Last Five Pages Visited Cookie

Question

Hi,

So, I have a series of product pages and all I'd like to do is store the last 5 products viewed in a cookie so it can be displayed as a site-history. The problem I have isn't adding the five initial items to the cookie, its when they view 6, 7 or 10 items. Does anyone have any really decent suggestions on how to tackle this?

Currently I have this flawed logic (i have replaced the cookie name (xxx) for brevity);

Dim i As Integer = 0
        Dim productcount As Integer = 0

        If HttpContext.Current.Request.Cookies("xxx") Is Nothing Then
            Dim gingernuts As New HttpCookie("xxx")
            gingernuts.Values("productcount") = 0
            gingernuts.Expires = DateTime.Now.AddDays(365)
            HttpContext.Current.Response.Cookies.Add(gingernuts)
        End If

        productcount = HttpContext.Current.Request.Cookies("xxx")("productcount")

        For i = 0 To productcount
            If HttpContext.Current.Request.Cookies("xxx")("product" & i & "") = "" Then
                HttpContext.Current.Response.Cookies("xxx")("product" & i & "") = Request.QueryString("id")
            Else
                HttpContext.Current.Response.Cookies("xxx")("product" & i & "") = HttpContext.Current.Request.Cookies("xxx")("product" & i & "")
            End If
        Next

        If productcount = 5 Then
            HttpContext.Current.Response.Cookies("xxx")("productcount") = 5
            HttpContext.Current.Response.Cookies("xxx")("product0") = ""
        Else
            HttpContext.Current.Response.Cookies("xxx")("productcount") = productcount + 1
        End If

Suggestions and critisism welcomed and appreciated.

Chris

Answer 1

This is how i will do it, if I am understanding your question right :)
If product count is less than 5 just append the new product. Else replace product0 with product1 till 4 and then add new product at 4

    If productcount < 5 Then 'Do the null value check before this
        HttpContext.Current.Response.Cookies("xxx")("productcount") = productCount + 1
        HttpContext.Current.Response.Cookies("xxx")("product" & productCount + 1) = ""

    Else
        For i = 0 To productcount - 1
           'Replace product 0 with 1, 1 with 2...till 3 with 4 
            HttpContext.Current.Response.Cookies("xxx")("product" & i & "") = HttpContext.Current.Response.Cookies("xxx")("product" & i + 1& "")

       Next
       HttpContext.Current.Response.Cookies("xxx")("product" & 4 & "") =  Request.QueryString("id")
    End If

Answer 2

Just use a simple cookie value which is a comma delimited list of the most recently viewed product IDs. (Note my VB.NET is that strong).

MostRecentIDs as String() '' // Instance level variables
Const ListSize = 5

'' // in a method somewhere
context As HttpContext = HttpContext.Current
cookie As HttpCookie = context.Request.Cookies("mri")
mri As Queue(Of String)

If cookie Is Nothing Then
    mri = New Queue(Of String)(cookie.Value.Split(",".ToCharArray())
Else
    mri = New Queue(Of String)
    cookie = New HttpCookie("mri")
End If

If mri.Contains(Request.QueryString("id")) Then

    If mri.Count >= ListSize Then mri.Dequeue()

    mri.Enqueue(Request.QueryString("id"))

End If

MostRecentIDs = mri.ToArray();

cookie.Value = String.Join(",", MostRecentIDs)
cookie.Expires = DateTime.Now.AddDays(365)

context.Response.Add(cookie)

• Now you have access to the most recent product IDs as a simple string array.
• This code handles the case where the cookie has not yet been created.
• The cookie itself is much smaller.
• Managing the size of the list can easily be paramaterised.

Code above based on the tested C# code below that I dropped into an empty ASPX file:-

const int listSize = 8;
string[] _mru;

protected void Page_Load(object sender, EventArgs e)
{
 HttpCookie cookie = Request.Cookies["mru"];
 Queue<string> mru;
 if (cookie != null)
 {
  mru = new Queue<string>(cookie.Value.Split(','));
 }
 else
 {
  mru = new Queue<string>();
  cookie = new HttpCookie("mru"); 
 }

 if (!mru.Contains(Request.QueryString["id"]))
 {
  if (mru.Count >= listSize) mru.Dequeue();

  mru.Enqueue(Request.QueryString["id"]);
 }

 _mru = mru.ToArray();

 cookie.Value = String.Join(",", _mru);
 cookie.Expires = DateTime.Now.AddDays(365);

 Response.Cookies.Add(cookie);

}

Answer 3

Anthony answered this question perfectly, but for future reference and for those using VB, this is the code:

    Imports System.Collections.Generic

    Const listSize As Integer = 5
    Private _mru As String()

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim cookie As HttpCookie = Request.Cookies("mru")

        Dim mru As Queue(Of String)
        If cookie IsNot Nothing Then
            mru = New Queue(Of String)(cookie.Value.Split(","c))
        Else
            mru = New Queue(Of String)()
            cookie = New HttpCookie("mru")
        End If

        If mru.Count >= listSize Then
            mru.Dequeue()
        End If

        mru.Enqueue(Request.QueryString("id"))

        _mru = mru.ToArray()

        cookie.Value = [String].Join(",", _mru)
        cookie.Expires = DateTime.Now.AddDays(365)


        Response.Cookies.Add(cookie)
End Sub

Many thanks to all the contributors here also.