Removing items from a datagrid???

[Ironsmith1977]

I set the DataKeyFields in code actually, until run time, the DataGrid displays nothing with no column headers or anything. Only after Items are selected will the grid populate. The only static field in the grid is the "Remove" column, which is holding checkboxes. Take care Ironsmith

[minhpc_bk]

Hi Ironsmith, I'm back, is it working now?

[Ironsmith1977]

Hello, No its not. I think from what others have told me, it's because I don't have a unique identifier column. None of the columns in my table are unique, I don't have a "ItemID" column or any other numbering system in the DataGrid. Therefore, trying to specify what row to delete, has been the main problem. If you check out my first post in this thread, I posted my code. It hasn't changed much since I posted that. Take care Ironsmith

[minhpc_bk]

Well in this case, IMO there are a few options here: + You have to re-design the table schema in order that there is a way to select a specific row in a table, I mean it should have a unique column. + You can select the row by its index. I mean if you select the second row in the grid to delete, then at the server side you can delete the second row in the data table. However, this is not recommended as if you use paging, the index might not be correct when you are in another page orher than 1.

[Ironsmith1977]

Is there a way to create a column that AutoIncrements? Or is there a way that I can hard code in row numbers? However, since I'll never know exactly how many rows there will be in the DataGrid, that's most likely not a good idea. Well, unless I can AutoIncrement a column somehow, I guess I'll just have to leave it as is, it deletes the first row. lol. Horrible, but I'm running out of time. Take care Ironsmith

[minhpc_bk]

It's very simple to create an autoincrement column, take a quick look at the sample code below:

DataColumn itemIDCol = dataTable.Columns.Add("ItemID", typeof(Int32));
itemIDCol.AutoIncrement = true;
itemIDCol.AutoIncrementSeed = 0;
itemIDCol.AutoIncrementStep = 1;

This column starts with a value of 0 and adds incrementally in steps of 1. For more information, see Creating AutoIncrement Columns[^] DataColumn Class[^]

[Ironsmith1977]

Oh that is awesome, I just did it and it works great. Good to know that I'm not completely screwed! Thank you very much! I'm back to the same problem, but I now have a unique identifier column. I just keep getting that "Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index" exception error. Any thoughts? Take care Ironsmith

[minhpc_bk]

I just did it and it works great Sound better, :) Can you post here what line is causing that error?

[Ironsmith1977]

This is where it stops:

string id = PurchaseDataGrid.DataKeys[index] as string;

I've tried altering [index], but that didn't work out so well. I've stepped through the code, and really I can't see why this code doesn't work. But this is the first time I'm using this sort of code, not to mention I just started ASP.NET(C#) a few weeks ago. Take care Ironsmith

[minhpc_bk]

That's what I'm expecting, do you set the DataGrid.DataKeyField property? , here is the sample code:

private void Page_Load(object sender, System.EventArgs e)
{
if(!IsPostBack)
{
DataTable table = CreateDataSource();

    //The ItemID is used as a key to select a specific row in a table.  
    //You may probably replace it with your real column name.
    PurchaseDataGrid.DataKeyField = "ItemID";
                        
    PurchaseDataGrid.DataSource = table;
    PurchaseDataGrid.DataBind();
                   
    Session\["Items"\] = table;
 }

}

In addition, you can also set this property in the design window.

[Ironsmith1977]

Well, I had that line of code in the wrong section...I had it in the click event, not the page load. But, it's progress, it got past that line and down to the next where it generated this exception error: "Cannot perform '=' operation on System.Int32 and System.String." This is the line of code:

DataRow[] rows = dt.Select("ItemID='"+ id + "'");

One thing is for certain, I'm learning more here from you than I have from my instructor all year! lol. Ironsmith

[minhpc_bk]

I also guess this reason then I post all code in the Page_Load event. The key thing is to set that property before the datasource is really bound to the datagrid. Because at binding time, the DataKeys collection will be constructed based on the DataKeyField. If the ItemID column is of the Integer type, you simply remove the apostrophes in code, it will look like this:

DataRow[] rows = dt.Select("ItemID="+ id);

[Ironsmith1977]

The ItemID column is of Integer type, but when I take out the apostrophes I get a "Syntax error: Missing operand after '=' operator." error. On the line of code:

DataRow[] rows = dt.Select("ItemID="+ id);

Take care Ironsmith

[minhpc_bk]

Oh , I'm missing one thing. Because the ItemID column is of Integer type, then the code :

string id = PurchaseDataGrid.DataKeys[index] as string;

should be replaced by :

int id = (int) PurchaseDataGrid.DataKeys[index];

sorry about that, it should be working now.

[Ironsmith1977]

OH MY GOD, it's working!!! lmfao! Thank you so much my friend, I will be singing your praises for weeks. lmfao. Take care Ironsmith

[minhpc_bk]

Well-done Ironsmith, :beer: :) Good luck to you.