I cannot save

Israel

12y1.3kLearn iOS Programming

Hi!

When I am trying to save I receive this message:

Object reference not set to an instance of an object.

Please have a look to my whole code:

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

//using System.Data;

using System.Data.SqlClient;

namespace ElSoft_FactuStocks

{

public partial class Facturacao : Form

{

public Facturacao()

{

InitializeComponent();

}

//DataRowView drv;

System.Data.SqlServerCe.SqlCeConnection con;

System.Data.SqlServerCe.SqlCeDataAdapter da;

System.Data.SqlServerCe.SqlCeCommandBuilder cb;

DataSet ds1;

int MaxRows = 0;

int inc = 0;

private void btnSave_Facturacao_Click(object sender, EventArgs e)

{

DataRow dRow = ds1.Tables["facturacao"].NewRow();

dRow[1] = label10.Text;

/*dRow[1] = nomeClienteFactu.Text;

dRow[2] = artigoFactu.Text;

dRow[3] = leituraCodFactu.Text;

dRow[4] = quantidadeFactu.Text;

dRow[5] = precoFactu.Text;

dRow[6] = totalFactu.Text;*/

//dRow[7] = quantidadeFactu.Text;

//dRow[8] = quantidadeFactu.Text;

ds1.Tables["Facturacao"].Rows.Add(dRow);

System.Data.SqlServerCe.SqlCeCommandBuilder cb;

cb = new System.Data.SqlServerCe.SqlCeCommandBuilder(da);

cb.DataAdapter.Update(ds1.Tables["Facturacao"]);

MaxRows = MaxRows + 1;

inc = MaxRows - 1;

//btnAddNew.Enabled = true;

//btnSave.Enabled = false;

}

9 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes12y ago
Accepted answer
Well, assuming you're uncommenting the line which opens the connection before running that code, then I can't see anything wrong with it.

Does the connection string you're using work OK for reading data from the database?
Vulpes12y ago
Glad to hear you've sorted it out now :)
Israel12y ago
Excuse me Vulpes, I was very wrong in my codes. Firstly, I said that it's give a message saying "Saved". The I could say "Not saved". But now I check step by step my codes. I see that the problem was on my path: the wrong connection line code: string connstr = "database=master;server=.\\localhost\\sqlexpress;user=password="; the correct connection line code: string connstr = "Data Source=localhost\\sqlexpress;Initial Catalog=master;Integrated Security=True"; Many thanx.
Israel12y ago
huuuuuuuuuum, it's true!!!

Now I do simplify my code...But there's something little bit wrong in this code. It's running very well without error message. Then when I click to the button to save it's says "saved". In real NOT!

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
using System.Configuration;

namespace ElSoft_FactuStocks
{
public partial class ConsultasStocks : Form
{
public ConsultasStocks()
{
InitializeComponent();
}

SqlConnection conn;
SqlCommand comm;
string connstr = "database=master;server=.\\localhost\\sqlexpress;user=password=";

private void btnSave_ProdutoStock_Click(object sender, EventArgs e)
{
{
conn = new SqlConnection(connstr);
comm = new SqlCommand();
//conn.Open();

SqlParameter codigobarra = new SqlParameter("@codbarr", SqlDbType.NChar);
SqlParameter produto = new SqlParameter("@prod", SqlDbType.VarChar);
SqlParameter n_stocks = new SqlParameter("@nstock", SqlDbType.NChar);

comm.Parameters.Add(codigobarra);
comm.Parameters.Add(produto);
comm.Parameters.Add(n_stocks);

codigobarra.Value = codigoBarraStocks.Text;
produto.Value = produtoStocks.Text;
n_stocks.Value = nStocksStocks.Text;

comm.Connection = conn;

comm.CommandText = "insert into consultoria values(@codbarr,@prod,@nstock)";

try
{
comm.ExecuteNonQuery();
MessageBox.Show("saved");

codigoBarraStocks.Clear();
produtoStocks.Clear();
nStocksStocks.Clear();
}
catch (Exception)
{
MessageBox.Show("Not saved");
}
finally
{
//conn.Close();

}
}
}
}
}
Vulpes12y ago
This is a different point to the one you raised previously.

The reason why this connection string isn't working:

con.ConnectionString = "Data Source=localhost\\sqlexpress;Initial Catalog=master;Integrated Security=True";

is because you're using the in-memory database SQL Server Compact Edition, not SQL Server Express.

The System.Data.SqlServerCe namespace contains all the classes for the Compact Edition.
Israel12y ago
ok, let do it step by step. Because I realize that my path must be wrong.
Why I am saying like that just because when I put this line to test if its gone to fetch records. Its works:

con.ConnectionString = "DataSource=c:\\Users\\INAC\\Documents\\Employees.sdf";

this line doesnt works:
con.ConnectionString = "Data Source=localhost\\sqlexpress;Initial Catalog=master;Integrated Security=True";

Let go slowly because I need your help to resolv it (I passed night without sleep for that).

Then the line that works is inside here in blue:

private void ConsultasStocks_Load(object sender, EventArgs e)
{
con = new System.Data.SqlServerCe.SqlCeConnection();
//con.ConnectionString = "Data Source=localhost\\sqlexpress;Initial Catalog=master;Integrated Security=True";

con.ConnectionString = "DataSource=c:\\Users\\INAC\\Documents\\Employees.sdf";

ds1 = new DataSet();

string sql = "SELECT * from consultoria";
da = new System.Data.SqlServerCe.SqlCeDataAdapter(sql, con);
da.Fill(ds1, "consultoria");
NavigateRecords();

}
//these lines also I can see records on my textboxs without problem
private void NavigateRecords()
{
DataRow dRow = ds1.Tables["consultoria"].Rows[inc];
codigoBarraStocks.Text = dRow.ItemArray.GetValue(1).ToString();
produtoStocks.Text = dRow.ItemArray.GetValue(2).ToString();
nStocksStocks.Text = dRow.ItemArray.GetValue(3).ToString();

MaxRows = ds1.Tables["consultoria"].Rows.Count;
}
Now, I understood that it's my path. But I go to copy the right connection string that doesnt work straight from the properties and pasted in the load event. But it's doesnt works.
Only this works as I said:
con.ConnectionString = "DataSource=c:\\Users\\INAC\\Documents\\Employees.sdf";
Vulpes12y ago
It looks like the problem lies with this line:

DataRow dRow = ds1.Tables["facturacao"].NewRow();

When you filled the DataTable, you called it "workers" rather than "facturacao":

da.Fill(ds1, "workers");

So if you change the last line to:

da.Fill(ds1, "facturacao");

it should get rid of the exception.

You've also closed the connection in the Load handler and so will need to reopen it again (or not close it in the first place) to update the database.
Israel12y ago
Ok, now you have the whole codes. Thanx!

Hi!

When I am trying to save I receive this message:
Object reference not set to an instance of an object.

Please have a look to my whole code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
//using System.Data;
using System.Data.SqlClient;
namespace ElSoft_FactuStocks
{
public partial class Facturacao : Form
{
public Facturacao()
{
InitializeComponent();
}
//DataRowView drv;
System.Data.SqlServerCe.SqlCeConnection con;
System.Data.SqlServerCe.SqlCeDataAdapter da;
System.Data.SqlServerCe.SqlCeCommandBuilder cb;
DataSet ds1;
int MaxRows = 0;
int inc = 0;

private void btnSave_Facturacao_Click(object sender, EventArgs e)
{
DataRow dRow = ds1.Tables["facturacao"].NewRow();
dRow[1] = label10.Text;
/*dRow[1] = nomeClienteFactu.Text;
dRow[2] = artigoFactu.Text;
dRow[3] = leituraCodFactu.Text;
dRow[4] = quantidadeFactu.Text;
dRow[5] = precoFactu.Text;
dRow[6] = totalFactu.Text;*/
//dRow[7] = quantidadeFactu.Text;
//dRow[8] = quantidadeFactu.Text;
ds1.Tables["Facturacao"].Rows.Add(dRow);
System.Data.SqlServerCe.SqlCeCommandBuilder cb;
cb = new System.Data.SqlServerCe.SqlCeCommandBuilder(da);
cb.DataAdapter.Update(ds1.Tables["Facturacao"]);
MaxRows = MaxRows + 1;
inc = MaxRows - 1;
//btnAddNew.Enabled = true;
//btnSave.Enabled = false;
}

private void Facturacao_Load(object sender, EventArgs e)
{
con = new System.Data.SqlServerCe.SqlCeConnection();
con.ConnectionString = "Data Source=localhost\\sqlexpress;Initial Catalog=master;Integrated Security=True";
con.Open();
ds1 = new DataSet();

string sql = "SELECT * From facturacao";
da = new System.Data.SqlServerCe.SqlCeDataAdapter(sql, con);
da.Fill(ds1, "workers");
//NavigateRecords();

con.Close();
}
Vulpes12y ago
I think there must be more code in your application than you've posted as I can't see where you've initialized the fields 'con' , 'ds1' or 'da'. Nor can I see where you've created the DataTable, facturacao, and added it to the DataSet's Tables collection.

So there are plenty of candidates for being null here.