Log File

In this article, we will adopt a simple mechanism to log errors and exceptions in website,

The error will get logged in a text file on the server.

The error file will be created on a daily basis, whenever the error is encountered

Public Shared Sub WriteErrorLog(ByVal errorMessage As String, ByVal errorStack As String, ByVal methodName As String)

Dim path As String = "~/LOG/" & DateTime.Today.ToString("dd-MM-yy") & ".txt"

If (Not File.Exists(System.Web.HttpContext.Current.Server.MapPath(path))) Then

File.Create(System.Web.HttpContext.Current.Server.MapPath(path)).Close()

End If

Using w As StreamWriter = File.AppendText(System.Web.HttpContext.Current.Server.MapPath(path))

w.WriteLine(Constants.vbCrLf & "Log DateTime : " & DateTime.Now.ToString(System.Globalization.CultureInfo.InvariantCulture))

w.WriteLine("Page :- " & System.Web.HttpContext.Current.Request.Url.AbsolutePath.ToString.Trim)

w.WriteLine("Function Name :- " & methodName)

w.WriteLine("Message :- " & errorMessage)

w.WriteLine("Stack Trace :- " & errorStack)

w.WriteLine("__________________________")

w.Flush()

w.Close()

End Using

End Sub

Protected Sub btnTest_Click(ByVal sender As Object, ByVal e As System.EventArgs)

Try

Dim i As Integer = 1

Dim j As Integer = 0

Response.Write(i \ j)

Catch ex As Exception

WriteErrorLog(ex.Message, ex.StackTrace.ToString.Trim, ex.TargetSite.Name)

End Try

End Sub

OutPut

__________________________

Log DateTime : 07/15/2009 15:25:20

Page :- /Default.aspx

Function Name :- btnTest_Click

Message :- Attempted to divide by zero.

Stack Trace :- at Default.aspx.btnTest_Click(Object sender, EventArgs e) in D:\Test\Default.aspx.vb:line 107

__________________________

Same thing you can do in Globa.asax, at Application_Error event. You can get an Server last error by Server.GetLastError()

Sub Application_Error(ByVal sender As Object, ByVal e As EventArgs)

' Code that runs when an unhandled error occurs

Dim objErr As Exception = Server.GetLastError().GetBaseException()

'Function Name not be correct at application level error

WriteErrorLog(objErr .Message, objErr .StackTrace.ToString.Trim, "")

'IF you want you can redirect to user after log into log file here

' Response.Redirect("Error.aspx")

End Sub

Showing Total in GridView

'Declare Variable

Dim Total As Double

Protected Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As GridViewRowEventArgs)

Select Case e.Row.RowType

Case DataControlRowType.DataRow, ListItemType.Item

'Calculate total for the field of each row and alternating row, Cell number change according to your field place

Total += CDbl(e.Row.Cells(0).Text)

Case DataControlRowType.Footer

'Use the footer to display the summary row.

e.Row.Cells(0).Text = Total.ToString("#,###.00")

End Select

End Sub

Calculations in Gridview

1. <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
2. DataKeyNames="ItemID" DataSourceID="sqlDataSource1"
3. onrowdatabound="GridView1_RowDataBound">
4. <Columns>
5. <asp:CommandField ShowDeleteButton="True" ShowEditButton="True" />
6. <asp:BoundField DataField="ItemID" HeaderText="ItemID" InsertVisible="False"
7. ReadOnly="True" SortExpression="ItemID" />
8. <asp:TemplateField HeaderText="quantity" SortExpression="quantity">
9. <EditItemTemplate>
10. <asp:TextBox ID="txtQuantity" runat="server" Text='<%# Bind("quantity") %>'></asp:TextBox>
11. </EditItemTemplate>
12. <ItemTemplate>
13. <asp:Label ID="Label1" runat="server" Text='<%# Bind("quantity") %>'></asp:Label>
14. </ItemTemplate>
15. </asp:TemplateField>
16. <asp:TemplateField HeaderText="price" SortExpression="price">
17. <EditItemTemplate>
18. <asp:TextBox ID="txtPrice" runat="server" Text='<%# Bind("price") %>'></asp:TextBox>
19. </EditItemTemplate>
20. <ItemTemplate>
21. <asp:Label ID="Label2" runat="server" Text='<%# Bind("price") %>'></asp:Label>
22. </ItemTemplate>
23. </asp:TemplateField>
24. <asp:TemplateField HeaderText="amount" SortExpression="amount">
25. <EditItemTemplate>
26. <asp:TextBox ID="txtAmount" runat="server" Text='<%# Bind("amount") %>'></asp:TextBox>
27. </EditItemTemplate>
28. <ItemTemplate>
29. <asp:Label ID="Label3" runat="server" Text='<%# Bind("amount") %>'></asp:Label>
30. </ItemTemplate>
31. </asp:TemplateField>
32. </Columns>
33. </asp:GridView>

and the RowDataBound event is

1. protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
2. {
3. if (e.Row.RowType == DataControlRowType.DataRow)
4. {
5. TextBox txtQuantity = (TextBox)e.Row.FindControl("txtQuantity");
6. TextBox txtPrice = (TextBox)e.Row.FindControl("txtPrice");
7. TextBox txtAmount = (TextBox)e.Row.FindControl("txtAmount");
8. if (txtQuantity != null)
9. {
10. txtQuantity.Attributes.Add("onkeyup", "CalcAmount('" + txtQuantity.ClientID + "','" + txtPrice.ClientID + "','" + txtAmount.ClientID + "')");
11. txtPrice.Attributes.Add("onkeyup", "CalcAmount('" + txtQuantity.ClientID + "','" + txtPrice.ClientID + "','" + txtAmount.ClientID + "')");
12. }
13. }
14. }

and the javascript method will look like this

1. <script type="text/javascript">
2. function CalcAmount(quantity, price, amount) {
3. document.getElementById(amount).value = parseFloat(document.getElementById(quantity).value) * parseFloat(document.getElementById(price).value);
4. }
6. </script>

This way when the values are changed in the quantity and price textboxes,

the corresponding amount textbox updates automatically.

icon on the tab of a website in a web broswer

how to make an icon on the tab of a website in a web broswer

Create an .ico file and add in Header section <link rel="shortcut icon" href="favicon.ico"> You can create an .ico image using this link http://www.chami.com/html-kit/services/favicon/

Getting week of the month from a Date

Getting week of the month from a DateTime variable

// ---- GetWeekOfMonth ---------------------------  //  // Assuming Sunday starts a new week, get the ordinal  // week a date is in...of the date's month  // using Microsoft.VisualBasic;  int GetWeekOfMonth(DateTime Date)  {  long Week;  // get first day of month  DateTime BaseDate = new DateTime(Date.Year, Date.Month, 1);  // get difference, in weeks, between the date and first day of month  Week = DateAndTime.DateDiff(DateInterval.WeekOfYear,   BaseDate,   Date,   Microsoft.VisualBasic.FirstDayOfWeek.Sunday,   FirstWeekOfYear.Jan1);    // want it one, not zero based  return (int)Week + 1;  }  // test it  protected void Button1_Click(object sender, EventArgs e)  {  DateTime Date = new DateTime(2007, 3, 1);  while (Date.Month == 3)  {  int Week = GetWeekOfMonth(Date);  Response.Write(String.Format("{0:d} : {1} <BR>", Date, Week));  Date = Date.AddDays(1);  }  }

RequiredFiledValidator For CheckBoxList

RequiredFiledValidator For CheckBoxList

function checkTemp(sender,args) {      for(var i=0;i<=document.getElementById("CheckBoxList1").firstChild.children.length-1;i++)      {           if(document.getElementById("CheckBoxList1").firstChild.children(i).cells(0).children(0).checked)=='true'           args.IsValid=true           return                          }      args.IsValid=false } <asp:CustomValidator id="valcheckBoxTemp" runat="server" ClientValidationFunction="checkTemp"  ErrorMessage="This is required control "></asp:CustomValidator>

Disable Copy Command

Disable Copy Command

oncopy="return false;" onpaste="return false;" oncut="return false;"

Alternate image when the orginal image is missing

How to provide an alternate image when the orginal image is missing?

<img border=0 src='<%# (Eval("Image").ToString() != null) ? "http://www.mynewsite.com/Images/thumb/" + Eval("Image") : "path_of_dummy_image" %>' />

Finding Particular Controls in Page

Finding Particular Controls in Page

private Control FindNestedControl(Control parent, string controlid)         {             Control c = parent.FindControl(controlid);             if (c != null)                 return c;             else             {                 foreach (Control child in parent.Controls)                 {                     c = FindNestedControl(child, controlid);                     if (c != null)                         return c;                 }             }             return null;         } Eg :- DropDownList ddlMyList = FindNestedControl(this.Page," ddlMyList") as DropDownList;

EncryptString & DecryptString

EncryptString

private string EnryptString (string strEncrypted) {        byte[] b = System.Text.ASCIIEncoding.ASCII.GetBytes(strEncrypted);     string encryptedConnectionString = Convert.ToBase64String(b);     return encryptedConnectionString;    }

 

DecryptString

private string DecryptString (string encrString) {        byte[] b = Convert.FromBase64String(encrString);        string decryptedConnectionString = System.Text.ASCIIEncoding.ASCII.GetString(b);        return decryptedConnectionString;    }