Object reference not set to an instance of an object error in winform devexpress ?

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Hi,
I have Gridview in my Form, If i click button on the Gridview I get Column value of Focused Row and Try to use that Value in next Form. But in that new form error shown like this

C#

public partial class New_Invoice : DevExpress.XtraEditors.XtraForm
   {

       string getOper = "A";

       public New_Invoice()
       {
           InitializeComponent();
       }

       public New_Invoice(string oper, int invoiceno)
       {
           // TODO: Complete member initialization

           textEdit5.Text = invoiceno.ToString(); // error shown in this line
           textEdit5.Visible = false;
           getOper = oper;
       }

Whats wrong in my code ?

Posted 5-Nov-13 23:57pm

srihari1904

Updated 4-Nov-19 22:18pm

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Comments

Thomas ktg 6-Nov-13 6:04am

What is invoiceno? Does it bring any value or just gives null value? Check that too.

srihari1904 6-Nov-13 6:33am

it bring value from previous Form <pre lang="c#">private void repositoryItemButtonEdit1_ButtonClick(object sender, DevExpress.XtraEditors.Controls.ButtonPressedEventArgs e)
{
string oper = "A";

New_Invoice frm = new New_Invoice(oper, Convert.ToInt32(gridView1.GetFocusedRowCellValue("invoive_number")));
frm.Show();
gridView1.RefreshData();
}</pre>

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OriginalGriff · Accepted Answer · 2013-11-06T00:06:00

Solution 1

You haven't constructed the controls yet!
Either call InitializeComponent inside all your constructors, or reference the default constructor that does have it first by using construction chaining:

C#

public partial class New_Invoice : DevExpress.XtraEditors.XtraForm
    {

        string getOper = "A";

        public New_Invoice()
        {
            InitializeComponent();
        }

        public New_Invoice(string oper, int invoiceno) : this()
        {
            // TODO: Complete member initialization

            textEdit5.Text = invoiceno.ToString(); 
            textEdit5.Visible = false;
            getOper = oper;
        }

Posted 6-Nov-13 0:06am

OriginalGriff

Comments

srihari1904 6-Nov-13 6:28am

Hi OriginalGriff,
Now I changed error not shown but it shown Form with Empty Fields means it wont took Column value i think so ?

OriginalGriff 6-Nov-13 6:39am

Show the actual code you are using!

srihari1904 6-Nov-13 6:59am

private void repositoryItemButtonEdit1_ButtonClick(object sender, DevExpress.XtraEditors.Controls.ButtonPressedEventArgs e)
{
string oper = "A";

New_Invoice frm = new New_Invoice(oper, Convert.ToInt32(gridView1.GetFocusedRowCellValue("invoice_number")));
frm.Show();
gridView1.RefreshData();
}
this code in form 1 and this code in Form 2

public partial class New_Invoice : DevExpress.XtraEditors.XtraForm
{

string getOper = "A";

public New_Invoice()
{
InitializeComponent();
}

public New_Invoice(string oper, int invoive_number)
: this()
{
// TODO: Complete member initialization
//this.oper = oper;
//this.p = p;
textEdit5.Text = invoive_number.ToString();
textEdit5.Visible = false;
getOper = oper;
}
private void New_Invoice_Load(object sender, EventArgs e)
{
OleDbConnection con = new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:/Srihari/OrionSystem.accdb");

int i = Convert.ToInt32(textEdit5.Text);

OleDbCommand da = new OleDbCommand("select * from invoice_top where invoice_number='" + i + "' ", con);
con.Open();
OleDbDataReader reader = da.ExecuteReader(); // now error shown as "Data type mismatch"
while (reader.Read())
{

textEdit12.Text = reader.GetString(1);
textEdit13.Text = reader.GetString(2);
textEdit4.Text = reader.GetString(3);

textEdit1.Text = reader.GetString(5);
textEdit2.Text = reader.GetString(6);
textEdit3.Text = reader.GetString(7);

}

con.Close();
}

OriginalGriff 6-Nov-13 7:18am

Well, I'm not that surprised you get "data type mismatch" - try this instead:
OleDbConnection con = new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:/Srihari/OrionSystem.accdb");

int i = Convert.ToInt32(textEdit5.Text);

OleDbCommand da = new OleDbCommand("SELECT * FROM invoice_top WHERE invoice_number=@IN, con);
da.Parameters.AddWithValue("@IN", i);
con.Open();
OleDbDataReader reader = da.ExecuteReader();
And (assuming your invoice_number column is an integer) that should work - it is a bad idea to concatenate strings to form SQL commands, it leaves you open to SQL Injection attacks. Always use parametrised queries.