We Keep Coding

Data won't bind to a gridview based on a dropdown list selection

I currently have two dropdown lists and they are populated with names from a database. What I want to do is have a player be selected, and then on a button click, the data from the table is populated into a gridview. Right now I am just getting a "No data returned" message and I cannot figure out why.
<asp:DropDownList ID="ddl_QB1" runat="server" Width="200px" AppendDataBoundItems="True"
AutoPostBack="True" Height="16px" DataTextField="Player" DataValueField="id" ></asp:DropDownList>
<asp:Gridview ID="GridView1" runat="server" AutoGenerateColumns="false" Visible="true"
BackColor="White" BorderColor="#336666" BorderStyle="Double" BorderWidth="3px"
CellPadding="4" GridLines="Horizontal" ShowHeaderWhenEmpty="True" EmptyDataText="No records Found">
<Columns>
<asp:TemplateField HeaderText="Total Points">
<EditItemTemplate>
<asp:TextBox ID="TextBox2" runat="server" Text='<%# Bind("[Pts]") %>'>
</asp:TextBox>
</EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label2" runat="server" Text='<%# Bind("Pts") %>'>
</asp:Label>
</ItemTemplate>
protected void Page_Load(object sender, EventArgs e)
{
LoadQuarterbacks();
if (!Page.IsPostBack)
{
SqlConnection con = new SqlConnection(connectionstring);
SqlCommand cmd = new SqlCommand("select [id], [Player], [Pts], [Att], [Cmp], [Yds], [TD] from Quarterbacks", con);
SqlDataAdapter sda = new SqlDataAdapter(cmd);
DataTable dt = new DataTable();
sda.Fill(dt);
ddl_QB1.DataSource = dt;
ddl_QB1.DataBind();
}
}
private void LoadQuarterbacks()
{
ddl_QB1.Items.Clear();
ddl_QB2.Items.Clear();
SqlConnection con = new SqlConnection(connectionstring);
SqlCommand cmd = new SqlCommand("SELECT id, Player FROM Quarterbacks", con);
con.Open();
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataSet ds = new DataSet("Quarterbacks");
da.Fill(ds); // fill dataset
ddl_QB1.DataTextField = ds.Tables[0].Columns["Player"].ToString(); // text field name of table dispalyed in dropdown
ddl_QB2.DataTextField = ds.Tables[0].Columns["Player"].ToString();
ddl_QB1.DataValueField = ds.Tables[0].Columns["id"].ToString();
ddl_QB2.DataValueField = ds.Tables[0].Columns["id"].ToString(); // to retrive specific textfield name
ddl_QB1.DataSource = ds.Tables[0];
ddl_QB2.DataSource = ds.Tables[0];
ddl_QB2.DataBind();//assigning datasource to the dropdownlist
ddl_QB1.DataBind(); //binding dropdownlist
con.Close();
ddl_QB1.Items.Insert(0, new ListItem("--Select QuarterBack--", "0"));
ddl_QB2.Items.Insert(0, new ListItem("--Select QuarterBack--", "0"));
}
protected void Button1_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection(connectionstring);
string query = "SELECT [id], [Player], [Pts], [Att], [Cmp], [Yds], [TD] FROM Quarterbacks where id=" + ddl_QB1.SelectedValue;
SqlDataAdapter sda = new SqlDataAdapter(query,con);
con.Open();
DataTable dt = new DataTable();
sda.Fill(dt);
GridView1.DataSource = dt;
GridView1.DataBind();
}
}
}

Following 3 changes would give desired results.
First - AutoPostBack should be set to false on the dropdown element as that is causing postback even before you click on the button.
Second - remove the current code inside if(!Page.IsPostback). This code is not necessary. Also, this code is not setting DataTextField and DataValueField properties for ddl_QB1 and ddl_QB2.
Third - put the method call LoadQuarterbacks() inside if(!Page.IsPostback). We do not have to bind these values for ddl_QB1 and ddl_QB2 on each request.
If a refresh is required on the dropdown controls, then call LoadQuarterbacks() method after binding the gridview at the end of the button click. That way you are capturing the selected values from dropdown before rebinding the them. Rebinding the DropDowns would cause them loose the selected values.

Drop-down Selected Value not Showing in my Detailview

I have drop-down that is not showing the previoiusly selected value in my Detailview. It always shows me the first value in the list. If the previously selected value was xyz then when the Detailvies loads, i want to show xyz. I have researched a lot but could not find any solution that i can use. please help
here is my aspx code for the field that has the dropdown
<asp:TemplateField HeaderText="Name:">
<ItemTemplate>
<asp:Label ID="lbl_UID" runat="server" Text='<%# DataBinder.Eval(Container, "DataItem.Name") %>'></asp:Label></ItemTemplate>
<EditItemTemplate>
<asp:DropDownList ID="ddl_Name" Width="200px" Height="25" DataSourceID="SDS_Manager" DataTextField="FULL_NM" AutoPostBack="false"
DataValueField="UID" runat="server" AppendDataBoundItems="false">
<asp:ListItem Text="Select Name" Value="Select Name"></asp:ListItem>
</asp:DropDownList>
</EditItemTemplate>
</asp:TemplateField>
here is the code behind that binds the detailview
protected void Edit(object sender, EventArgs e)
{
using (GridViewRow row = (GridViewRow)((LinkButton)sender).Parent.Parent)
{
sqlcon.Open();
sqlcmd = new SqlCommand(#"Select PRJ_ID, WPC_CD, WPC_DESC, Name FROM myTable where PRJ_ID = '" + myvar + "' ", sqlcon);
da = new SqlDataAdapter(sqlcmd);
da.Fill(dt);
sqlcon.Close();
DV_Edit.DataSource = dt;
DV_Edit.DataBind();
sqlcon.Close();
popup.Show();
}
}

Try setting AutoPostBack="true" and make sure if you have any logic to set the value of the drop down in the page load, that the code is not executed on post back as shown below.
protected void Page_Load(object sender, EventArgs e) {
if (!IsPostBack) {
ddlOne.DataSource = //your data here;
ddlOne.DataBind();
}
}
//if you don't wrap this logic in the if(!IsPostBack), the code will simply re-populate
//the drop down and set the selected index to the first item in the list with each
//post back.

ASP.NET c# Checkboxlist in a template field

I a newbie to asp.net. I have created a DB table in sqlserver with 3 columns; ImageID, Filename & Score.
FileName is C:\pics\beads.png or C:\pics\moreimages\scenary.jpeg.
Using C# asp.net, I have created a GridView. This Gridview should populate
(column 1)ImageID and get the image from the Filename (column2) and I have 2 Checkboxlist created as shown below which should accept score for the images from user and save it into the DB table.
Question 1 .
I am able to populate Image ID, but Images are not getting populated.
Question 2.
I do not know how to access the checkboxlist since it is in template. The checked is in the default select and doesn't change even if I click on it. Which method/property should be used to do save the selection to the database. Here's my code
<form id="form1" runat="server">
<p style="height: 391px">
<asp:GridView ID="GridView1" runat="server" Caption="Logos" Height="299px" Width="577px" AutoGenerateColumns="False">
<Columns>
<asp:BoundField DataField="ImageID" HeaderText="ImageID" />
<asp:ImageField DataImageUrlField="FileName" ControlStyle-Width="100"
ControlStyle-Height="100" HeaderText="Image" AlternateText="No image">
<ControlStyle Height="100px" Width="100px"></ControlStyle>
</asp:ImageField>
<asp:TemplateField HeaderText="Score" AccessibleHeaderText="CheckBoxList" ValidateRequestMode="Enabled">
<ItemTemplate>
<asp:CheckBoxList runat="server" AutoPostBack="true" RepeatColumns="3" ID="test">
<asp:ListItem Selected="True" Value="5">Good</asp:ListItem>
<asp:ListItem Value="0">Not Good </asp:ListItem>
<asp:ListItem Value="3">OK</asp:ListItem>
</asp:CheckBoxList>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Save" Width="130px" />
<asp:Button ID="Button2" runat="server" OnClientClick="javaScript:window.close(); return false;" Text="Exit" Width="102px" />
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
</p>
</form>
public string sqlSel = #"SELECT TOP 3 [ImageID],FileName FROM [db1].[ImagesTest] where [Score] is null";
protected void Page_Load(object sender, EventArgs e)
{
using (SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["SQLConnectionString"].ConnectionString))
{
connection.Open();
SqlCommand cmdSel = new SqlCommand(sqlSel, connection);
SqlDataReader reader1 = cmdSel.ExecuteReader();
while (reader1.Read())
{
DataSet ds = GetData(sqlSel);
if (ds.Tables.Count > 0)
{
GridView1.DataSource = ds;
GridView1.DataBind();
}
else
{
Response.Write("Unable to connect to the database.");
}
}
}
}
private DataSet GetData(string cmdSel)
{
String strConnString = System.Configuration.ConfigurationManager.ConnectionStrings["SQLConnectionString"].ConnectionString;
DataSet ds = new DataSet();
try
{
SqlConnection con = new SqlConnection(strConnString);
SqlDataAdapter sda = new SqlDataAdapter(cmdSel,con);
sda.Fill(ds);
}
catch (Exception ex)
{
Response.Write("IN EXCEPTION "+ex.Message);
return null;
}
return ds;
}
Thanks for ur time
Rashmi

There are several issues with your code, here is what it should be fixed:
How to fix the images (Question 1)
As #Guilherme said in the comments, for images use URLs instead of disk paths.
Replace the images disk paths C:\pics\beads.png or C:\pics\moreimages\scenary.jpeg to something like Images/beads.png and Images/scenary.jpeg.
For this to work, you will need to have a folder named Images that contains these two files on the same directory level as your .aspx file.
Adjust your GridView1 declaration in the ASPX file
On your GridView1 declaration you should:
attach a handler to the OnRowDataBound event. This will allow you to properly bind the Score dataset column to the Score gridview column
set the DataKeyNames property on the grid to what should be the primary key for your images table (in this case DataKeyNames="ImageID")
use a RadioButtonList instead of a CheckboxList, because according to your dataset you can only set one value, which is what the RadioButtonList does. The CheckboxList is normally used when multiple selection is needed.
attach a handler to the SelectedIndexChanged event on the RadioButtonList. This will allow you to save the new values to the database (Question 2)
Here's how your GridView declaration should look like:
<asp:GridView ID="GridView1" runat="server" Caption="Logos" Height="299px" Width="577px" AutoGenerateColumns="False" OnRowDataBound="GridView1_RowDataBound" DataKeyNames="ImageID">
<Columns>
<asp:BoundField DataField="ImageID" HeaderText="ImageID" />
<asp:ImageField DataImageUrlField="FileName" ControlStyle-Width="100"
ControlStyle-Height="100" HeaderText="Image" AlternateText="No image">
<ControlStyle Height="100px" Width="100px"></ControlStyle>
</asp:ImageField>
<asp:TemplateField HeaderText="Score" AccessibleHeaderText="RadioButtonList" ValidateRequestMode="Enabled">
<ItemTemplate>
<asp:RadioButtonList runat="server" AutoPostBack="true" RepeatColumns="3" ID="test" OnSelectedIndexChanged="test_SelectedIndexChanged">
<asp:ListItem Value="5">Good</asp:ListItem>
<asp:ListItem Value="0">Not Good </asp:ListItem>
<asp:ListItem Value="3">OK</asp:ListItem>
</asp:RadioButtonList>
<!-- UPDATED! - keep the old values in a hidden field -->
<asp:HiddenField runat="server" ID="hfOldScore" Value='<%# Eval("Score") %>' />
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
Adjust your code behind value in your .ASPX.CS file (Question 2)
On the code behind, you will also need to:
Make sure you are binding to the GridView only once in the Page_Load event, by checking the IsPostBack property
(Optional, but recommended) Move the logic of getting data (with the SQLConnection code) in a separate method that will handle only data retrieval
Implement the handler for the OnRowDataBound event. This will bind any values from the Score column to the RadioButtonList control
Implement the handler for the SelectedIndexChecked event of the RadioButtonList control. This will allow you to save to the database the new values
Finally, here's the entire code-behind code:
protected void Page_Load(object sender, EventArgs e)
{
//bind only the first time the page loads
if (!IsPostBack)
{
DataSet ds = GetData(sqlSel);
if (ds.Tables.Count > 0)
{
GridView1.DataSource = ds;
GridView1.DataBind();
}
else
{
Response.Write("Unable to connect to the database.");
}
}
}
private DataSet GetData(string cmdSel)
{
//normally you should query the data from the DB
//I've manually constructed a DataSet for simplification purposes
DataSet ds = new DataSet();
DataTable dt = new DataTable();
dt.Columns.Add(new DataColumn("ImageID", typeof(int)));
dt.Columns.Add(new DataColumn("FileName", typeof(string)));
dt.Columns.Add(new DataColumn("Score", typeof(int)));
dt.Rows.Add(100, #"Images/beads.png", 0);
dt.Rows.Add(200, #"Images/moreimages/scenary.jpeg", 3);
dt.Rows.Add(300, #"Images/moreimages/scenary.jpeg", 5);
ds.Tables.Add(dt);
return ds;
}
protected void Button1_Click(object sender, EventArgs e)
{
//UPDATED - iterate through all the data rows and build a dictionary of items
//to be saved
Dictionary<int, int> dataToUpdate = new Dictionary<int, int>();
foreach (GridViewRow row in GridView1.Rows)
{
if (row.RowType == DataControlRowType.DataRow)
{
int imageID = (int)GridView1.DataKeys[row.RowIndex].Value;
int oldScore;
int newScore;
int.TryParse((row.FindControl("hfOldScore") as HiddenField).Value, out oldScore);
int.TryParse((row.FindControl("test") as RadioButtonList).SelectedValue, out newScore);
if (oldScore != newScore)
{
dataToUpdate.Add(imageID, newScore);
}
}
}
//update only the images that were changed
foreach (var keyValuePair in dataToUpdate)
{
SaveToDB(keyValuePair.Key, keyValuePair.Value);
}
}
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
//we are only interested in the data Rows
if (e.Row.RowType == DataControlRowType.DataRow)
{
DataRow dataRow = (e.Row.DataItem as DataRowView).Row;
//manually bind the Score column to the RadioButtonlist
int? scoreId = dataRow["Score"] == DBNull.Value ? (int?)null : (int)dataRow["Score"];
if (scoreId.HasValue)
{
RadioButtonList test = e.Row.FindControl("test") as RadioButtonList;
test.ClearSelection();
test.SelectedValue = scoreId.Value.ToString();
}
}
}
protected void test_SelectedIndexChanged(object sender, EventArgs e)
{
RadioButtonList test = sender as RadioButtonList;
GridViewRow gridRow = test.NamingContainer as GridViewRow;
//obtain the current image Id
int imageId = (int)GridView1.DataKeys[gridRow.RowIndex].Value;
//obtain the current selection (we will take the first selected checkbox
int selectedValue = int.Parse(test.SelectedValue);
//UPDATED! - saves are now handled on the Save button click
//SaveToDB(imageId, selectedValue);
}
private void SaveToDB(int imageId, int score)
{
//UPDATED!
using (SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["SQLConnectionString"].ConnectionString))
{
connection.Open();
using (SqlCommand command = connection.CreateCommand())
{
command.Parameters.Add("#ImageID", imageId);
command.Parameters.Add("#Score", score);
command.CommandText = #"update [db1].[ImagesTest] set Score = #Score where [ImageID] = #ImageID";
command.ExecuteNonQuery();
}
}
}
UPDATED!
The declaration of the GridView1 now contains a hidden field containing the Score value. You can use this hidden field to determine which row has changed, so you can trigger a save only on the changed ones
Save is now done on the click of the Save button, by iterating through the rows of the grid an building a Dictionary<int,string> to keep only the changes.
SaveToDB method should work, but I cannot test this myself.

Question 2:
To access your checkbox you can use.
GridViewRow row = GridView1.Rows[i];
CheckBox Ckbox = (CheckBox)row.FindControl("test");

For Question 1
Instead of ImageField you can use use ASP:Image in Templatefield like this
<asp:TemplateField HeaderText="Score" AccessibleHeaderText="CheckBoxList" ValidateRequestMode="Enabled">
<ItemTemplate>
<asp:Image ID="imageControl" runat="server" ImageUrl='<%# Eval("Filename") %>'></asp:Image>
</ItemTemplate>
</asp:TemplateField>
For Question 2
This is one of the example for how to access each Checkbox list inside gridview
For Each gvr As GridViewRow In Gridview1.Rows
If (CType(gvr.FindControl("CheckBox1"), CheckBox)).Checked = True Then
ReDim uPrimaryid(iCount)
uPrimaryid(iCount) = New Integer
uPrimaryid(iCount) = gvr.Cells("uPrimaryID").Text
iCount += 1
End If
Next

how to get values in dropdownlist bounded within a gridview?

Inside gridview a dropdownlist is there
<asp:TemplateField HeaderText="Quantity">
<ItemTemplate>
<asp:DropDownList ID="quantity" runat="server" DataValueField="ItemID" DataTextField="Quantity">
</asp:DropDownList>
</ItemTemplate>
</asp:TemplateField>
for each itemid there is some numeric value in Quantity field of Database Table
i want that this dropdown must contain the values from 1 to quantity.DataTextField for all the items present in the cart
the procedure by which gridview is bound is
create proc [dbo].[prcItemsinCart](#CartID int)
as
select distinct ct.Price,ct.Quantity,ct.ItemID,
ct.CartID,ct.ProductID,p.ProductName,
isnull(( select top 1 convert(varchar,PhotoID,10) + '.' + ExtName
from ProductPhoto
where ProductID = ct.ProductID ),'NoImage.jpg'
) as Product,
( Select Price*Quantity
from CartItems
where CartID=ct.CartID and ProductID=ct.ProductID
) as SubTotal
from CartItems as ct
inner join ProductInfo as p on ct.ProductID=p.ProductID
inner join ProductPhoto as pp on ct.ProductID=pp.ProductID
where ct.CartID=#CartID

I would add a HiddenField in the TemplateField to hold the CartID, I will use the CartID in the code. My Markup should look like:
<asp:TemplateField HeaderText="Quantity">
<ItemTemplate>
<asp:HiddenField ID="hdnId" runat="server" value='<%#Eval("CartID") %>'></asp:HiddenField>
<asp:DropDownList ID="quantity" runat="server" DataValueField="ItemID" DataTextField="Quantity">
</asp:DropDownList>
</ItemTemplate>
</asp:TemplateField>
In the code, in GridView's RowDataBound I am finding the DropDownList and HiddenField, running a Sql Query to bring my expected data, and binding them to my DropdownList:
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
DropDownList quantity = e.Row.FindControl("quantity") as DropDownList;
HiddenField hdnId = e.Row.FindControl("hdnId") as HiddenField;
if (quantity != null && hdnId != null)
{
string queryString = String.Format("SELECT ItemID, Quantity FROM CartItems WHERE CartID= {0}", hdnId.Value);
//MyConnectionString is your connection string in web.config
using (SqlConnection connection = new SqlConnection(ConfigurationManager.ConnectionStrings["MyConnectionString"].ToString()))
{
SqlCommand command = new SqlCommand(queryString, connection);
connection.Open();
SqlDataReader reader = command.ExecuteReader();
quantity.DataSource = reader;
quantity.DataValueField = "ItemID";
quantity.DataTextField = "Quantity";
quantity.DataBind();
}
}
}
}

Grid view Dropdown list data binding error

Am using the below code to bind the dropdown data from another table. And also refer that control name using rowindex. But it always return null.And also return the error message.
`Object reference not set to an instance of an object.`
Am using the two method, but both return the control name null
First code:
protected void GridView2_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
Control ctrl = e.Row.FindControl("DDL_STATUS_FT"); //It always return null
if (ctrl != null)
{
DropDownList dd = ctrl as DropDownList;
DataSet7TableAdapters.sp_getall_trv_masterTableAdapter TA = new DataSet7TableAdapters.sp_getall_trv_masterTableAdapter();
DataSet7.sp_getall_trv_masterDataTable DS = TA.GetData();
dd.DataTextField = "fld_TName";
dd.DataValueField = "fld_id";
dd.DataSource = DS;
dd.DataBind();
}
}
}
Second :
In databind function
if (DS.Rows.Count > 0)
{
GridView2.DataSource = DS;
GridView2.DataBind();
foreach (GridViewRow grdRow in GridView2.Rows)
{
DataSet7TableAdapters.sp_getall_trv_masterTableAdapter TA1 = new DataSet7TableAdapters.sp_getall_trv_masterTableAdapter();
DataSet7.sp_getall_trv_masterDataTable DS1 = TA1.GetData();
// Nested DropDownList Control reference is passed to the DrdList object. This will allow you access the properties of dropdownlist placed inside the GridView Template column.
DropDownList drdList = (DropDownList)(GridView2.Rows[grdRow.RowIndex].Cells[4].FindControl("DDL_STATUS_FT"));//It always return null
// DataBinding of nested DropDownList Control for each row of GridView Control.
drdList.DataSource = DS1;
drdList.DataValueField = "fld_id";
drdList.DataTextField = "fld_TName";
drdList.DataBind();
}
}
Please help me to do this..
<asp:TemplateField ItemStyle-Width="100px" HeaderText="TYPE">
<ItemTemplate>
<asp:DropDownList ID="DDL_STATUS" runat="server" AutoPostBack="true" Enabled="false" >
</asp:DropDownList>
</ItemTemplate>
<EditItemTemplate>
<asp:DropDownList ID="DDL_edit_STATUS" runat="server" AutoPostBack="true" SelectedValue='<%# Eval("fld_Type") %>'>
</asp:DropDownList>
</EditItemTemplate>
<FooterTemplate>
<asp:DropDownList ID="DDL_STATUS_FT" runat="server" AutoPostBack="true">
</asp:DropDownList>
</FooterTemplate>
</asp:TemplateField>

The DropDown "DDL_STATUS_FT" is in Footer Template..You must check it as follow..
if(e.Row.RowType == DataControlRowType.Footer)
{
DropDownList ctrl =(DropDownList)e.Row.Cells[CellIndex].FindControl("DDL_STATUS_FT");
}

Try to find your control by cell and cellIndex like...
Control ctrl = e.Row.Cells[yourCellIndex].FindControl("DDL_STATUS_FT");

EDITED2
you must have dropdownlist in aspx code in gridview item-template
you are finding using e.row.findcontrol without declaring it so abusively it return null
so, fist add dropdownlist into your gridview
here is a sample of your dropdownlist
<asp:TemplateField ItemStyle-Width="30px" HeaderText="DDL_STATUS_FT">
<ItemTemplate>
<asp:Dropdownlist ID="DDL_STATUS_FT" runat="server" />
</ItemTemplate>
</asp:TemplateField>
if you got null ctrl
Control ctrl = e.Row.FindControl("DDL_STATUS_FT"); //It always return null
then make sure in your aspx code DDL_STATUS_FT Control is runat="server"