Help checking for empty dataset

Payback · January 21st, 2005, 12:47 PM

I have an Access database with items from a collection stored in it. Each item is in one of four catagories and the datagrid shows the items in a specific catagory based on a drop down list selection. Sometimes there won't be anything in a specific catagory like "For Sale" and I don't want to show a datagrid header with nothing in the datagrid (this is what my page is doing now). I am coding everything by hand; I don't use VS.NET.

Here is my function which is part of a namespace that I have compiled:

Code:

Public Function GetBalisongList(strStatus as string, strSort as string) as Dataset
    If strStatus = "complete" Then
        strSQL = "SELECT BalisongID, make, model, status FROM balisong ORDER BY " & strSort
    Else
        strSQL = "SELECT BalisongID, make, model, status FROM balisong WHERE status = '" & strStatus & "' ORDER BY " & strSort
    End If
    Dim objConnection as New OLEDBConnection(m_DSN)
    Dim objDataAdapter as New OLEDBDataAdapter(strSQL, objConnection)
    Dim BalisongList as new Dataset()
    objDataAdapter.Fill(BalisongList)
    Return BalisongList
End Function

Here is the sub that handles the drop down list in my code behind page:

Code:

Public Sub balisongfilter(sender as object, e as eventargs)
    ViewState("status") = ddl_balisong.SelectedItem.Value
    If ViewState("status") = "description" Or ViewState("status") = "" Then
        lblinstructions.visible = true
        dgBalisongList.visible = false
        rptBalisongDetails.visible = false
    Else
        strSort = "make, model"
        Dim BalisongStatusList as new Balisong(strconnect)
        dgBalisongList.DataSource = BalisongStatusList.GetBalisongList(ViewState("status"), strSort)
        dgBalisongList.DataBind()
        lblinstructions.visible = false
        dgbalisonglist.visible = true
        rptBalisongDetails.visible = false
    End If
End Sub

I am trying to display an asp:label saying something like, "I do not currently have any balisongs for sale." instead of an empty datagrid. Thank you in advance for any help you can provide.

planoie · January 21st, 2005, 02:31 PM

I think what you want is to test if the DataTable in the DataSet is empty:

DataSet.Tables(0).Rows.Count = 0

Or you could test the grid after it's bound:

DataGrid.Items.Count = 0

-Peter

Vadivel · January 21st, 2005, 11:11 PM

if (ds == null) --- ds == dataset object

Best Regards
Vadivel

MVP ASP/ASP.NET
http://vadivel.thinkingms.com

mehdi62b · January 24th, 2005, 03:46 AM

Quote:

quote:Originally posted by Vadivel
if (ds == null)

and its VB.NET equivalent code is,

Code:

if(ds Is Nothing)...
End If

(ds=Nothing is incorrect but in C# ds==null is correct!?)

_____________________________
Mehdi.
software engineering student.
Looking for a good job for summer 2005.

mehdi62b · January 24th, 2005, 04:04 AM

I think for comparing two objects and values,

Code:

//C#
if(Obj1==Obj2)
if(Value1==Value2)
'VB.NET
if(<s>Obj1=Obj2</s>)'incorrect
if(Obj1 Is Obj2)
if(Value1=Value2)

_____________________________
Mehdi.
software engineering student.
Looking for a good job for summer 2005.

mehdi62b · March 28th, 2005, 05:00 AM

Code:

if (ds == null || ds.Tables[0].Rows.Count == 0){}

if ds is null,there will be no check for the next condition so there would be no null reference exception.

_____________
Mehdi.
software student.