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Question

c# Counter requires 2 button clicks to update

Answer 1

A:

move this code:

tablePanel.Controls.Add(DataSetToTable(DefaultDataSet(rowCount, colC....

To the prerender event to make the table bind to its data after the button click fired.

Roger Alsing 2010-05-10 05:33:13

As you can see above I'm doing a set of checks before that code is executed. I've moved that entire chunk of code to the Page_PreRender event but the tablePanel is then empty on submit_click.The error is:Specified argument was out of the range of valid values.resultsLabel.Text = Server.HtmlEncode(DataSetToStringXML(TableToDataSet((Table)tablePanel.Controls[0])));

Marko 2010-05-10 05:42:29

Any idea why the values aren't there on submit when the controls are created in PreRender, rather than Page_Load?

Marko 2010-05-10 05:53:01

Answer 2

+1 A:

Just as I recommended in this other question, if you'd like some page logic to execute AFTER the buttons' Click event, put that code into the Page_PreRender instead.

You can read more about it here: ASP.NET page life cycle.

EDIT:

After examining your code more closely, I see that you add stuff and create new controls, which is not a good idea in the PreRender event. Instead, put the code into a separate method. In the Page_Load, check if it is a postback and handle the case when it isn't. In the buttons' click evnt, also add a call to that new method. (thus handling the IsPostback == true case)

Venemo 2010-05-10 05:35:37

Yes but then on my submitButton_click event the tablePanel is empty thus throwing an index out of range error.

Marko 2010-05-10 05:45:09

It's a real catch 22. I moved the method that creates my controls right after the rowCount = rowCount + 1; and colCount = colCount + 1; code, but was experiencing the same issue when tried to submit the values.

Marko 2010-05-10 05:51:53

Edited my answer, gave you a new idea.

Venemo 2010-05-10 06:19:59

Sorry I'm not sure I follow. I'm already checking if it's a postback and if it isn't, I'm just setting the default values to 2 and 4. In every other case the page should be recreating the controls with the updated values (rowCount and ColCount respectively). How will putting that in a method help?

Marko 2010-05-10 09:05:25

The key is calling the method from the buttons' Click event.

Venemo 2010-05-10 11:40:03

The problem is that any time I create controls on the Button Click event, they're not available on the subsequent postback (i.e. submit). This is driving me completely nuts.

Marko 2010-05-10 19:48:07

Okay, but does it work after clicking the button?

Venemo 2010-05-10 22:09:06

Yep I CAN create the controls everytime I assign + 1 to the colCount or rowCount. It works like a charm. But then when I click submit, poof! Paste the c#/ASP.NET code into VS, that's the whole working page and see if you can get it to work. I'm starting to grow white hairs. Gah.

Marko 2010-05-10 22:25:46

I've solved the issue but thanks for your effort. I'll give you +1 once my rep goes up.

Marko 2010-05-11 03:31:22

Okay, I'm happy you could solve it. :)

Venemo 2010-05-11 08:14:23

Answer 3

+1 A:

OK I've solved the problem by following instructions in this post.

Here's my final code - feel free to use it if you ever need to create dynamic controls based on a counter.

Also I wouldn't mind feedback on the overall coding style, I always appreciate others' input.

protected void Page_Load(object sender, EventArgs e)
    {
        string xmlValue = ""; //To read a value from a database
        if (xmlValue.Length > 0)
        {
            if (!Page.IsPostBack)
            {
                DataSet ds = XMLToDataSet(xmlValue);
                Table dimensionsTable = DataSetToTable(ds);
                tablePanel.Controls.Add(dimensionsTable);

                DataTable dt = ds.Tables["Dimensions"];
                rowCount = dt.Rows.Count;
                colCount = dt.Columns.Count;
            }
            else
            {
                tablePanel.Controls.Add(DataSetToTable(DefaultDataSet(rowCount, colCount)));
            }
        }
        else
        {
            if (!Page.IsPostBack)
            {
                rowCount = 2;
                colCount = 4;
            }
            else
            {
                if (GetPostBackControl(this.Page).ID == "addRow")
                {
                    rowCount = rowCount + 1;
                }
                else if (GetPostBackControl(this.Page).ID == "addColumn")
                {
                    colCount = colCount + 1;
                }
            }
            tablePanel.Controls.Add(DataSetToTable(DefaultDataSet(rowCount, colCount)));
        }
    }

    protected void submit_Click(object sender, EventArgs e)
    {
        resultsLabel.Text = Server.HtmlEncode(DataSetToStringXML(TableToDataSet((Table)tablePanel.Controls[0])));
    }
    protected void addColumn_Click(object sender, EventArgs e)
    {

    }

    protected void addRow_Click(object sender, EventArgs e)
    {

    }

    public DataSet TableToDataSet(Table table)
    {
        DataSet ds = new DataSet();

        DataTable dt = new DataTable("Dimensions");
        ds.Tables.Add(dt);

        //Add headers
        for (int i = 0; i < table.Rows[0].Cells.Count; i++)
        {
            DataColumn col = new DataColumn();
            TextBox headerTxtBox = (TextBox)table.Rows[0].Cells[i].Controls[0];

            col.ColumnName = headerTxtBox.Text;
            col.Caption = headerTxtBox.Text;
            dt.Columns.Add(col);
        }


        for (int i = 0; i < table.Rows.Count; i++)
        {
            DataRow valueRow = dt.NewRow();
            for (int x = 0; x < table.Rows[i].Cells.Count; x++)
            {
                TextBox valueTextBox = (TextBox)table.Rows[i].Cells[x].Controls[0];
                valueRow[x] = valueTextBox.Text;
            }
            dt.Rows.Add(valueRow);
        }

        return ds;
    }

    public Table DataSetToTable(DataSet ds)
    {
        DataTable dt = ds.Tables["Dimensions"];
        Table newTable = new Table();

        //Add headers
        TableRow headerRow = new TableRow();
        for (int i = 0; i < dt.Columns.Count; i++)
        {
            TableCell headerCell = new TableCell();
            TextBox headerTxtBox = new TextBox();
            headerTxtBox.ID = "HeadersTxtBox" + i.ToString();
            headerTxtBox.Font.Bold = true;
            headerTxtBox.Text = dt.Columns[i].ColumnName;

            headerCell.Controls.Add(headerTxtBox);
            headerRow.Cells.Add(headerCell);
        }
        newTable.Rows.Add(headerRow);

        //Add value rows
        for (int i = 0; i < dt.Rows.Count; i++)
        {
            TableRow valueRow = new TableRow();
            for (int x = 0; x < dt.Columns.Count; x++)
            {
                TableCell valueCell = new TableCell();
                TextBox valueTxtBox = new TextBox();
                valueTxtBox.ID = "ValueTxtBox" + i.ToString() + i + x + x.ToString();
                valueTxtBox.Text = dt.Rows[i][x].ToString();

                valueCell.Controls.Add(valueTxtBox);
                valueRow.Cells.Add(valueCell);
            }
            newTable.Rows.Add(valueRow);
        }

        return newTable;
    }

    public DataSet DefaultDataSet(int rows, int cols)
    {
        DataSet ds = new DataSet();
        DataTable dt = new DataTable("Dimensions");
        ds.Tables.Add(dt);


        DataColumn nameCol = new DataColumn();
        nameCol.Caption = "Name";
        nameCol.ColumnName = "Name";
        nameCol.DataType = System.Type.GetType("System.String");
        dt.Columns.Add(nameCol);

        DataColumn widthCol = new DataColumn();
        widthCol.Caption = "Width";
        widthCol.ColumnName = "Width";
        widthCol.DataType = System.Type.GetType("System.String");
        dt.Columns.Add(widthCol);

        if (cols > 2)
        {
            DataColumn heightCol = new DataColumn();
            heightCol.Caption = "Height";
            heightCol.ColumnName = "Height";
            heightCol.DataType = System.Type.GetType("System.String");
            dt.Columns.Add(heightCol);
        }
        if (cols > 3)
        {
            DataColumn depthCol = new DataColumn();
            depthCol.Caption = "Depth";
            depthCol.ColumnName = "Depth";
            depthCol.DataType = System.Type.GetType("System.String");
            dt.Columns.Add(depthCol);
        }
        if (cols > 4)
        {
            int newColCount = cols - 4;
            for (int i = 0; i < newColCount; i++)
            {
                DataColumn newCol = new DataColumn();
                newCol.Caption = "New " + i.ToString();
                newCol.ColumnName = "New " + i.ToString();
                newCol.DataType = System.Type.GetType("System.String");
                dt.Columns.Add(newCol);
            }
        }

        for (int i = 0; i < rows; i++)
        {
            DataRow newRow = dt.NewRow();
            newRow["Name"] = "Name " + i.ToString();
            newRow["Width"] = "Width " + i.ToString();
            if (cols > 2)
            {
                newRow["Height"] = "Height " + i.ToString();
            }
            if (cols > 3)
            {
                newRow["Depth"] = "Depth " + i.ToString();
            }
            dt.Rows.Add(newRow);
        }
        return ds;
    }

    public DataSet XMLToDataSet(string xml)
    {
        StringReader sr = new StringReader(xml);
        DataSet ds = new DataSet();
        ds.ReadXml(sr);

        return ds;
    }

    public string DataSetToStringXML(DataSet ds)
    {
        XmlDocument _XMLDoc = new XmlDocument();
        _XMLDoc.LoadXml(ds.GetXml());

        StringWriter sw = new StringWriter();
        XmlTextWriter xw = new XmlTextWriter(sw);

        XmlDocument xml = _XMLDoc;
        xml.WriteTo(xw);
        return sw.ToString();
    }

    private int rowCount
    {
        get { return (int)ViewState["rowCount"]; }
        set { ViewState["rowCount"] = value; }
    }
    private int colCount
    {
        get { return (int)ViewState["colCount"]; }
        set { ViewState["colCount"] = value; }
    }
    public static Control GetPostBackControl(Page page)
    {
        Control control = null;

        string ctrlname = page.Request.Params.Get("__EVENTTARGET");
        if (ctrlname != null && ctrlname != string.Empty)
        {
            control = page.FindControl(ctrlname);
        }
        else
        {
            foreach (string ctl in page.Request.Form)
            {
                Control c = page.FindControl(ctl);
                if (c is System.Web.UI.WebControls.Button)
                {
                    control = c;
                    break;
                }
            }
        }
        return control;
    }

Marko 2010-05-10 23:20:21

This GetPostBackControl is a clever idea.

Venemo 2010-05-11 08:19:46

Side note: in this context, the this instance is equal to the this.Page instance. Thus, you could write "if (!IsPostBack)" or "GetPostBackControl(this)". (Your page inherits from the Page class) ;)

Venemo 2010-05-11 08:21:31

Yeah thank god I found it as its solved all my problems! Thanks for your help, I've given you +1 for your effort. Marko

Marko 2010-05-11 20:48:15

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c# Counter requires 2 button clicks to update

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