search againest database

Question

i'm facing the error while i'm developing search againest database with the help of autocompletion ,when user enters the name and clicks the go button i'm trying to pull the data bbut i have this error...none of my google results solve my problem .can any one solve this

Null reference exception was handled by user code
" Object reference not set to an instance of an object."

public partial class search1 : System.Web.UI.Page
    {
        SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings["conn"].ConnectionString);
        protected void Page_Load(object sender, EventArgs e)
        {
            SqlDataAdapter da = new SqlDataAdapter("select * from Candidate1 where name = '"+Session["name"].ToString()+"'", cn);
            DataSet ds = new DataSet();
            da.Fill(ds);
            DataList1.DataSource = ds.Tables[0];
            DataList1.DataBind();
        }
    }

Thanks and Regards

Muralidharan Deenathayalan · Answer

Hi Just wanted to know exactly where're you assigning the username into the session. In your code i couldn't see that lin. I'm expecting something like Session[name] = ; Before passing the name into the sqlit is safer to a null check. protected void Page_Load(object sender EventArgs e) { string name = Convert.ToString( Session[name]); if ( name ==  or string.IsNullOrEmpty ( name)) throw new Exception(Name not found); SqlDataAdapter da = new SqlDataAdapter(select * from Candidate1 where name = '+name+' cn); DataSet ds = new DataSet(); da.Fill(ds); DataList1.DataSource = ds.Tables[0]; DataList1.DataBind(); } Hope this helps you !

Iftikar Hussain · Answer

you need to keep the mouse on temp and then check the value if you can share your screen then use this https://join.me/ Regards Iftikar

aditya immadi · Answer

the onnnection string fine ..but i dont know how to see session value in debugging sorry for the inconviniance...i'm ssendig the picture please check the attachment

Iftikar Hussain · Answer

I got it the issue is may be the session value is not assigned properly or the connection string is not defined in web.config. Therefor I am asking to debug your code by putting the break point and check the session value weather it is coming or not? Regards Iftikar

aditya immadi · Answer

Dear Iftikari'm totally confusing...im sending the code for u this is mmy generic handler i.e; search.ashx using System; using System.Data.SqlClient; using System.Text; using System.Web; public class Search : IHttpHandler { public void ProcessRequest (HttpContext context) { string searchText = context.Request.QueryString[q]; SqlConnection con = new SqlConnection(Data Source=FOODASURA-PC\MYSQLAPCAMP;Initial Catalog=Apcampaign;Persist Security Info=True;User ID=sa;Password=123); con.Open(); SqlCommand cmd = new SqlCommand(select idnameimage from Candidate1 where name Like @Search + '%' con); cmd.Parameters.AddWithValue(@SearchsearchText); StringBuilder sb = new StringBuilder(); using(SqlDataReader dr=cmd.ExecuteReader()) { while(dr.Read()) { sb.Append(string.Format({0}{1}{2} dr[name] dr[image] Environment.NewLine)); } } con.Close(); context.Response.Write(sb.ToString()); } public bool IsReusable { get { return false; } } } and my search.aspx is ' /> ' /> '> '> '> '> '> and my search.aspx.cs is using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Data; using System.Data.SqlClient; using System.Configuration; namespace ApComapaign { public partial class search1 : System.Web.UI.Page { SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings[conn].ConnectionString); protected void Page_Load(object sender EventArgs e) { object temp = Session[name]; SqlDataAdapter da = new SqlDataAdapter(select * from Candidate1 where name = '+Session[name].ToString()+' cn); DataSet ds = new DataSet(); da.Fill(ds); DataList1.DataSource = ds.Tables[0]; DataList1.DataBind(); } } } thanksand and Regards

Iftikar Hussain · Answer

what value you are getting if put the break point for the below line object temp= Session[name]; Regards Iftikar

aditya immadi · Answer

the same error is continuing

Iftikar Hussain · Answer

can you the break point in below higlighted text and check the value public partial class search1 : System.Web.UI.Page { SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings[conn].ConnectionString); protected void Page_Load(object sender EventArgs e) { object temp= Session[name]; SqlDataAdapter da = new SqlDataAdapter(select * from Candidate1 where name = '+Session[name].ToString()+' cn); at this line Object reference not set to an instance of an object. DataSet ds = new DataSet(); da.Fill(ds); DataList1.DataSource = ds.Tables[0]; DataList1.DataBind(); } } Regards Iftikar

aditya immadi · Answer

i m using that text box for search againest databaseand i need to maintain that searchbox all the oages thats why i used it in master page

aditya immadi · Answer

but still i'm getting error in my search.aspx.cs the error is Object reference not set to an instance of an object. i think everythig is fie { public partial class search1 : System.Web.UI.Page { SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings[conn].ConnectionString); protected void Page_Load(object sender EventArgs e) { SqlDataAdapter da = new SqlDataAdapter(select * from Candidate1 where name = '+Session[name].ToString()+' cn); at this line Object reference not set to an instance of an object. DataSet ds = new DataSet(); da.Fill(ds); DataList1.DataSource = ds.Tables[0]; DataList1.DataBind(); } } } Thanks and Regards

Iftikar Hussain · Answer

modify your master page like this namespace ApComapaign { public partial class master : System.Web.UI.MasterPage { SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings[conn].ConnectionString); protected void Page_Load(object sender EventArgs e) { } protected void btn_search_Click(object sender EventArgs e) { Session[name]= txtSearch.Text; Response.Redirect(search.aspx); } protected void Button1_Click(object sender EventArgs e) { } } } Regards Iftikar

aditya immadi · Answer

This is my masterpage using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using System.Data; using System.Data.SqlClient; using System.Configuration; namespace ApComapaign { public partial class master : System.Web.UI.MasterPage { SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings[conn].ConnectionString); protected void Page_Load(object sender EventArgs e) { } protected void btn_search_Click(object sender EventArgs e) { //txtSearch.Text = Session[name].ToString(); Response.Redirect(search.aspx); } protected void Button1_Click(object sender EventArgs e) { } } } and i need search results in separate page so i take another page as search.aspx in search.aspx we have namespace ApComapaign { public partial class search1 : System.Web.UI.Page { SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings[conn].ConnectionString); protected void Page_Load(object sender EventArgs e) { SqlDataAdapter da = new SqlDataAdapter(select * from Candidate1 where name = '+Session[name].ToString()+' cn); DataSet ds = new DataSet(); da.Fill(ds); DataList1.DataSource = ds.Tables[0]; DataList1.DataBind(); } } }

Iftikar Hussain · Answer

Hi Where you have assigned the session variable Session[name] ? Can you share the complete code? Regards Iftikar

Sanjeeb Lenka · Answer

hi aditya Your datalist is present in child page or in master page. as my code is written for child page and both textbox and button should present in child page then it will work. why you use textbox in master page..

aditya immadi · Answer

Hai Sanjeeb my search box is in masterpage .actually i used generic handler for this the handler accepts request from JQuery in a Query string parameter  q . By passing query string parameter as search text and get user details based on that search text. when i tried your code it shows error as datalist1 is ot ffound in current contet DataList1.DataSource = ds.Tables[0]; DataList1.DataBind(); Thanks and Regards

Sanjeeb Lenka · Answer

hi try like this as you have to search on button click try like this. here i am providing code for search if user enter any name it will search and bind data if not it will bind all the data. 1st on pageload it will bind all the data. 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; using System.Data; using System.Configuration; public partial class _Default : System.Web.UI.Page { SqlConnection cn = new SqlConnection(ConfigurationManager.ConnectionStrings[conn].ConnectionString); protected void Page_Load(object sender EventArgs e) { if (!IsPostBack) { BindName(); } } protected void Button1_Click(object sender EventArgs e) { BindName(); } private void BindName() { SqlDataAdapter da; if (txtName.Text != string.Empty) da = new SqlDataAdapter(select * from Candidate1 where name = ' + txtName.Text + ' cn); else da = new SqlDataAdapter(select * from Candidate1 cn); DataSet ds = new DataSet(); da.Fill(ds); DataList1.DataSource = ds.Tables[0]; DataList1.DataBind(); } } try this code and i am little bit confuse why you use session for search as you have to search on textbox value

Prashant Yadav · Answer

make sure that u have value with Session object. put NULL Check.