Using BreadCrumbs in ASP.Net.

The BreadCrumb is used to maintain the list or keep trail of the pages that one has visited along the way to the present page.
As the breadcrumb is used in the entire project ,so use it as a usercontrol.
Following steps are needed to create a BreadCrumb:-
1)Create a usercontrol and paste the following code in the .ascx.vb page:-
' This class represents a usercontrol helps to implement a breadcrump system
' Usage : Ad the user control to the page where bread crumb system to be implemented
' Add this page tro the DefaultLinks property if it not exiss there
Imports System.Text
Imports System.Collections
Imports System.Collections.Specialized
Public Class BreadCrumb
Inherits System.Web.UI.UserControl

#Region " Web Form Designer Generated Code "

'This call is required by the Web Form Designer.
Private Sub InitializeComponent()

End Sub
Protected WithEvents lblTrail As System.Web.UI.WebControls.Label

'NOTE: The following placeholder declaration is required by the Web Form Designer.
'Do not delete or move it.
Private designerPlaceholderDeclaration As System.Object

Private Sub Page_Init(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Init
'CODEGEN: This method call is required by the Web Form Designer
'Do not modify it using the code editor.
InitializeComponent()
End Sub

#End Region

'Variable holding the Link name of the page
Private _tailName As String
'Variable holding the level of the page
Private _level As Short
'The pagecrumb object of the current page
Private _pageCrumb As New BreadCrumb
'We will use a sorted list as we can use the level as key
Private _crumbList As SortedList

'Each page has a level. The page should declare its level
Public Property Level() As Short
' TO DO : We can check for some constraints here
Get
Return _level
End Get
Set(ByVal Value As Short)
_level = Value
End Set
End Property

Public Structure BreadCrumb

Private _level As Short
Private _url As String
Private _linkName As String

'//We are setting all the properties at the time of construction

Public Sub New(ByVal level As Short, ByVal url As String, ByVal linkName As String)

_level = level
_url = url
_linkName = linkName
End Sub

'//We are making all the properties as read-only.
'//We are not expecting it to change once it is set.
Public ReadOnly Property Level() As Short
Get
Return _level
End Get
End Property

Public ReadOnly Property Url() As String
Get
Return _url
End Get
End Property

Public ReadOnly Property LinkName() As String
Get
Return _linkName
End Get
End Property
End Structure


'Each page needs a meaningful name of it. Let them declare it
Public Property TailName() As String
' TO DO : We can check for some constraints here
Get
Return _tailName
End Get
Set(ByVal Value As String)
_tailName = Value
End Set
End Property

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'We are not disabling viewstate
If Not (Page.IsPostBack) Then

'Minimum level is 1
If (_level <= 0) Then
_level = 1
End If

'If no friendly name gives Untitled as default
If (_tailName = "") Then
_tailName = "Untitled"
End If

'Create a Crumb object based on the properties of this page
_pageCrumb = New BreadCrumb(_level, Request.RawUrl, _tailName)

'Check our Crumb is there in the session...if not create and add it...else get it
If Session.Item("HASH_OF_CRUMPS") Is Nothing Then
_crumbList = New SortedList
Session.Add("HASH_OF_CRUMPS", _crumbList)
Else
_crumbList = Session.Item("HASH_OF_CRUMPS")
End If

'Now modify the List of the breadcrumb
ModifyList()
' Put the breadcrumb from the session of sortlist
PutBreadCrumbs()
End If


End Sub

Private Sub ModifyList()
'Remove all Entries from the list which is higher or equal in level
'Because at a level there can be max 1 entry in the list
RemoveLowerLevelCrumbs()
'If level is 1 set the Crumb as home
If _pageCrumb.Level = 1 Then
_crumbList.Clear()
_crumbList.Add(CType(1, Short), New BreadCrumb(1, "/Home.aspx", "Home"))

Else
'If nothing in the list adds the home link first
If _crumbList.Count = 0 Then
_crumbList.Add(CType(1, Short), New BreadCrumb(1, "/Home.aspx", "Home"))
End If
'Now add the present list also no other check is required here as we have cleaned up the
'List at the start of the function
_crumbList.Add(_level, _pageCrumb)
End If
End Sub

'Function will remove all the entries from the list which is higher or equal to the
'present level
Private Sub RemoveLowerLevelCrumbs()

Dim level As Short
Dim removalList As New ArrayList(_crumbList.Count)
For Each level In _crumbList.Keys
If (level >= _level) Then
removalList.Add(level)
End If
Next
'Now remove all keys in the list
For Each level In removalList
_crumbList.Remove(level)
Next
End Sub


Private Sub PutBreadCrumbs()
Dim linkString As New StringBuilder

Dim pageCrumb As New BreadCrumb
Dim index As Integer

For index = 0 To _crumbList.Count - 2
pageCrumb = _crumbList.GetByIndex(index)
linkString.Append(String.Format("{1} ", pageCrumb.Url, pageCrumb.LinkName))
linkString.Append(" > ")
Next index
'Add the tail also
pageCrumb = _crumbList.GetByIndex(index)
linkString.Append(pageCrumb.LinkName)

lblTrail.Text = linkString.ToString()

End Sub
End Class

Now add a label which will display the pages .
So the html part of the usercontrol for the label is:-


Now use the following in the aspx pages which needs the BreadCrumb:-


The level and the tailname changes according to the page that is to be displayed.
So better prepare a sitemap first.

Hope this article will provide a help to you.

Happy Coding,
Sumit Daripa