Develop Reference

First Click on ASP.NET control does not fire on click event

I'm seeing this behavior on two of my pages, but I'm just going to ask about the one that's more important to me at the moment. I have a page that loads information from a database into a ASP gridview and then allows the user to add a detail to each populated line.
The issue I'm having is that when the 'Edit' button of the gridview and then subsequently the 'Update' or 'Cancel' button, it takes two click to actually fire the onclick event. A post back does take place on the first click, but nothing actually happens.
I'm including the code that seems relevant below. The page uses a master page and there are a number of divs involved with formatting, I'm excluding those.
Gridview and related controls:
<asp:UpdatePanel runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:Label Text="Plant Selector: " runat="server" />
<asp:DropDownList ID="ddlPlant" OnSelectedIndexChanged="ddlPlant_SelectedIndexChanged" runat="server" />
<asp:Button ID="btnUpdate" Text="Update" OnClick="btnUpdate_Click" runat="server" />
<p />
<asp:Label ID="lblTest" Text="" runat="server" />
<asp:Label ID="lblerror" Text="" ForeColor="Red" runat="server" />
<asp:GridView ID="gridview1" AutoGenerateColumns="false" runat="server" OnRowEditing="gridview1_RowEditing" OnRowCancelingEdit="gridview1_RowCancelingEdit" OnRowUpdating="gridview1_RowUpdating">
<Columns>
<asp:BoundField DataField="JobNum" HeaderText="Job Number" ReadOnly="true" />
<asp:BoundField DataField="ModelNum" HeaderText="Model" ReadOnly="true" />
<asp:BoundField DataField="Customer" HeaderText="Customer" ReadOnly="true" />
<asp:BoundField DataField="SchCompDate" HeaderText="Sch Comp Date" ReadOnly="true" />
<asp:TemplateField HeaderText="Details">
<EditItemTemplate>
<asp:TextBox ID="Txt" Width="98%" runat="server" />
</EditItemTemplate>
<ItemTemplate>
<asp:Label Text="Click Edit to add details of exception." runat="server" />
</ItemTemplate>
</asp:TemplateField>
<asp:CommandField ShowEditButton="true" />
</Columns>
</asp:GridView>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="gridview1" />
</Triggers>
</asp:UpdatePanel>
Sample image below:
Here is the code behind:
private string Plant { get; set; }
// This sets the default plant based off IP.
protected void Page_PreInit(Object sender, EventArgs e)
{
getPlantFromIP();
}
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
populateDDL();
BindData();
}
else
{
Plant = ddlPlant.SelectedValue.ToString();
}
}
// Populates the drop down.
private void populateDDL()
{
ddlPlant.Items.Add("NC");
ddlPlant.Items.Add("WA");
setPlantInDDL();
}
private void setPlantInDDL()
{
if(Plant == "WA")
{
ddlPlant.SelectedIndex = 1;
}
if (Plant == "NC")
{
ddlPlant.SelectedIndex = 0;
}
}
private void getPlantFromIP()
{
if (Request.ServerVariables["REMOTE_ADDR"] == "70.103.118.100")
{
Plant = "WA";
//ddlPlant.SelectedIndex = 1;
}
else
{
Plant = "NC";
//ddlPlant.SelectedIndex = 0;
}
}
// Database Query.
private DataTable getDataFromDatabase()
{
DataTable rTable = new DataTable();
string plant = ddlPlant.SelectedValue.ToString();
using (var conn = new MySqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["workorderConnectionString"].ConnectionString))
{
conn.Open();
using (var cmd = conn.CreateCommand())
{
try
{
cmd.CommandText = #"SELECT * FROM reportdatatables.compliance_exception_report
WHERE ExceptionNoted = '0' AND Plant = #plant";
cmd.Parameters.AddWithValue("#plant", plant);
MySqlDataReader reader = cmd.ExecuteReader();
rTable.Load(reader);
reader.Close();
cmd.Dispose();
}
catch
{
}
finally
{
conn.Close();
}
}
}
return rTable;
}
// Binds the data from the database to the gridview.
private void BindData()
{
DataTable data = getDataFromDatabase().Copy();
gridview1.DataSource = data;
gridview1.DataBind();
}
protected void ddlPlant_SelectedIndexChanged(object sender, EventArgs e)
{
//Plant = ddlPlant.SelectedValue.ToString();
BindData();
}
// On edit call.
protected void gridview1_RowEditing(object sender, GridViewEditEventArgs e)
{
}
// On cancel call.
protected void gridview1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
{
gridview1.EditIndex = -1;
}
protected void gridview1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
}
protected void btnUpdate_Click(object sender, EventArgs e)
{
BindData();
}
Here's what I've tried:
-A lot of posts a read saw this behavior relating to autopostback settings of controls. As you can see I'm made sure to not have any control with the autopostback set to true.
-I had some concern that the behavior might be related to the updatepanel, but removing it doesn't change the behavior at all.
-I read that having AutoEventWireup="true" in your page tag can cause this. I DO have that in my page tag, but setting it to false does not fix the issue and prevents my dropdown from being populated on page load.
-There was another post that suggested the ID of the control could be changing between page load and post back. I monitored the IDs of those controls and I do not see any change in their ID.
So all that being said, I'm hoping someone has a clue as to what I'm missing. If there is any more information I can provide that might help, please let me know.
Thank you in advance.

Try this, which will make the grid editable
protected void gridview1_RowEditing(object sender, GridViewEditEventArgs e)
{
GridView1.EditIndex = e.NewEditIndex;
BindData();
}
for cancel also
protected void gridview1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
{
gridview1.EditIndex = -1;
BindData();
}

Variables lost on postback in asp.net

I have a gridview with some data and I want to add a checkbox column which can choose multiple rows. By clicking on it I want to save an primary key of row and change css class of row.
Using this article(step 2) I created itemtemplate,added there a checkbox(specifying ID as TransactionSelector), and add a checkedChange() to it. There I only change a css class of row and add a row index to arraylist. But when I click button with event which show this list, it has no items.
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" >
<Columns>
<asp:TemplateField>
<ItemTemplate>
<asp:CheckBox ID="TransactionSelector" runat="server"
oncheckedchanged="TransactionSelector_CheckedChanged" AutoPostBack="True" />
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField DataField="iTransactionsId" HeaderText="iTransactionsId"
SortExpression="iTransactionsId" />
<asp:BoundField DataField="mAmount" HeaderText="mAmount"
SortExpression="mAmount" />
<asp:BoundField DataField="vchTransactionType" HeaderText="vchTransactionType"
SortExpression="vchTransactionType" />
<asp:BoundField DataField="dtDate" HeaderText="dtDate"
SortExpression="dtDate" />
<asp:BoundField DataField="cStatus" HeaderText="cStatus"
SortExpression="cStatus" />
<asp:BoundField DataField="test123" HeaderText="test123"
SortExpression="test123" />
</Columns>
<RowStyle CssClass="unselectedRow" />
</asp:GridView>
</asp:Panel>
<asp:Panel ID="InfoPanel" runat="server" CssClass="infoPanel">
<asp:Button ID="ShowSelected" runat="server" Text="Button"
onclick="ShowSelected_Click" />
<asp:Label ID="InfoLabel" runat="server"></asp:Label>
</asp:Panel>
C Sharp code:
public partial class WebForm1 : System.Web.UI.Page
{
ArrayList indices = new ArrayList();
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
GridView1.DataSourceID = "SqlDataSource1";
GridView1.DataBind();
}
}
protected void TransactionSelector_CheckedChanged(object sender, EventArgs e)
{
CheckBox cb = (CheckBox)sender;
GridViewRow row = (GridViewRow)cb.NamingContainer;
// row.CssClass = (cb.Checked) ? "selectedRow" : "unselectedRow";
if (cb.Checked)
{
row.CssClass = "selectedRow";
indices.Add(row.RowIndex);
}
else
{
row.CssClass = "unselectedRow";
indices.Remove(row.RowIndex);
}
}
protected void ShowSelected_Click(object sender, EventArgs e)
{
InfoLabel.Text = "";
foreach (int i in indices)
{
InfoLabel.Text += i.ToString() + "<br>";
}
}
}
}

You have to persist variable in postback using ViewState. Also its better if you use List<T> generic implementation rather than ArrayList
ViewState["Indices"] = indices;
And to recover it back
indices = ViewState["Indices"] as ArrayList;

As Habib said, you could use ViewState. You could also use ControlState instead, as shown here. If your code is in a custom control or user control, you may also need to override OnInit to
protected override void OnInit(EventArgs e)
{
base.OnInit(e);
Page.RegisterRequiresControlState(this);
}
Please feel free to respond with feedback. I'm new at posting answers.

Selecting row of DataGridView?

How do i have the whole row of a data grid view. I have no idea where to start. I have tried this, but has NO idea where to PUT it. :
dataGrid.Rows[index].Selected = true;
I am just looking for a peice of code that will help me! Thanks

It seems you want to do something like this:
protected void Page_Load(object sender, EventArgs e)
{
this.FillGrid();
}
protected void GridView1_SelectedIndexChanging(object sender, GridViewSelectEventArgs e)
{
this.GridView1.SelectedIndex = e.NewSelectedIndex;
this.FillGrid();
}
private void FillGrid()
{
this.GridView1.DataSource = new[] { "Hello", "World" };
this.GridView1.DataBind();
}
And in the aspx file:
<asp:GridView ID="GridView1" runat="server"
onselectedindexchanging="GridView1_SelectedIndexChanging">
<Columns>
<asp:CommandField ShowSelectButton="True" />
</Columns>
<SelectedRowStyle BackColor="DarkSlateBlue" ForeColor="GhostWhite" />
</asp:GridView>
Which produces this output:

Gridview with Enable and Disable image buttons

I have gridview in an asp.net application. I want to insert a column with image buttons where by click on it will enable or disable users or change the status field in db and also change the image button image accordingly user status.
Meaning: I want to display different images for disabled and enabled users.
How can I do this in C# and bind the data to the image button?
Anyone please help. Thanks in advance.

Make use of the ItemDataBound event. This is where you can check each row of your grid and apply changes to it. Then you can hide / unhide or change buttons:
VB.net below but you can easily convert to C#:
Dim ib As ImageButton = CType(e.Item.FindControl("ibFav"), ImageButton)
ib.Visible = False
Dim ib2 As ImageButton = CType(e.Item.FindControl("ibRemFav"), ImageButton)
ib2.Visible = True

Sample User Model:
public class UserModel {
public string Name { get; set; }
public bool IsEnabled { get; set; }
}
Here is the GridView Code:
<asp:GridView ID="GridView" runat="server" AutoGenerateColumns="false"
onrowcommand="GridView_RowCommand" onrowdatabound="GridView_RowDataBound">
<Columns>
<asp:TemplateField>
<ItemStyle HorizontalAlign="Center" />
<ItemTemplate>
<asp:ImageButton ID="EnabledImgBtn" runat="server"
CommandArgument='<%# Eval("Name") %>'
CommandName="ResetUserState" />
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField DataField="Name" HeaderText="Name" />
//Other columns....
</Columns>
</asp:GridView>
Set the 'CommandArgument' according to your needs. e.g the ID of the User.
Sample Code-behind for the gridview:
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack){
LoadGridView();
}
}
private void LoadGridView()
{
this.GridView.DataSource = GetUsersFromDatabase();
this.GridView.DataBind();
}
protected void GridView_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
var user = e.Row.DataItem as UserModel;
var enabledImgBtn = e.Row.FindControl("EnabledImgBtn") as ImageButton;
if (enabledImgBtn != null)
enabledImgBtn.ImageUrl = user.IsEnabled ? "~/YourImagePath/enabled.png"
: "~/YourImagePath/disalbed.png";
}
}
protected void GridView_RowCommand(object sender, GridViewCommandEventArgs e)
{
if (e.CommandName == "ResetUserState")
{
if (e.CommandArgument!= null)
{
var userName = e.CommandArgument.ToString();
//Change user enabled state and Update database
//Sample code:
var user = FindUserByName("userName");
user.IsEnabled = !user.IsEnabled;
//SaveInDatabase(user);
LoadGridView();
}
}
}
You may consider using 'CommandField' with Type equal to 'Image' instead of 'TemplateField', but there is an issue with this approach, read more.
Hope this helps.

<asp:GridView ID="GridView" runat="server" AutoGenerateColumns="false"
onrowcommand="GridView_RowCommand" onrowdatabound="GridView_RowDataBound">
<Columns>
<asp:TemplateField HeaderText="Change Status" ItemStyle-CssClass="GrdItemImg">
<ItemTemplate>
<asp:ImageButton ID="ibtnChangeActiveStatus" CommandArgument='<%#Eval("RecordID")%>'
CommandName='GRDSTATUS' runat="server" ImageUrl='<%# getStatusImage(Convert.ToInt32(DataBinder.Eval(Container.DataItem,"IsApproved"))) %>' />
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField DataField="Col2" HeaderText="Col2" />
//Other Respective columns....
...........
..........
</Columns>
</asp:GridView>
And In CS file add the following function.
public string getStatusImage(int intStatus)
{
string strStatus = string.Empty;
if (intStatus == 1)
{
strStatus = "~/images/active.png";
}
else
{
strStatus = "~/images/inactive.png";
}
return strStatus;
}
So on the base of "intStatus" respective active / InActive Image will be set.

ASP .NET - Setting the value of a DetailsView TextBox

I am attempting to use the code-behind (Page_Load or PreRender) to set a date-time textbox in a DetailsView so that it defaults to a current date-time.
What I have attempted is (one of many variations):
protected void DetailsView2_PreRender(object sender, EventArgs e)
{
((TextBox)DetailsView2.FindControl("date_time")).Text =
DateTime.Now.ToString("d");
}
But all that I get is a 'NullReferenceException' error.
What I am doing wrong?

You can use detailsview controls DataBound event to set a value within your detailsview like that :
<asp:Label ID="DetailsView2" runat="server" OnDataBound="DetailsView2_DataBound">
</asp:Label>
Code Behind :
protected void DetailsView2_DataBound(object sender, EventArgs e)
{
DetailsView myDetailsView = (DetailsView)sender;
if(myDetailsView.CurrentMode == DetailsViewMode.Edit)
{
((TextBox)myDetailsView.FindControl("date_time")).Text = DateTime.Now.ToString("d");
}
}

To add to what Canavar suggested:
For use on a DetailsView assign like this:
<asp:DetailsView ID="DetailsView2" runat="server" AutoGenerateRows="False"
CellPadding="4" DataKeyNames="details_id" DataSourceID="SqlDataSource4"
DefaultMode="Insert" ForeColor="#333333" GridLines="None" Height="50px"
Width="125px"
AllowPaging="True" OnPreRender="DetailsView2_DataBound">
And then in the code behind:
protected void DetailsView2_DataBound(object sender, EventArgs e)
{
DetailsView myDetailsView = (DetailsView)sender;
//Edit
if (myDetailsView.CurrentMode == DetailsViewMode.Edit)
{
((TextBox)myDetailsView.FindControl("TextBox2")).Text = DateTime.Now.ToString("g");
}
//Insert
else if (myDetailsView.CurrentMode == DetailsViewMode.Insert)
{
((TextBox)myDetailsView.FindControl("TextBox2")).Text = DateTime.Now.ToString("M/d/yyyy HH:mm");
}
}