Question

So here’s the scenario – I started by querying data from tables transactions and v_patients. I execute that query to a List(Of transaction). I manipulate (Concat(), GroupBy(), etc.) that list until I reach a final projection and DataBind() to GroupMatchListView. I have some LinkButtons in the markup that have Sort commands. Now I need to write something in the GroupMatchListView_Sorting event handler that sorts the list. I think I need to use either an IComparer, or GroupMatchListView.Items.OrderBy somehow to sort the ListView, but I’m baffled. I do not want to run another SQL Query and redo my list manipulations. Thanks for any help!

The final projection:

Dim goliath = From f In wholeResults _
                          Group f By f.v_patient Into Group _
                          Order By v_patient.last_name, v_patient.first_name, v_patient.date_of_birth _
                          Select New With {.PatientID = v_patient.patient_id, .LastName = v_patient.last_name, .FirstName = v_patient.first_name, _
                             .DOB = v_patient.date_of_birth, .Ins = v_patient.insname, .MatchCount = Group.Count(), .Matches = Group}

            GroupMatchListView.DataSource = goliath
            GroupMatchListView.DataBind()

I have some buttons that have sort commands:

<th id="Th4" runat="server" style="width: 100px" width="100px">
                                        <asp:LinkButton ID="SortLastNameButton" runat="server" CommandName="Sort" CommandArgument="LastName" ForeColor="White">Last Name</asp:LinkButton>
                                    </th>
                                    <th id="Th5" runat="server" style="width: 100px" width="100px">
                                        <asp:LinkButton ID="SortFirstNameButton" runat="server" CommandName="Sort" CommandArgument="FirstName" ForeColor="White">First Name</asp:LinkButton>
                                    </th>
                                    <th id="Th6" runat="server" style="width: 85px" align="center" width="85px">
                                        <asp:LinkButton ID="SortDOBButton" runat="server" CommandName="Sort" CommandArgument="DOB" ForeColor="White" ToolTip="Date of Birth">DOB</asp:LinkButton>
                                    </th>
                                    <th id="Th7" runat="server" style="width: 185px" width="185px">
                                        <asp:LinkButton ID="SortInsuranceButton" runat="server" CommandName="Sort" CommandArgument="Ins" ForeColor="White">Insurance</asp:LinkButton>
                                    </th>

The place where I put the sort logic:

 Protected Sub GroupMatchListView_Sorting(sender As Object, e As System.Web.UI.WebControls.ListViewSortEventArgs) Handles GroupMatchListView.Sorting
        ''
        ''Something goes here that sorts the ListView
        ''Maybe something that uses
        ''IComparer
        ''or
        ''GroupMatchListView.Items.OrderBy()
    End Sub

Thanks again.

EDIT: I think I’m on the right track. I take GroupMatchListView.Items, use OrderBy, and assign the results to a List(Of ListViewDatItems). Then I clear the GroupMatchListView.Items, and add the items back from my list of ListViewDataItems. However, when I go back to the page, nothing has changed. If I use just DataBind() I get an empty ListView. If I assign the list of ListViewDataItems as the DataSource, then DataBind, I get an error. Anybody know how I can wrap this up?

Here’s what I’ve worked out:

    Protected Sub GroupMatchListView_Sorting(sender As Object, e As System.Web.UI.WebControls.ListViewSortEventArgs) Handles GroupMatchListView.Sorting

            Dim caesar As List(Of ListViewDataItem) = (GroupMatchListView.Items.OrderBy(Function(i) CType(i.FindControl("FirstName"), Label).Text)).ToList()

            GroupMatchListView.Items.Clear()

            For Each i As ListViewDataItem In caesar
                GroupMatchListView.Items.Add(i)
            Next

            ''I don't know what comes next.  The following does not work:
            ''GroupMatchListView.DataSource = GroupMatchListView.Items
            ''GroupMatchListView.DataBind()
        End Sub

Answer 1

Well, I couldn’t do it with GroupMatchesListView.Items. Instead, I threw the results of my earlier query into a Session variable. Then when it came time to sort, I pulled it out, sorted it, and sent it back to Session.

Here’s the code:

• First I threw it into Session

      goliath = (From f In wholeResults _
                    Group f By f.v_patient Into Group _
                    Order By v_patient.last_name, v_patient.first_name, v_patient.date_of_birth _
                    Select New With {.PatientID = v_patient.patient_id, .LastName = v_patient.last_name, .FirstName = v_patient.first_name, _
                       .DOB = v_patient.date_of_birth, .Ins = v_patient.insname, .MatchCount = Group.Count(), .Matches = Group}).ToList()
  
  Session("ListOfMatches") = goliath
  GroupMatchListView.DataSource = goliath
  

• Then I worked my magic

  Protected Sub GroupMatchListView_Sorting(sender As Object, e As System.Web.UI.WebControls.ListViewSortEventArgs) Handles GroupMatchListView.Sorting

          Dim interimMatches As IEnumerable(Of Object) = CType(Session("ListOfMatches"), IEnumerable(Of Object))
  
          Select Case e.SortExpression
              Case "LastName"
                  If CurrentSortExpression = "LastName" Then
                      interimMatches = interimMatches.Reverse()
                  Else
                      interimMatches = interimMatches.OrderBy(Function(i) CType(i.LastName, String)).ToList()
                      CurrentSortExpression = "LastName"
                  End If
              Case "FirstName"
                  If CurrentSortExpression = "FirstName" Then
                      interimMatches = interimMatches.Reverse()
                  Else
                      interimMatches = interimMatches.OrderBy(Function(i) CType(i.FirstName, String)).ToList()
                      CurrentSortExpression = "FirstName"
                  End If
              Case "DOB"
                  If CurrentSortExpression = "DOB" Then
                      interimMatches = interimMatches.Reverse()
                  Else
                      interimMatches = interimMatches.OrderBy(Function(i) CType(i.DOB, Date)).ToList()
                      CurrentSortExpression = "DOB"
                  End If
              Case "Ins"
                  If CurrentSortExpression = "Ins" Then
                      interimMatches = interimMatches.Reverse()
                  Else
                      interimMatches = interimMatches.OrderBy(Function(i) CType(i.Ins, String)).ToList()
                      CurrentSortExpression = "Ins"
                  End If
          End Select
          Session("ListOfMatches") = interimMatches
          ViewState("CurrentSortExpression") = CurrentSortExpression
          GroupMatchListView.DataSource = interimMatches
          GroupMatchListView.DataBind()
  
      End Sub
  

Hope this helps someone.