Re: Methods of a collection class are not always called - C# Discussion Boards

Re: Methods of a collection class are not always called

11-Mar-12 16:52

I have a collection class to hold the children of a control in a DIY user interface. The UI allows to add new controls by calling the Add() method of the collection. Nothing special and breakpoints in Add() are reached as long as the calls come from my own code. Everything is as it should be. Alternatively a view can also be loaded from XAML (using the XamlServices class). If that is done, the view is loaded correctly, but none of the breakpoints in any of the collection's methods are reached. As a result the parent control does not react to layout changes when children are added or removed. Still, XamlServices has successfully loaded the controls and their children, just none of my methods have been used and the layout has not been updated.

According to MSDN, XAML fills the collection with reflection (no real surprise) and looks for the IList interface to do that. I have implemented the complete IList interface and set breakpoints in all of the methods and properties, but they are only reached when the methods are called from my own code. Also, the collection may not be a generic list itself, but may be derived from a generic list. That is why I implemented my collection the following way:

public class ControlList : List<Control>, IList // Component is one of my own classes, not WPF, Silverlight or anything else of the usual!
{
    // Just one of the many IList methods
    public new void Add(cPraeComponent oComponent)
    {
        // Here comes code that is only executed when not using XAML
    }
}

I am convinced that XAML calls the methods of the baseclass (the generic list) instead of mine. My only idea up to now is to wrap the whole collection in a wrapper class which does not inherit from anything and implements IList, but this would be one ugly workaround. Does anybody have a better idea?

Edit: I tried deriving the collection from (forgive me) ArrayList, but that also did not change anything. It really looks like XAML always ends up calling the baseclass and not my methods.

I'm invincible, I can't be vinced

Luc Pattyn11-Mar-12 17:26

Luc Pattyn

11-Mar-12 17:26

CDP1802 wrote:
public new void

Luc Pattyn [My Articles] Nil Volentibus Arduum

Re: Methods of a collection class are not always called

CDP180211-Mar-12 23:34

Re: Methods of a collection class are not always called

11-Mar-12 23:34

I assume you are wondering about the order of the modifiers, not about the 'new' modifier itself. As far as I know the sequence of the modifiers is unimportant. You could write 'public new' or 'new public' without changing anything.

I'm invincible, I can't be vinced

lukeer12-Mar-12 3:11

lukeer

12-Mar-12 3:11

I think he wanted to point out that override could work better than new here.

Ciao,

luker

Re: Methods of a collection class are not always called

Luc Pattyn12-Mar-12 3:26

Luc Pattyn

12-Mar-12 3:26

Wrong assumption. IMO the compiler should generate a message when an interface method gets the new keyword, as it most probably defeats the purpose of the interface.

ControlList c1=new ControlList();
IList c2=c1;
c1.Add(new Control()); // will call your Add()
c2.Add(new Control()); // will call the base Add()

Luc Pattyn [My Articles] Nil Volentibus Arduum

Re: Methods of a collection class are not always called

CDP180212-Mar-12 4:03

Re: Methods of a collection class are not always called

12-Mar-12 4:03

They are not virtual or abstract methods, so 'override' will cause a compiler error. Indeed the compiler will also generate a warning if you don't use 'new'. But very obviously this also leads to the methods of the baseclass being taken as implementation of IList and not the new ones.

I'm invincible, I can't be vinced

Luc Pattyn12-Mar-12 4:23

Luc Pattyn

12-Mar-12 4:23

new is not the solution as my code sample explained; what you want is override, and if the base method isn't virtual, you're in trouble.

Anyway, inheriting/implementing both List and IList looks quite fishy. If you insist on using List, you'll have to use aggregation, not inheritance, and provide each and every method you need yourself.

And then there is ObservableCollection as Pete pointed out.

Smile | :)

Luc Pattyn [My Articles] Nil Volentibus Arduum

Re: Methods of a collection class are not always called

CDP180212-Mar-12 21:21

Re: Methods of a collection class are not always called

12-Mar-12 21:21

Good morning!

Luc Pattyn wrote:
new is not the solution as my code sample explained; what you want
is override, and if the base method isn't virtual, you're in trouble.

Yes, you are right. Everything would be ok if the methods were virtual.

Luc Pattyn wrote:
Anyway, inheriting/implementing both List and IList
looks quite fishy. If you insist on using List, you'll have to use
aggregation, not inheritance, and provide each and every method you need
yourself.

I agree again. It is just that 'aggregating' a single class within another means wrapping one class into the other. That would also not have been very elegant, but it would have set all questions about the implementation of IList straight. ObservableList works fine for now, but I must be careful not to get a similar situation again and then I may yet have to wrap it up.

I'm invincible, I can't be vinced

Pete O'Hanlon11-Mar-12 20:01

Pete O'Hanlon

11-Mar-12 20:01

In order for the Xaml to react, your custom collection must implement INotifyCollectionChanged. Take a look at ObservableCollection to see what this does, ad that is the standard collection class used with Xaml.

*pre-emptive celebratory nipple tassle jiggle* - Sean Ewington

"Mind bleach! Send me mind bleach!" - Nagy Vilmos

My blog | My articles | MoXAML PowerToys | Mole 2010 - debugging made easier - my favourite utility

Re: Methods of a collection class are not always called

CDP180212-Mar-12 0:07

Re: Methods of a collection class are not always called

12-Mar-12 0:07

Thank you very much. I did not know about the ObservableCollection class and it appears to be designed for exactly what I am doing. I'm going to try it out right now.

Edit: A first quick test worked and, as a bonus, ObservableCollection also deals with reentrant changes to the collection. Needless to say that I already had my own mechanism in place to avoid that problem. Now it's time to clean up the code.

I'm invincible, I can't be vinced

modified 12-Mar-12 6:41am.

Pete O'Hanlon12-Mar-12 0:43

Pete O'Hanlon

12-Mar-12 0:43

Not a problem. Glad I could help.

*pre-emptive celebratory nipple tassle jiggle* - Sean Ewington

"Mind bleach! Send me mind bleach!" - Nagy Vilmos

My blog | My articles | MoXAML PowerToys | Mole 2010 - debugging made easier - my favourite utility

Re: Methods of a collection class are not always called

Bernhard Hiller11-Mar-12 21:18

Bernhard Hiller

11-Mar-12 21:18

What about not inheriting from List<Control>? I.e.

public class ControlList : IList<Control>

Then you'll need to have the collection as a memeber variable, and forward calls to it, e.g.

protected List<Control> myList = new List<Control>();
public void Add(cPraeComponent oComponent)
{
    //your code here
    //and do not forget to call the member variable's method
    myList.Add(oComponent);
}

That means writing a lot of code, but I think it's worth to try.

Re: Methods of a collection class are not always called

CDP180212-Mar-12 0:27

Export to Excel - DropDownList

12-Mar-12 0:27

Thanks. That's what I meant with wrapping up the collection class. It would probably have worked, but also have been somewhat ugly and unelegant. I used the advice to derive the collection from ObservableCollection and it now works in both cases.

I'm invincible, I can't be vinced

Andrew Woodward11-Mar-12 10:12

Andrew Woodward

11-Mar-12 10:12

Hi,

I have a gridview that is exported to Excel using C#.
This all works great. The GridView is populated after selecting from a dropdownlist to filter the results.
I would like to add a title to the worksheet so users know what the results refer to. I would like to use the value of the dropdownlist. Is this possible.

My code is

ASP.NET

<%@ Page Title="" Language="C#" MasterPageFile="~/MasterPages/MasterPage.master" AutoEventWireup="true" CodeFile="TeamVolumeSplitQ32011.aspx.cs" Inherits="Printing_Team_Usage_TeamVolumeSplit" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
    <asp:DropDownList ID="DropDownList1" runat="server" DataSourceID="TeamNameSrc" 
        DataTextField="LongName" DataValueField="LedgerID" 
        AppendDataBoundItems="True" AutoPostBack="True">
        <asp:ListItem Value = "">Please Make a Selection</asp:ListItem>
    </asp:DropDownList>
    <asp:SqlDataSource ID="TeamNameSrc" runat="server" 
        ConnectionString="<%$ ConnectionStrings:Docupro_ReportingConnectionString %>" 
        SelectCommand="SELECT [LedgerID], [LongName] FROM [tblLedger]">
    </asp:SqlDataSource>
    <br />
    <br />
    <asp:GridView ID="GridView1" runat="server" AllowPaging="True" 
        AllowSorting="True" AutoGenerateColumns="False" BackColor="White" 
        BorderColor="#DEDFDE" BorderStyle="None" BorderWidth="1px" CellPadding="4" 
        DataSourceID="TeamVolumeSrc" ForeColor="Black" GridLines="Vertical" 
        ShowFooter="True" 
        EmptyDataText="There are no records to display" 
        onrowdatabound="GridView1_RowDataBound">
        <PagerSettings Mode="NextPreviousFirstLast" NextPageText="Next" 
            PreviousPageText="Prev" />
        <RowStyle BackColor="#F7F7DE" />
        <Columns>
            <asp:TemplateField HeaderText="User" SortExpression="User">
                <EditItemTemplate>
                    <asp:Label ID="Label1" runat="server" Text='<%# Eval("User") %>'></asp:Label>
                </EditItemTemplate>
                <FooterTemplate>
                    <asp:Label ID="lblUser" runat="server" Font-Bold="True" Text="Totals"></asp:Label>
                </FooterTemplate>
                <ItemTemplate>
                    <asp:Label ID="Label1" runat="server" Text='<%# Bind("User") %>'></asp:Label>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Colour" SortExpression="Colour">
                <EditItemTemplate>
                    <asp:Label ID="Label2" runat="server" Text='<%# Eval("Colour", "{0:#,0}") %>'></asp:Label>
                </EditItemTemplate>
                <FooterTemplate>
                    <asp:Label ID="lblTotalColour" runat="server" Font-Bold="True" Text="Label"></asp:Label>
                </FooterTemplate>
                <ItemTemplate>
                    <asp:Label ID="Label2" runat="server" Text='<%# Bind("Colour", "{0:#,0}") %>'></asp:Label>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="B&W" SortExpression="B&W">
                <EditItemTemplate>
                    <asp:Label ID="Label3" runat="server" Text='<%# Eval("[B&W]", "{0:#,0}") %>'></asp:Label>
                </EditItemTemplate>
                <FooterTemplate>
                    <asp:Label ID="lblTotalBW" runat="server" Font-Bold="True" Text="Label"></asp:Label>
                </FooterTemplate>
                <ItemTemplate>
                    <asp:Label ID="Label3" runat="server" Text='<%# Bind("[B&W]", "{0:#,0}") %>'></asp:Label>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Total Clicks" SortExpression="Total">
                <EditItemTemplate>
                    <asp:Label ID="Label4" runat="server" Text='<%# Eval("[Total Clicks]", "{0:#,0}") %>'></asp:Label>
                </EditItemTemplate>
                <FooterTemplate>
                    <asp:Label ID="lblTotalClicks" runat="server" Font-Bold="True" Text="Label"></asp:Label>
                </FooterTemplate>
                <ItemTemplate>
                    <asp:Label ID="Label4" runat="server" Text='<%# Bind("[Total Clicks]", "{0:#,0}") %>'></asp:Label>
                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
        <FooterStyle BackColor="#CCCC99" />
        <PagerStyle BackColor="#F7F7DE" ForeColor="Black" HorizontalAlign="Right" />
        <SelectedRowStyle BackColor="#CE5D5A" Font-Bold="True" ForeColor="White" />
        <HeaderStyle BackColor="#6B696B" Font-Bold="True" ForeColor="White" />
        <AlternatingRowStyle BackColor="White" />
    </asp:GridView>
    <asp:SqlDataSource ID="TeamVolumeSrc" runat="server" 
        
        
        ConnectionString="<%$ ConnectionStrings:Docupro_ReportingConnectionString %>" SelectCommand="USE Docupro_Reporting
select
	T5.DisplayName AS 'User',
	0+COALESCE(SUM(CASE
		WHEN T2.LongName LIKE '%Colour%' THEN T1.Quantity
	END),0)AS Colour,
	0+COALESCE(SUM(CASE
		WHEN T2.LongName LIKE '%B&W%' THEN T1.Quantity
	END),0)AS 'B&W',
 SUM(T1.Quantity) AS 'Total Clicks'
FROM tblTransaction T1
JOIN tblItem T2 ON T1.ItemID = T2.ItemID
JOIN tblLedger T3 ON T1.LedgerID = T3.LedgerID
JOIN tblTender T4 ON T1.TenderID = T4.TenderID
JOIN tblCustomer T5 ON T4.CustomerID = T5.CustomerID
WHERE (TransactionDateTime BETWEEN '2011-10-01' AND '2012-01-01')
AND 
(T2.LongName <> 'Scan 2' AND T2.LongName <> 'Scan 1')
AND T3.LedgerID = @LedgerID
GROUP BY
	T5.DisplayName
ORDER BY T5.DisplayName">
<SelectParameters>
    <asp:ControlParameter ControlID="DropDownList1" Name="LedgerID" 
        PropertyName="SelectedValue" Type="Int32" />
                
</SelectParameters>
</asp:SqlDataSource>
</asp:Content>
<asp:Content ID="Content3" ContentPlaceHolderID="ContentPlaceHolder2" Runat="Server">
<asp:Button ID="btnExcelExport" runat="server" Text="Export To Excel" 
        onclick="btnExcelExport_Click" />
<br />Paging Enabled?
<asp:RadioButtonList ID="rbPaging" runat="server">
<asp:ListItem  Text = "Yes" Value = "True" Selected = "True">
</asp:ListItem>
<asp:ListItem  Text = "No" Value = "False"></asp:ListItem>
</asp:RadioButtonList>
<br />
</asp:Content>

Code behind is

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.IO;
using System.Configuration;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Text;
public partial class Printing_Team_Usage_TeamVolumeSplit : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        
    }
    int totalColour = 0;
    int totalBW = 0;
    int totalClicks = 0;
    protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            totalColour += Convert.ToInt32(DataBinder.Eval(e.Row.DataItem, "Colour"));
            totalBW += Convert.ToInt32(DataBinder.Eval(e.Row.DataItem, "B&W"));
            totalClicks += Convert.ToInt32(DataBinder.Eval(e.Row.DataItem, "Total clicks"));
        }
        if (e.Row.RowType == DataControlRowType.Footer)
        {
            Label lblColour = (Label)e.Row.FindControl("lblTotalColour");
            Label lblBW = (Label)e.Row.FindControl("lblTotalBW");
            Label lblClicks = (Label)e.Row.FindControl("lblTotalClicks");
            lblColour.Text = totalColour.ToString("#,#");
            lblBW.Text = totalBW.ToString("#,#");
            lblClicks.Text = totalClicks.ToString("#,#");
        }
    }
    protected void btnExcelExport_Click(object sender, EventArgs e)
    {
        Response.Clear();
        Response.Buffer = true;
        Response.AddHeader("content-disposition",
            "attachment;filename=GridViewExport.xls");
        Response.Charset = "";
        Response.ContentType = "application/vnd.ms-excel";
        StringWriter sw = new StringWriter();
        HtmlTextWriter hw = new HtmlTextWriter(sw);
        PrepareForExport(GridView1);
 //       PrepareForExport(GridView2);
        Table tb = new Table();
        TableRow tr1 = new TableRow();
        TableCell cell1 = new TableCell();
        cell1.Controls.Add(GridView1);
        tr1.Cells.Add(cell1);
  //      TableCell cell3 = new TableCell();
  //      cell3.Controls.Add(GridView2);
        TableCell cell2 = new TableCell();
        cell2.Text = " ";
  //      if (rbPreference.SelectedValue == "2")
  //      {
  //          tr1.Cells.Add(cell2);
  //         tr1.Cells.Add(cell3);
  //          tb.Rows.Add(tr1);
  //      }
  //      else
  //      {
            TableRow tr2 = new TableRow();
            tr2.Cells.Add(cell2);
            TableRow tr3 = new TableRow();
  //          tr3.Cells.Add(cell3);
            tb.Rows.Add(tr1);
            tb.Rows.Add(tr2);
            tb.Rows.Add(tr3);
  //      }
        ClearControls(GridView1);
   //     ClearControls(GridView2);
        tb.RenderControl(hw);
        //style to format numbers to string
        string style = @"<style>.textmode{mso-number-format:\@;}</style>";
        Response.Write(style);
        Response.Output.Write(sw.ToString());
        Response.Flush();
        Response.End();
    }
    protected void PrepareForExport(GridView Gridview)
    {
        Gridview.AllowPaging = Convert.ToBoolean(rbPaging.SelectedItem.Value);
        Gridview.DataBind();
        //Change the Header Row back to white color
        Gridview.HeaderRow.Style.Add("background-color", "#FFFFFF");
        //Apply style to Individual Cells
        for (int k = 0; k < Gridview.HeaderRow.Cells.Count; k++)
        {
            Gridview.HeaderRow.Cells[k].Style.Add("background-color", "green");
        }

        for (int i = 0; i < Gridview.Rows.Count; i++)
        {
            GridViewRow row = Gridview.Rows[i];
            //Change Color back to white
            row.BackColor = System.Drawing.Color.White;
            //Apply text style to each Row
            row.Attributes.Add("class", "number");
            //Apply style to Individual Cells of Alternating Row
            if (i % 2 != 0)
            {
                for (int j = 0; j < Gridview.Rows[i].Cells.Count; j++)
                {
                    row.Cells[j].Style.Add("background-color", "#C2D69B");
                }
            }
        }
    }
    private void ClearControls(Control control)
    {
        for (int i = control.Controls.Count - 1; i >= 0; i--)
        {
            ClearControls(control.Controls[i]);
        }
        if (!(control is TableCell))
        {
            if (control.GetType().GetProperty("SelectedItem") != null)
            {
                LiteralControl literal = new LiteralControl();
                control.Parent.Controls.Add(literal);
                try
                {
                    literal.Text =
                        (string)control.GetType().GetProperty("SelectedItem").
                            GetValue(control, null);
                }
                catch
                { }
                control.Parent.Controls.Remove(control);
            }
            else if (control.GetType().GetProperty("Text") != null)
            {
                LiteralControl literal = new LiteralControl();
                control.Parent.Controls.Add(literal);
                literal.Text =
                    (string)control.GetType().GetProperty("Text").
                        GetValue(control, null);
                control.Parent.Controls.Remove(control);
            }
        }
        return;
    }
    public override void VerifyRenderingInServerForm(Control control)
    {
        //   base.VerifyRenderingInServerForm(control);
    }
    
}

Many thanks

Andy

insert image in datagrid

MemberDotNetting11-Mar-12 9:06

Re: insert image in datagrid

11-Mar-12 9:06

private void btnvalidate_Click(object sender, EventArgs e)
{
string adress;

Validateuradress vadrs = new Validateuradress();
adress = (dgv1.SelectedCells[0].Value.ToString());

if (vadrs.validate(adress))
{

DataGridViewImageColumn img = new DataGridViewImageColumn();
Image image = Image.FromFile(@"Valide.png");I have a problem at this level, never accepts the path of the image

dgv1.Columns.Add(img);
img.HeaderText = "Validate";
img.Name = "img";

}

OriginalGriff11-Mar-12 9:41

OriginalGriff

11-Mar-12 9:41

That is probably because you aren't specifying one.
"Valide.png" does not have any path information, so it will be looked for in the current folder - which is likely to be the one the original EXE was run from, unless it has been changed in the meantime.

I would strongly suggest that you specify the path, at least relative to where the EXE started:

string appPath = Path.GetDirectoryName(Application.ExecutablePath);

If your image file is in a floder below that, add the folder name on, and you should be able to get to your file.

Ideological Purity is no substitute for being able to stick your thumb down a pipe to stop the water

Re: insert image in datagrid

MemberDotNetting12-Mar-12 7:09

12-Mar-12 7:09

thank you , Smile | :)

but I'll use it later because I want to click a submit button hard, I want each line before an image is displayed (valid or not valid)
private void btnvalidate_Click(object sender, EventArgs e)
{
string adress;

Validateuradress vadrs = new Validateuradress();
adress = (dgv1.SelectedCells[0].Value.ToString()); // test with a single line

if (vadrs.validate(adress))
{
Image image = Image.FromFile("Valide.png");
dgv1.Columns.Add(new DataGridViewImageColumn() { HeaderText = "Validate", DataPropertyName = "image" });
dgv1.CellFormatting += new DataGridViewCellFormattingEventHandler(dgv1_CellFormatting);

}

}

private void dgv1_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
{
if (e.ColumnIndex == 1 && e.RowIndex != dgv1.NewRowIndex)
{
e.Value = File.ReadAllBytes(dgv1.Rows[e.RowIndex].Cells[1].Value.ToString()); // exeption file not found
}
}

combobox

MemberDotNetting11-Mar-12 4:42

11-Mar-12 4:42

I have a first form with a datagrid I view with one column there is a list of email addresses, I want to retrieve these values in the combobox the second form when click on the button here is the code, it does not work.

private void btnSend_Click(object sender, EventArgs e)
{
int i;
int j = dgv1.Rows.Count;
List<string> liste= new List<string>();

SendMail s = new SendMail();
s.MdiParent = this;

for (i = 0; i < j; i++)
{
liste[i] = dgv1.Rows[i].Cells[0].Value.ToString();
}

s.remplirCombo(liste);
s.Show();

}

Ravi Bhavnani11-Mar-12 5:12

Ravi Bhavnani

11-Mar-12 5:12

MemberDotNetting wrote:
it does not work.

That's a vague statement. What do you mean by "it does not work"?

Can you post the code for s.remplirCombo()? That's where you seem to populate the combobox.

[edit]
OriginalGriff is absolutely right. You need to first construct your list.
[/edit]

/ravi

My new year resolution: 2048 x 1536
Home | Articles | My .NET bits | Freeware
ravib(at)ravib(dot)com

MemberDotNetting11-Mar-12 5:45

11-Mar-12 5:45

public void remplirCombo(List<string> rw)
{
cmb.Items.Add(rw);
}

OriginalGriff11-Mar-12 6:17

OriginalGriff

11-Mar-12 6:17

That needs to change too: Add is to add a single item. You need AddRange instead.
It may be worth your using Clear on the Items list as well, before you do this (to prevent it adding the values two or more times)

public void remplirCombo(List<string> rw)
   {
   cmb.Items.Clear();
   cmb.Items.AddRange(rw);
   }

Ideological Purity is no substitute for being able to stick your thumb down a pipe to stop the water

MemberDotNetting11-Mar-12 6:29