Object reference not set to an instance of an object.

Question

1.00/5 (1 vote)

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SQL-Server-2005

, +

hi friends
i bind dropdown and generate this error Object reference not set to an instance of an object.
and my code is

C#

if (!IsPostBack)
        {
           bind_drop_down_degree();
        }
protected void bind_drop_down_degree()
    {
        DropDownList ddldegree = gvOtherDegree.FindControl("ddl_degree") as DropDownList;
        Property_degree_master pdm = new Property_degree_master();
        pdm.faculty_id = 1;
        DataTable dt_degreess = new DataTable();
        dt_degreess = BAL_Employee.bind_degree_by_faculty_id_test_tesdt(pdm);
        ddldegree.DataSource = dt_degreess;
        ddldegree.DataTextField = "degree_name";
        ddldegree.DataValueField = "degree_id";
        ddldegree.DataBind();
    }

public static DataTable bind_degree_by_faculty_id_test_tesdt(Property_degree_master pdm)
    {
        SqlCommand cmd = new SqlCommand();
        CreatePara para = new CreatePara();
        cmd.CommandText = "get_degree_byfaculty_sp";
        cmd.Parameters.Add(para.IntInputPara("@faculty_id",pdm.faculty_id));
        DataTable dt = CreateCommand.ExecuteQuery(cmd);
        return dt;
    }

plz help me whats a problem

Posted 26-May-13 19:58pm

Rashmikants Monpara

Updated 26-May-13 20:00pm

Sridhar Patnayak

v2

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Comments

KK Kod 27-May-13 2:02am

In which line you are getting the error .. would you mind posting the stack trace .. so that we can diagnose properly .

[no name] 27-May-13 2:11am

this line to gate error ddldegree.DataSource = dt_degreess;

[no name] 27-May-13 2:05am

this line to gate error
ddldegree.DataSource = dt_degreess;

KK Kod 27-May-13 2:22am

check dt_degreess has got data using quick watch.whether your method BAL_Employee.bind_degree_by_faculty_id_test_tesdt(pdm); is returning null.

KK Kod 27-May-13 2:23am

i wanted to know that is that method returning data table with data or null

[no name] 27-May-13 2:30am

i check
dt_degreess = BAL_Employee.bind_degree_by_faculty_id_test_tesdt(pdm);
and dt_degreess are fetch data

2 solutions

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KK Kod · Answer 1 · 2013-05-26T21:37:00

C#

if (!IsPostBack)
        {
           bind_drop_down_degree();
        }
protected void bind_drop_down_degree()
    {
        int rowNum=2;
		int colNum=1;
		/*
	      Some time you will not be getting the ddl_degree  control from the grid view 
		  so try this code to get the control from the grid view
		*/
		DropDownList ddldegree = (DropDownList)gvOtherDegree.Rows[rowNum].Cells[colNum].FindControl("ddl_degree");
        Property_degree_master pdm = new Property_degree_master();
        pdm.faculty_id = 1;
        DataTable dt_degreess = new DataTable();
        dt_degreess = BAL_Employee.bind_degree_by_faculty_id_test_tesdt(pdm);
        ddldegree.DataSource = dt_degreess;
        ddldegree.DataTextField = "degree_name";
        ddldegree.DataValueField = "degree_id";
        ddldegree.DataBind();
    }
 
public static DataTable bind_degree_by_faculty_id_test_tesdt(Property_degree_master pdm)
    {
        SqlCommand cmd = new SqlCommand();
        CreatePara para = new CreatePara();
        cmd.CommandText = "get_degree_byfaculty_sp";
        cmd.Parameters.Add(para.IntInputPara("@faculty_id",pdm.faculty_id));
        DataTable dt = CreateCommand.ExecuteQuery(cmd);
        return dt;
    }

If you have got ddl_degree control placed in all populated row of the grid view
loop through the grid view

C#

foreach (gvOtherDegree row in gvOtherDegree.Rows)
      {
          DropDownList ddldegree = (DropDownList)row.FindControl("ddl_degree");
          ddldegree.DataSource = dt_degreess;
          ddldegree.DataTextField = "degree_name";
          ddldegree.DataValueField = "degree_id";
          ddldegree.DataBind();
      }

OriginalGriff · Answer 2 · 2013-05-26T20:12:00

Solution 1

As you are getting the error on the line

C#

ddldegree.DataSource = dt_degreess;

And it is the first reference to ddldegree after the declaration:

C#

DropDownList ddldegree = gvOtherDegree.FindControl("ddl_degree") as DropDownList;

Then either "ddl_degree" does not exist as a findable control, or it is not created as a DropDownList. Either one would give you a null value and cause the error.

Check your control name, and then check it has "runat=server" in it's definition.

Posted 26-May-13 20:12pm

OriginalGriff

Comments

[no name] 27-May-13 2:21am

my asp. code is
<asp:DropDownList runat="server" ID="ddl_degree" Style="width: 150px; border: solid 1px #C9C9C9;
margin-left: ">
<asp:ListItem Value="0">Select Degree

and ddl_degree is correct