bigO bigO - 1 month ago 12
ASP.NET (C#) Question

How to refresh Gridview after pressed a button in asp.net

I am trying to make a simple library database. I list the search results in a gridview, then i have a textbox and a button, user enters the isbn and clicks loan button. Then, if there is enough number of items (itemNumber>0) it is loaned by user. Here is the screenshot of user interface:

enter image description here

My question is, when user clicks loan button the loan may or may not be succesful. In both cases, i print a message indicating whether loan is succesful or not, and i also want the updated gridview to be displayed. The problem is, after pressing the loan button the gridview disappears and i just see the textbox, button and the message on the screen. How can i show the updated version of gridview after pressing loan button?

Here is the code file:

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="SearchResults.aspx.cs" Inherits="Pages_SearchResults" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>

</div>
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
DataKeyNames="ISBN" DataSourceID="SqlDataSource1"
onselectedindexchanged="GridView1_SelectedIndexChanged"
onrowcommand="GridView1_RowCommand">
<Columns>
<asp:BoundField DataField="Title" HeaderText="Title" SortExpression="Title" />
<asp:BoundField DataField="ISBN" HeaderText="ISBN" ReadOnly="True"
SortExpression="ISBN" />
<asp:BoundField DataField="AuthorName" HeaderText="AuthorName"
SortExpression="AuthorName" />
<asp:BoundField DataField="AuthorlName" HeaderText="AuthorlName"
SortExpression="AuthorlName" />
<asp:BoundField DataField="ItemType" HeaderText="ItemType"
SortExpression="ItemType" />
<asp:BoundField DataField="PublishYear" HeaderText="PublishYear"
SortExpression="PublishYear" />



<asp:BoundField DataField="numOfCopies" HeaderText="Number of Copies"
SortExpression="numOfCopies" />



</Columns>
</asp:GridView>
<asp:SqlDataSource ID="SqlDataSource1" runat="server"
ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
SelectCommand="SELECT * FROM [Items] WHERE ([Title] LIKE '%' + @Title + '%')">
<SelectParameters>
<asp:FormParameter FormField="tSearchBox" Name="Title" Type="String" />
</SelectParameters>
</asp:SqlDataSource>
<br />
<asp:Label ID="Label1" runat="server" Text="Type ISBN to loan:"></asp:Label>


  

   










And here is the .cs file:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;

public partial class Pages_SearchResults : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

}
protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
{
Response.Redirect("Default.aspx");
}


protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
{
SqlConnection con = new SqlConnection();
con.ConnectionString = "Data Source=.\\SQLEXPRESS;AttachDbFilename=D:\\Users\\SUUSER\\Documents\\Visual Studio 2010\\Projects\\Library\\LibWebSite\\App_Data\\LibDatabase.mdf;Integrated Security=True;User Instance=True";

Int32 verify;

string title = GridView1.HeaderRow.Cells[0].Text, isbn = GridView1.HeaderRow.Cells[1].Text, name = GridView1.HeaderRow.Cells[2].Text, lname = GridView1.HeaderRow.Cells[3].Text, type = GridView1.HeaderRow.Cells[4].Text, year = GridView1.HeaderRow.Cells[5].Text;


}
protected void bLoanButton_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection();
con.ConnectionString = "Data Source=.\\SQLEXPRESS;AttachDbFilename=D:\\Users\\SUUSER\\Documents\\Visual Studio 2010\\Projects\\Library\\LibWebSite\\App_Data\\LibDatabase.mdf;Integrated Security=True;User Instance=True";

string user = "select CurrentID from CurrentUser";

SqlCommand cmd1 = new SqlCommand(user, con);
con.Open();
string get = cmd1.ExecuteScalar().ToString();

string query1 = "insert into LoanTable(StudId,ISBN,onBorrow) values ("
+ "'" + get + "'" + "," + "'" + tLoanBox.Text + "'" + ","
+ "'" + "1" + "'" + ")";

string numQuery = "select numOfCopies from Items where ISBN='" + tLoanBox.Text + "'";

SqlCommand cmdnumQuery = new SqlCommand(numQuery, con);

SqlCommand cmd2 = new SqlCommand(query1, con);

int result;

int num=Convert.ToInt32(cmdnumQuery.ExecuteScalar());


result = cmd2.ExecuteNonQuery();

if (num > 0)
{

if (result > 0)
Response.Redirect("LoanSuccesfull.aspx");
}
else
notAvailable.Visible = true;

con.Close();


}
}


And here is the code for loan button:

protected void bLoanButton_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection();
con.ConnectionString = "Data Source=.\\SQLEXPRESS;AttachDbFilename=D:\\Users\\SUUSER\\Documents\\Visual Studio 2010\\Projects\\Library\\LibWebSite\\App_Data\\LibDatabase.mdf;Integrated Security=True;User Instance=True";

string user = "select CurrentID from CurrentUser";

SqlCommand cmd1 = new SqlCommand(user, con);
con.Open();
string get = cmd1.ExecuteScalar().ToString();

string query1 = "insert into LoanTable(StudId,ISBN,onBorrow) values ("
+ "'" + get + "'" + "," + "'" + tLoanBox.Text + "'" + ","
+ "'" + "1" + "'" + ")";





SqlCommand cmd2 = new SqlCommand(query1, con);

int result;




result = cmd2.ExecuteNonQuery();



if (result > 0)
{
loanSuccesful.Visible = true;
Response.Redirect("LoanSuccesfull.aspx");

}





con.Close();


}


I appreciate any help. Thanks

Answer

All you have to do is In your bLoanButton_Click , add a line to rebind the Grid to the SqlDataSource :

protected void bLoanButton_Click(object sender, EventArgs e)
{

//your same code
........

GridView1.DataBind();


}

regards