Share DataSet between Forms

Question

I'm working on a Windows form application in Visual Studio 2010 Express. My Home form has one dataset with 4 tables. One of these tables is called "Category" and I want to manage this table from a separate form called Categories.

I followed the steps outlined by @Harm van der Haas in (Shared DataSet Over Multiple Forms C#) but I can't get it work.

In my Home form I have the following code:

public partial class frmHome : Form
{
    public DataSet _dsMain;

    public frmHome(DataSet dsMain)
    {
        _dsMain = dsMain;
        InitializeComponent();
    }

And in my program.cs I have:

static class Program
{
    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        DataSet DS = new DataSet();
        Application.Run(new frmHome(DS));
    }
}

And in my Category form I have the following code:

public partial class frmCategory : Form
{
    public DataSet ds2;
    public frmCategory(DataSet dsMain)
    {
        ds2 = dsMain;
        InitializeComponent();
    }

    private void frmCategory_Load(object sender, EventArgs e)
    {
        dgvCategory.DataSource = ds2;
        dgvCategory.DataMember = "Category";
        dgvCategory.Refresh();
    }
}

Here I launch the form Category:

private void btnStart_Click(object sender, EventArgs e)
{
    Globals.startTime = DateTime.Now;
    frmCategory frmC = new frmCategory(_dsMain);
    frmC.ShowDialog();
    //updateActiveTrans();
}

But when the Category form loads my datagridview on it dgvCategory doesn't show Category tables headers

Answer 1

Here is my simple way on how to pass Dataset from one form to another. I'm using Visual Studio 2012 C# WPF with PostgreSQL as Database.

        //ON MY FIRST FORM
        //this is my connection - add it anywhere you want
        //or change it according to your need
        NpgsqlConnection iConnect = new NpgsqlConnection("Server = " + myModule.Server + ";Port = " + myModule.Port + ";User ID = " + myModule.UserID + ";Password = " + myModule.Password + ";Database = " + myModule.Database);
        iConnect.Open();
        NpgsqlCommand iQuery = new NpgsqlCommand("Select * from Table1");
        iQuery.Connection = iConnect;
        NpgsqlDataAdapter iAdapter = new NpgsqlDataAdapter(iQuery);
        DataSet iDataSet = new DataSet();
        iAdapter.Fill(iDataSet, "SET");

        myModule.dtSet = iDataSet;//pass the dataset to myModule.cs

Then, click Project>>Add Class>>and rename it to myModule.cs

Then add the following code inside class myModule

        //This is the code for the DATASET shared
        static DataSet strDataset;
        //this is the catcher of DATASET info request...
        public static DataSet dtSet
        {
           get { return strDataset; }
           set { strDataset = value; }
        }

Now, this is how you will use the passed dataset on your second form.

    //MY SECOND FORM
    public Form2()
    {
        InitializeComponent();

        DataSet iDataSet = new DataSet();//set the instance of Dataset
        iDataSet = myModule.dtSet;       //get the data from myModule and pass it to iDataSet

    //now, you can use it here!
    }

That's it and happy coding! ^_^

Answer 2

Ok, I figured it out. I was passing the DataSet incorrectly from my home form. This is the code that ended up working for me.

In my home(main) form I created the constructor like so:

public partial class frmHome : Form
{
    public frmHome(DataSet dsMain)
    {
        InitializeComponent();
    }

In my Program.cs I did the following:

static void Main()
{
    Application.EnableVisualStyles();
    Application.SetCompatibleTextRenderingDefault(false);
    DataSet DS = new DataSet();
    Application.Run(new frmHome(DS));

And this is how I open my Category form. --the form where I need to remotely view and manage a table from my dsMain DataSet--

    frmCategory frmC = new frmCategory(dsMain);
    frmC.ShowDialog();

And in my Category form I passed my dsMain declared in my home form, I declared a new public DataSet ds2 and made it equal to dsMain.

public partial class frmCategory : Form
{
    public DataSet ds2;
    public frmCategory(DataSet dsMain)
    {
        ds2 = dsMain;
        InitializeComponent();
    }

And finally in my form load event I bound ds2 to my dataGridView like so:

private void frmCategory_Load(object sender, EventArgs e)
{
    dgvCategory.DataSource = ds2;
    dgvCategory.DataMember = "Category";
    dgvCategory.Refresh();

And it works like a charm now. I can view, edit and save my main DataSet from my Category form now. Thanks for the help @CharlesMighty, it helped a lot.

Answer 3

in you frmCategory_Load event when assigning the grid a datasource you need to specify the table that you need. Here is the sample code:

public partial class frmCategory : Form
{
public DataSet ds2;
public frmCategory(DataSet dsMain)
{
    ds2 = dsMain;
    InitializeComponent();
}

private void frmCategory_Load(object sender, EventArgs e)
{
    dgvCategory.DataSource = ds2.Tables[0]; //you can use .Tables[1] or the desired table
    dgvCategory.DataMember = "Category";
    dgvCategory.Refresh();
}

}