Can't update data in datagridview

J T

Goal:
Having two buttons that should be enable to add or delete data from datagridview. The changes should be make in real time so you should be see the new result.

Problem:
Having problem to display the new result after I have used button add functionality because the result won't display in real time. In order to view the result I have to close and reopen the application in order to view the new result.

Please remember that I don't use a database.

I'm using class table and then I connect the table to the datagridview's datasource.

// JT

            DataTable table = new DataTable();
            table.Columns.Add("a");
            table.Columns.Add("b");

            foreach (var a in myManagerProduct.GetAllProductList())
            {

                    DataRow row;
                    row = table.NewRow();

                    row["a"] = a._articleNumber;
                    row["b"] = a._name;
                    dgridStock.Rows.Add(row);

                    table.Rows.Add(row);
            }

            dgridStock.DataSource = table;

12 Replies

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

Sam Hobbs15y ago
The following will quickly show you an alternative. If you create a new (forms) project, then this can be done in a few minutes literally.
After creating the project, in Solution Explorer, add a DataSet (Right-click on project then Add | New Item | Visual C# Items | Data | DataSet).
In the toolbox, drag a DataTable to the DataSet. Right-click on the DataTable and add columns.
Go to the form designer. From the Data Sources window, drag the datatable to the form. By default, a DataGridView will be created for the DataTable.
Build and test the program. You can add, update and delete records right in the DataGridView. The data won't be saved when you close the form but we have not provided a place to save it.
End of demonstration.
See my Database Table Update in a DataGridView without Writing Code for a little help for saving the data. If you simply must have buttons for adding and deleting records, then that could be done.
J T15y ago
Yes, I tried refreshing but the problem still occur :S
Vulpes15y ago
I don't understand that at all but as your version worked OK when I tried it I don't think it can be the problem anyway.

Have you tried refreshing the grid after making the deletions?

dgridStock.Refresh();
J T15y ago
It's value that gave null
Suthish Nair15y ago

DataGridView - Insert, Update, Delete and Retrieve records using stored procedure
Vulpes15y ago
I don't understand how that error can occur when it didn't occur in your previous code :-/

All we're really doing is iterating through the selected items in the reverse direction and since you're not using a database it's difficult to see how anything can be null.

Can you tell from the debugger which object reference is null here?

Incidentally, I tried (a suitably adjusted version of) both your original code and my code and they both ran fine, updating the DGV immediately!
J T15y ago
I tried your solution and in the code "string articleNumber = a.Cells[0].Value.ToString();" I retrieve a error message that is "Object reference not set to an instance of an object."
Vulpes15y ago
Well, one problem here is that you're deleting rows from the SelectedRows collection whilst iterating through it using 'foreach' which can mess up the indexing of the subsequent elements to be examined.

I'd try iterating backwards through the collection using a 'for' statement instead which shouldn't affect the indexing:

for (int i = dgridStock.SelectedRows.Count - 1; i >= 0; i--)
{
   DataGridViewRow a = dgridStock.SelectedRows[i];
   string articleNumber = a.Cells[0].Value.ToString();
   string name = a.Cells[1].Value.ToString();
   myDeleteProduct.DisplayingADeleteMessagePopup(articleNumber, name);
   dgridStock.Rows.Remove(a);
}

dgridStock.Refresh(); // if necessary
J T15y ago
            DeleteProduct myDeleteProduct = new DeleteProduct();

            foreach (DataGridViewRow a in dgridStock.SelectedRows)
            {
                string articleNumber = a.Cells[0].Value.ToString();
                string name = a.Cells[1].Value.ToString();

                myDeleteProduct.DisplayingADeleteMessagePopup(articleNumber, name);

                dgridStock.Rows.Remove(a);


            }

Sourcecode för button:

            myNewProduct = new NewProduct();
            myNewProduct.ShowDialog();

AFter showdalog you go back to method UpDateGUI(). THe sourcode to this method is located in the first message in this discusstion.
Vulpes15y ago
I imagine that the code you've posted is for populating the DGV initially.

If so, can you post the code you're using for adding or deleting a row please.
J T15y ago
I already tried it but no changes would occur
Vijay Yadav15y ago
Hi,
On delete button, after deletig record again call the function that populate the datagridview with data and your query will get solved.:)