CODEWITHSUNDEEP
asp.netgridviewdevexpressaspxgridview
Carlos Mendieta
Carlos Mendieta

Reputation: 872

Why am I losing a DataItemTemplate control in a column when I remove all other columns in an ASPxGridView?

I have a 1 column grid. During user interaction, more columns are built and added dynamically. No matter how many columns are added or removed from the grid, the initial Print button column should always remain. Here's the grid.

                <dx:ASPxGridView ID="gvAdvancedResults"
                    ClientInstanceName="gvAdvancedResults" runat="server" EnableRowsCache="False" KeyFieldName="ID" AutoGenerateColumns="True">
                    <Columns>
                        <dx:GridViewDataColumn Width="3%" VisibleIndex="0" Caption="Print">
                            <DataItemTemplate>
                                <dx:ASPxButton ID="btnDisplayMEC" runat="server" OnClick="btnDisplayMEC_OnClick" ClientInstanceName="btnDisplayMEC" CommandArgument='<%# Eval("ID") %>'
                                    CssClass="reportbutt" BackColor="Transparent" Border-BorderStyle="None" Width="16" Height="16">
                                    <Image Url="~/Assets/Images/printer.png" Width="16" Height="16"></Image>
                                </dx:ASPxButton>
                            </DataItemTemplate>
                        </dx:GridViewDataColumn>
                    </Columns>                                               
                </dx:ASPxGridView>

On a button click, I use the following to clear and repopulate the grid columns from datatable dt

    'Remove all columns except the first (index 0)
    For gix As Integer = gvAdvancedResults.Columns.Count - 1 To 1 Step -1
        If gix <> 0 Then gvAdvancedResults.Columns.RemoveAt(gix)
    Next

    'Add new columns to the gridview
    For Each col As DataColumn In dt.Columns
        Dim xcol As Object = gvAdvancedResults.Columns(col.ColumnName)
        If xcol IsNot Nothing Then Continue For
        Dim newcol As New GridViewDataColumn(col.ColumnName, col.ColumnName)
        gvAdvancedResults.Columns.Add(newcol)
    Next

    gvAdvancedResults.DataSource = dt
    gvAdvancedResults.DataBind()

Now here's the problem. The "Print" column remains through the column removal process (as it should), but the ASPxButton inside the column's DataItemTemplate disappears. All the columns that are supposed to be added, are added.

Why am I losing my print button but keeping its column?

Upvotes: 1

Views: 1107

Answers (2)

Soenhay
Soenhay

Reputation: 4048

To answer your original question, it is probably due to having AutoGenerateColumns set to True. When you bind a dataSource it probably auto generates the columns at that point. You can test this by removing your code that adds the columns and I bet you will still see the columns that were in the dataSource. It might be as simple as setting AutoGenerateColumns to False.

For a few alternative ways of doing this if that doesn't work...

It would be a bit of work but you could try making the button column template in the code behind so that you can just clear and recreate all of the columns during each page load.

Or an easier method would be to use a custom command column like so...

This is c# code but it should be similar in VB:

gvAdvancedResults.Columns.Clear();

GridViewCommandColumn commandCol = new GridViewCommandColumn(" ");//Blank for no caption.
commandCol.Name = "command";
commandCol.Width = Unit.Pixel(30);
commandCol.ButtonType = GridViewCommandButtonType.Image;
gvAdvancedResults.Columns.Add(commandCol);
commandCol.VisibleIndex = 0;

GridViewCommandColumnCustomButton btnPrint = new GridViewCommandColumnCustomButton();
btnPrint.ID = "print";
btnPrint.Image.Url = "~/Assets/Images/printer.png";
btnPrint.Image.ToolTip = "Print";
commandCol.CustomButtons.Add(btnPrint );

//Then add the rest of the columns.

Then add a clientSide CustomButtonClick event to the gridView to handle the actual printing via the CustomCallback event:

<dx:ASPxGridView ID="gvAdvancedResults"
 ClientInstanceName="gvAdvancedResults" runat="server" 
 EnableRowsCache="False" 
 KeyFieldName="ID" 
 AutoGenerateColumns="False"
 OnCustomCallback="gvAdvancedResults_CustomCallback"
     OR
 OnCustomButtonClick="gvAdvancedResults_CustomButtonClick" 
 >
    <ClientSideEvents CustomButtonClick="function(s, e) {
        if (e.buttonID == 'print')  
        {   
           //Trigger a callbackPanel that is the parent to the gridView.
           someCallbackPanel.PerformCallback(gvAdvancedResults.GetRowKey(e.visibleIndex)); 
           //Or trigger a callback on the gridView and use GetRowKey on the server side.
           gvAdvancedResults.PerformCallback('print');//Handle it on the server.
           //Or some other way.
        }
    }" />

Or handle the server side ASPxClientGridView.CustomButtonClick Event. No example unless you really need it.

Notice that I changed AutoGenerateColumns to false since you are manually creating the columns.

Upvotes: 1

Antoine Pelletier
Antoine Pelletier

Reputation: 3316

Maybe if you make two gridviews, one that contain only the button column, and the other one for the rest of the data, that would surely solve the problem as you won't touch the first gridview and only bind your datas to the second gridview. Just a workaround... Not really an easy solution because you already coded the rest.

Upvotes: 0

Related Questions