filter dataview on datagrid in datalist

datalist , asp.net , datagrid , rowfilter United States
  • 8 years ago

    I had a setup where I had a datalist of course listings, and when the items were created I went out to a remote sql server and retrieved the faculty for each course. But, that seems to take too long to load, so I thought it would be faster to go get all the data at once on page load and then filter with data views. But, I can't seem to get there. I tested on a datagrid outside the datalist and it populates with 3 rows fine. (Number one - is my assumption correct? Number two - what am I doing wrong? Is the Public Data.dataView not available when I'm trying to call it?)

    It stops on the line 'dv.RowFilter = "eid=" & myEID.ToString with the error: Object reference not set to an instance of an object.

    If I comment out the line, I get no datagrids.

    Imports dsList
    Partial Class orpce_hcClasses
        Inherits System.Web.UI.Page
        Public ds As New Data.DataSet
        Public myFacView As Data.DataView
        Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
            If Not Page.IsPostBack Then
                Dim myList As dsSql = New dsSql()   ''''instantiate the function to get dataset
                Dim myView As Data.DataView
                Dim myStr As String = ""
                ds = myList.dsListAll(go get the initial course datalist dataset)
                If ds.Tables("list").Rows.Count > 0 Then
                    myView = ds.Tables("list").DefaultView
                    dlList.DataSource = myView
                    myView.Sort = "startSort"
                    dlList.DataBind()
                    If ds.Tables("list").Rows.Count > 0 Then
                        Dim i As Integer
                        For i = 0 To ds.Tables("list").Rows.Count - 1
                            myStr &= ds.Tables("list").Rows(i)("eid").ToString & ","
                        Next
                        myStr = Left(myStr, Len(myStr) - 1)
                    End If
                    ds = myList.dsListFac(myStr)
                    myFacView = New Data.DataView
                    myFacView = ds.Tables("faculty").DefaultView
                End If
            End If
        End Sub
    
        Protected Sub dlList_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.DataListItemEventArgs) Handles dlList.ItemDataBound
            Dim myEID As String = Convert.ToInt32(CType(e.Item.FindControl("txtEID"), TextBox).Text)
            Dim dv As Data.DataView
            Dim dg As DataGrid = CType(e.Item.FindControl("dgFac"), DataGrid)
            dv = myFacView
            'dv.RowFilter = "eid=" & myEID.ToString
            dg.DataSource = dv
            dg.DataBind()
        End Sub
    

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