
var countryCheckBox = new CheckBox
{
Checked = isChecked,
ID = country.Abbreviation + "CheckBox",
Text = country.Abbreviation
};
placeHolder.Controls.Add(countryCheckBox);
}
}
}
protected void gridView_RowEditing(object sender, GridViewEditEventArgs e)
{
// EXAMPLE: I'm expecting checkBoxControls to contain my CheckBoxes, but it's empty.
var checkBoxControls = gridView.Rows[e.NewEditIndex].FindControl("countriesPlaceHolder").Controls;
gridView.EditIndex = e.NewEditIndex;
BindData();
}
protected void gridView_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
// EXAMPLE: I'm expecting checkBoxControls to contain my CheckBoxes, but it's empty.
var checkBoxControls = ((PlaceHolder)gridView.Rows[e.RowIndex].FindControl("countriesPlaceHolder")).Controls;
// This is where I'd grab the values from the controls, create an entity, and save the entity to the database.
gridView.EditIndex = -1;
BindData();
}
This is the article that I followed for my data binding approach: http://www.aarongoldenthal.com/post/2009/04/19/Manually-Databinding-a-GridView.aspx

You need to call your BindData() method on page load.
"Dynamic controls or columns need to be recreated on every page load, because of the way that controls work. Dynamic controls do not get retained so you have to reload them on every page postback; however, viewstate will be retained for these controls."
See Cells in gridview lose controls on RowUpdating event
Also in the article you linked, there is an ItemTemplate and an EditItemTemplace because they have different displays, i.e. read only and editable. Yours are the same so I think you could simplify your design:
<asp:GridView ID="gridView" runat="server" AutoGenerateColumns="False" DataKeyNames="ID" ondatabound="gridView_DataBound">
<Columns>
<asp:TemplateField HeaderText="Countries">
<ItemTemplate>
<asp:PlaceHolder ID="countriesPlaceHolder" runat="server"></asp:PlaceHolder>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField ShowHeader="False">
<ItemTemplate>
<asp:LinkButton ID="editButton" runat="server" Text="Edit" onclick="editButton_Click" ></asp:LinkButton>
<asp:LinkButton ID="updateButton" runat="server" Text="Update" onclick="updateButton_Click" ></asp:LinkButton>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
Code Behind:
protected void gridView_DataBound(object sender, EventArgs e)
{
// Loop through the Holidays that are bound to the GridView
var holidays = (IEnumerable<Holiday>)gridView.DataSource;
for (int i = 0; i < holidays.Count(); i++)
{
// Get the row the Holiday is bound to
GridViewRow row = gridView.Rows[i];
// Get the PlaceHolder control
var placeHolder = (PlaceHolder) row.FindControl("countriesPlaceHolder");
var countryCheckBox = new CheckBox
{
Checked = true,
ID = "auCheckBox",
Text = "Aus",
Enabled = false
};
placeHolder.Controls.Add(countryCheckBox);
var editButton = (LinkButton)row.FindControl("editButton");
editButton.CommandArgument = i.ToString();
var updateButton = (LinkButton)row.FindControl("updateButton");
updateButton.CommandArgument = i.ToString();
updateButton.Visible = false;
}
}
protected void editButton_Click(object sender, EventArgs e)
{
LinkButton editButton = (LinkButton) sender;
int index = Convert.ToInt32(editButton.CommandArgument);
GridViewRow row = gridView.Rows[index];
// Get the PlaceHolder control
LinkButton updateButton = (LinkButton)row.FindControl("updateButton");
updateButton.Visible = true;
editButton.Visible = false;
CheckBox checkbox = (CheckBox)row.FindControl("auCheckBox");
if (checkbox != null)
{
checkbox.Enabled = true;
// Get value and update
}
}
protected void updateButton_Click(object sender, EventArgs e)
{
LinkButton updateButton = (LinkButton)sender;
int index = Convert.ToInt32(updateButton.CommandArgument);
GridViewRow row = gridView.Rows[index];
// Get the PlaceHolder control
LinkButton editButton = (LinkButton)row.FindControl("updateButton");
editButton.Visible = true;
updateButton.Visible = false;
CheckBox checkbox = (CheckBox)row.FindControl("auCheckBox");
if (checkbox != null)
{
// Get value and update
checkbox.Enabled = false;
}
}
If you want to be it enabled from the get go, just remove the enabled checks and you can delete your edit button.
Hope that helps.

Unable to cast object of type System.Web.UI.WebControls.GridView in ASP.NET

I wrote a method that deletes rows from my an asp.net Gridview when the delete button is clicked and another method for when the edit button is clicked.
Both Edit and Delete buttons are part of the built in gridview controls.
However when I press these buttons (edit/delete)and exception is thrown.
Unable to cast object of type 'System.Web.UI.WebControls.GridView' to type 'System.Web.UI.WebControls.Button'. which is pointing at the line
Button btn = (Button)sender;
The problem here is that this line is not related to either of the edit or delete methods. It is related to the asp button in another column, and for that reason I am lost. How can I resolve this issue? What is causing both the OnRowDeleting and OnRowEditing conflict with the showResponses method?
Here is the aspx
<asp:GridView runat="server" ID="gvShowQuestionnaires" HeaderStyle-CssClass="table_header" CssClass="view" AlternatingRowStyle-CssClass="alt" AlternatingRowStyle-BackColor="#f3f4f8" AutoGenerateColumns="False"
DataKeyNames='QuestionnaireID' OnRowDeleting="gvShowQuestionnaires_RowDeleting" OnRowEditing="gvShowQuestionnaires_RowEdit" FooterStyle-CssClass="view_table_footer" OnRowCommand="showResponses">
<Columns>
<asp:BoundField DataField="QuestionnaireID" HeaderText="ID" HeaderStyle-Width="80px" ItemStyle-CssClass="bo"></asp:BoundField>
<asp:BoundField DataField="QuestionnaireName" HeaderText="Questionnaire Name" />
<asp:TemplateField HeaderText="Results" HeaderStyle-Width="150px">
<ItemTemplate>
<asp:Button runat="server" ID="button1" CommandArgument='<%# Eval("QuestionnaireID") %>' OnClick="showResponses" text="Results"/>
</ItemTemplate>
</asp:TemplateField>
<asp:CommandField HeaderText="Options" ShowDeleteButton="True" ShowEditButton="true" EditText="Edit"></asp:CommandField>
</Columns>
</asp:GridView>
And here is the code behind:
protected void gvShowQuestionnaires_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
int questionnaireID = (int)gvShowQuestionnaires.DataKeys[Convert.ToInt32(e.RowIndex)].Value;
GetData.DeleteQuestionnaire(questionnaireID);
gvShowQuestionnaires.DataSource = DT;
gvShowQuestionnaires.DataBind();
}
protected void gvShowQuestionnaires_RowEdit(object sender, GridViewEditEventArgs e)
{
string id = gvShowQuestionnaires.Rows[e.NewEditIndex].Cells[0].Text;
Session["qID"] = id;
Response.Redirect("~/members/edit_questionnaire.aspx");
}
protected void showResponses(object sender, EventArgs e)
{
Button btn = (Button)sender;
string id = btn.CommandArgument.ToString();
Session["qID"] = id;
Response.Redirect("~/members/questionnaire_responses.aspx");
}
Any help would much appreciated.

It seems reasonably clear to me. Here:
<asp:GridView runat="server" ... OnRowCommand="showResponses">
you bind the RowCommand event to showResponses. And here, in showResponses, you assume that the sender is a button:
protected void showResponses(object sender, EventArgs e)
{
Button btn = (Button)sender;
string id = btn.CommandArgument.ToString();
Session["qID"] = id;
Response.Redirect("~/members/questionnaire_responses.aspx");
}
The sender isn't a button - it's the grid view. If you want the command argument, you should use GridViewCommandEventArgs.CommandArgument.
protected void showResponses(object sender, GridViewCommandEventArgs e)
{
Session["qID"] = e.CommandArgument;
Response.Redirect("~/members/questionnaire_responses.aspx");
}

Add a CommandName attribute to your button1 in the GridView.
<asp:Button runat="server" ID="button1" CommandName="Button1" CommandArgument='<%# Eval("QuestionnaireID") %>' OnClick="showResponses" text="Results"/>
Then in showResponses do this...
protected void showResponses(object sender, GridViewCommandEventArgs e)
{
if (e.CommandName == "Button1") {
Session["qID"] = e.CommandArgument;
Response.Redirect("~/members/questionnaire_responses.aspx");
}
}

var btnSender = (Button)e.CommandSource;

Problem with a hyperlink

I put a hyperlink inside a datalist..
<ItemTemplate>
<asp:HyperLink ID="HyperLink1" runat="server">'<%# Eval("ThreadTitle") %>'</asp:HyperLink>
<br />
<br />
</ItemTemplate>
I want it to enable it to be pressed so that the datalist event will be triggered and transfer me to another page:
protected void DataList1_SelectedIndexChanged(object sender, EventArgs e)
{
Server.Transfer("AnswerQuestion.aspx?x=" + DataList1.DataKeyField + "&question=" + DataList1.SelectedValue + "&time=" + DateTime.Now);
}
Unfortunately, the link seems to be disabled and I cant press on it to trigger the DataList Selected event..
How can I make the hyperlink active ?

If you want to trigger a selecteditemchaned event use a LinkButton instead of hyperlink.
<asp:DataList ID="DataList1" runat="server"
onselectedindexchanged="DataList1_SelectedIndexChanged">
<ItemTemplate>
<asp:LinkButton ID="sjdj" runat="server" CommandName="Select">
<%# Container.DataItem %></asp:LinkButton>
</ItemTemplate>
</asp:DataList>
In the code behind have
protected void DataList1_SelectedIndexChanged(object sender, EventArgs e)
{
Server.Transfer("~/jjtestjj.aspx?" + DataList1.DataKeyField);
}

why arent you using the Hyperlink as a hyperlink?
You can set the NavigationURL and Text using the OnItemDataBound (or equivalent) event.
this code works with an asp:Repeater:
protected void Row_DataItem(object row, RepeaterItemEventArgs args)
{
if (args.Item.ItemType == ListItemType.AlternatingItem || args.Item.ItemType == ListItemType.Item)
{
var item = (DataItemPOCO)args.Item.DataItem;
var link = (HyperLink)args.Item.FindControl("HyperLink1");
link.Text = item.LinkText;
link.NavigateUrl = item.URL;
}
}