Data Binding Using DataGrid

hoailing22 · June 6th, 2005, 10:38 PM

Hi, I have a dropdownlist for category selection. after the selection, the data that is in the category selected should be displayed.

But the problem is, when I selected any category, all the data in the table is displayed regardless which category is selected. For example, there are 4 categories, books, journals, magazines n others. When I select any of these, it displayed all the categories. i only want it to display the particular category i choose, not all.

Code:

  Private Sub ddlView1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ddlView1.SelectedIndexChanged
        Dim Str As String
        Str = "Select * From Library where CategoryID = '" & ddlView1.SelectedValue
        SqlDataAdapter1.Fill(DsLIbrary1)
        DataGrid1.DataSource = DsLIbrary1
        DataGrid1.DataBind()
End Sub

Another problem is, it don't allow paging to be done even though i set allow paging= true in the properties for the dropdownlist.

Code:

Private Sub DataGrid1_PageIndexChanged(ByVal sender As System.Object, ByVal e As System.Web.UI.WebControls.DataGridPageChangedEventArgs) Handles DataGrid1.PageIndexChanged
        DataGrid1.CurrentPageIndex = e.NewPageIndex
        DataGrid1.DataBind()
End Sub

Anyone can help? Thanks!

Irene

r_ganesh76 · June 7th, 2005, 12:20 AM

Have you given AutoPostBack to true??

Can u send the htm portion of the drown??

Regards
Ganesh

hoailing22 · June 7th, 2005, 12:41 AM

I set auto postback to true already.

Code:

<asp:dropdownlist id="ddlView1" style="Z-INDEX: 104; LEFT: 344px; POSITION: absolute; TOP: 56px" runat="server"
                ForeColor="Black" Height="32px" Width="168px" AutoPostBack="True">
                <asp:ListItem Value="1">Books</asp:ListItem>
                <asp:ListItem Value="2">Journals</asp:ListItem>
                <asp:ListItem Value="3">Magazines</asp:ListItem>
                <asp:ListItem Value="4">Others</asp:ListItem>
            </asp:dropdownlist>

Prashant.k.m · June 7th, 2005, 12:52 AM

HI,
Have you must corected a problem in this line,

Str = "Select * From Library where CategoryID = '" & ddlView1.SelectedValue

opened single quote which may not be required as the field is an ID

Also be sure you a are not reloading the whole grid & dropdowm in every post back

Prashant

hoailing22 · June 7th, 2005, 03:08 AM

I delete the single quote already. But it still display the same result.
when I generate the dataset, I select the data from all 4 categories.

What should I do to make sure I don't reload the whole grid n dropdownlist
in every post back?

Prashant.k.m · June 7th, 2005, 03:48 AM

Hi,

You should check Not IsPostback in you page load before loading

Prashant

hoailing22 · June 7th, 2005, 05:17 AM

I feel that even though I retrieve the CategoryID from str statement,
I don't pass the value to display the data after search, am I right?

I should not call the databind() in page load, else the data will be displayed
once the page is loaded, rite?

I still can't figure out how to solve this problem.

Can somebody help me? Thanks!

planoie · June 7th, 2005, 11:38 AM

There is a basic problem here...

Private Sub ddlView1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ddlView1.SelectedIndexChanged
        Dim Str As String
        Str = "Select * From Library where CategoryID = '" & ddlView1.SelectedValue
        SqlDataAdapter1.Fill(DsLIbrary1)
        DataGrid1.DataSource = DsLIbrary1
        DataGrid1.DataBind()
End Sub

Where is the new query (Str) ever getting assigned to the data adapter? All you are doing is reloading the original query that was created for you by the data adapter wizard.

You need to assign the new query to the data adapter select command property:

        SqlDataAdapter1.SelectCommand.CommandText = Str
        SqlDataAdapter1.Fill(DsLIbrary1)

-Peter

hoailing22 · June 7th, 2005, 11:27 PM

Now I can view the data for the particular category i choose, but i still
can't navigate through the records. i.e, I hv 143 records, I set 1 page to display 10 records.
the problem is here.. when i click the 2nd page onwards, it does not display any data.

Code:

Private Sub DataGrid1_PageIndexChanged(ByVal sender As System.Object, ByVal e As System.Web.UI.WebControls.DataGridPageChangedEventArgs) Handles DataGrid1.PageIndexChanged
        DataGrid1.CurrentPageIndex = e.NewPageIndex
        DataGrid1.DataBind()
End Sub

even though i debug, it does not display any error.
Can anybody help me? Thanks!

spacy · June 8th, 2005, 12:54 AM

You are binding the grid using DataGrid1.DataBind(). But you have not
specified the data to bind.

    Private Sub DataGrid1_PageIndexChanged(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridPageChangedEvent Args) Handles DataGrid1.PageIndexChanged
        DataGrid1.CurrentPageIndex = e.NewPageIndex
        BindGrid()
    End Sub

//make the relevant changes as per your requirement
Private Sub BindGrid()
        Dim cnn As SqlConnection
        Dim da As SqlDataAdapter
        Dim ds As New DataSet()

        cnn = New SqlConnection(ConfigurationSettings.AppSettings(). Item("ConnectionString"))
        da = New SqlDataAdapter("select lastname,firstname,city from employees", cnn)
        da.Fill(ds, "employees")

        DataGrid1.DataSource = ds
        DataGrid1.DataMember = "employees"
        DataGrid1.DataBind()

    End Sub