<div>
do you use static variables somehow in your code?
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<div>
sorry I new to this. where do you mean? anyware in my code or just in the cart section?
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Is the information only in a session-level variable? &nbsp;Are you sure you're not storing it in an application-level variable? &nbsp;Are you storing something in a database and retrieving it?
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Hi Eval, no not even in the entire stie. Why would this have caused a problem? do you have any other ideas?
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can you post the codes that adds and gets from the cart?
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Did you develop the cart yourself, or is it something you bought? &nbsp;<br />
<br />
Is it a class that gets instantiated? &nbsp;If so, does it exist as a singleton implementation? &nbsp;That is, does it exist as something that belongs to the session instance?
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<div>
Hi below is the code<br />
<br />
Imports Microsoft.VisualBasic<br />
<br />
' The ShoppingCart class<br />
' Holds the items that are in the cart and provides methods for their manipulation<br />
Public Class ShoppingCart<br />
<br />
#Region &quot;Properties&quot;<br />
<br />
&nbsp; &nbsp; Private _items As List(Of CartItem)<br />
&nbsp; &nbsp; Public Property Items() As List(Of CartItem)<br />
&nbsp; &nbsp; &nbsp; &nbsp; Get<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Return _items<br />
&nbsp; &nbsp; &nbsp; &nbsp; End Get<br />
&nbsp; &nbsp; &nbsp; &nbsp; Private Set(ByVal value As List(Of CartItem))<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; _items = value<br />
&nbsp; &nbsp; &nbsp; &nbsp; End Set<br />
&nbsp; &nbsp; End Property<br />
<br />
#End Region<br />
<br />
#Region &quot;Singleton Implementation&quot;<br />
<br />
&nbsp; &nbsp; ' Readonly variables can only be set in initialization or in a constructor<br />
&nbsp; &nbsp; Public Shared ReadOnly Instance As ShoppingCart<br />
&nbsp; &nbsp; ' The static constructor is called as soon as the class is loaded into memory<br />
&nbsp; &nbsp; Shared Sub New()<br />
&nbsp; &nbsp; &nbsp; &nbsp; ' If the cart is not in the session, create one and put it there<br />
&nbsp; &nbsp; &nbsp; &nbsp; ' Otherwise, get it from the session<br />
&nbsp; &nbsp; &nbsp; &nbsp; If HttpContext.Current.Sessio<wbr />n(&quot;ASPNETS<wbr />hoppingCar<wbr />t&quot;) Is Nothing Then<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Instance = New ShoppingCart()<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Instance.Items = New List(Of CartItem)<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; HttpContext.Current.Sessio<wbr />n(&quot;ASPNETS<wbr />hoppingCar<wbr />t&quot;) = Instance<br />
&nbsp; &nbsp; &nbsp; &nbsp; Else<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Instance = CType(HttpContext.Current.<wbr />Session(&quot;A<wbr />SPNETShopp<wbr />ingCart&quot;),<wbr /> ShoppingCart)<br />
&nbsp; &nbsp; &nbsp; &nbsp; End If<br />
<br />
&nbsp; &nbsp; End Sub<br />
<br />
&nbsp; &nbsp; ' A protected constructor ensures that an object can't be created from outside<br />
&nbsp; &nbsp; Protected Sub New()<br />
<br />
&nbsp; &nbsp; End Sub<br />
<br />
#End Region<br />
<br />
#Region &quot;Item Modification Methods&quot;<br />
<br />
&nbsp; &nbsp; ' AddItem() - Adds an item to the shopping<br />
&nbsp; &nbsp; Public Sub AddItem(ByVal NewItem As CartItem)<br />
&nbsp; &nbsp; &nbsp; &nbsp; ' Create a new item to add to the cart<br />
&nbsp; &nbsp; &nbsp; &nbsp; 'Dim newItem = New CartItem(productRef)<br />
&nbsp; &nbsp; &nbsp; &nbsp; 'newItem.ProductRef = &quot;P5&quot;<br />
&nbsp; &nbsp; &nbsp; &nbsp; 'newItem.Description = &quot;ghjghjg&quot;<br />
&nbsp; &nbsp; &nbsp; &nbsp; 'newItem.Quantity = 100<br />
&nbsp; &nbsp; &nbsp; &nbsp; 'newItem.UnitPrice = 0.745<br />
&nbsp; &nbsp; &nbsp; &nbsp; 'newItem.ItemWeight = 0.5<br />
<br />
&nbsp; &nbsp; &nbsp; &nbsp; ' If this item already exists in our list of items, increase the quantity<br />
&nbsp; &nbsp; &nbsp; &nbsp; ' Otherwise, add the new item to the list<br />
&nbsp; &nbsp; &nbsp; &nbsp; If Items.Contains(newItem) Then<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; For Each item As CartItem In Items<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; If item.Equals(newItem) Then<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; item.Quantity += 1<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Return<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; End If<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Next<br />
&nbsp; &nbsp; &nbsp; &nbsp; Else<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 'newItem.Quantity = 1<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Items.Add(newItem)<br />
&nbsp; &nbsp; &nbsp; &nbsp; End If<br />
<br />
&nbsp; &nbsp; End Sub<br />
<br />
&nbsp; &nbsp; ' SetItemQuantity() - Changes the quantity of an item in the cart<br />
&nbsp; &nbsp; Public Sub SetItemQuantity(ByVal productRef As String, ByVal quantity As Integer)<br />
&nbsp; &nbsp; &nbsp; &nbsp; ' If we are setting the quantity to 0, remove the item entirely<br />
&nbsp; &nbsp; &nbsp; &nbsp; If quantity = 0 Then<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; RemoveItem(productRef)<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Return<br />
&nbsp; &nbsp; &nbsp; &nbsp; End If<br />
<br />
&nbsp; &nbsp; &nbsp; &nbsp; ' Find the item and update the quantity<br />
&nbsp; &nbsp; &nbsp; &nbsp; Dim updatedItem = New CartItem(productRef)<br />
&nbsp; &nbsp; &nbsp; &nbsp; For Each item As CartItem In Items<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 'If item.Equals(updatedItem) Then<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; If item.ProductRef.Equals(pro<wbr />ductRef) Then<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; item.Quantity = quantity<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Return<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; End If<br />
&nbsp; &nbsp; &nbsp; &nbsp; Next<br />
&nbsp; &nbsp; End Sub<br />
<br />
&nbsp; &nbsp; ' RemoveItem() - Removes an item from the shopping cart<br />
&nbsp; &nbsp; Public Sub RemoveItem(ByVal productRef As String)<br />
&nbsp; &nbsp; &nbsp; &nbsp; Dim removedItem = New CartItem(productRef)<br />
<br />
&nbsp; &nbsp; &nbsp; &nbsp; For Each item As CartItem In Items<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; If item.ProductRef.Equals(pro<wbr />ductRef) Then<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 'If item.Equals(removedItem) Then<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Items.Remove(item)<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Return<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; End If<br />
&nbsp; &nbsp; &nbsp; &nbsp; Next<br />
&nbsp; &nbsp; End Sub<br />
<br />
#End Region<br />
<br />
#Region &quot;Reporting Methods&quot;<br />
<br />
&nbsp; &nbsp; ' GetSubTotal() - returns the total price of all of the items before tax, shipping, etc.<br />
&nbsp; &nbsp; Public Function GetSubTotal() As Decimal<br />
&nbsp; &nbsp; &nbsp; &nbsp; Dim subTotal As Decimal = 0<br />
&nbsp; &nbsp; &nbsp; &nbsp; For Each item As CartItem In Items<br />
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; subTotal += item.TotalPrice<br />
&nbsp; &nbsp; &nbsp; &nbsp; Next<br />
<br />
&nbsp; &nbsp; &nbsp; &nbsp; Return subTotal<br />
&nbsp; &nbsp; End Function<br />
<br />
#End Region<br />
<br />
End Class<br />
<br />

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<div>
What session state mode are you using?
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Hi Codecruiser, how do I find out that?
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Paul, you are a star. Thank you so much. As you have used this cart before do you think it is the best way of using a shopping cart? <br />
I have just read that some people have problems on web farm where they loose the session every 60mins.
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&gt;Private Shared _Instance As New ShoppingCart<br />
<br />
I dont think that is the way to do it for singletons.
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It's a solid piece of code and it works really well. &nbsp;As I said, I've modified mine extensively and not broken it (permanently!) yet, so it must be pretty resilient!<br />
<br />
My sessions time out after 20 minutes - the default. &nbsp;I'm okay with that, but that may be a problem for other folks. &nbsp;I'm not using the cart in a farm, per se, but in a set of servers that are managed using load balancing. &nbsp;
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CodeCruiser, why do you think its not a good way. It worked fine?
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<div>
Thanks &nbsp;Paul<br />
Ok just opened a new thread if anyone can help<br />
<a href="https://www.experts-exchange.com/questions/27388677/ASP-NET-How-you-use-access-a-vaule-used-on-the-main-form-from-within-a-user-control.html" rel="ugc">https://www.experts-exchange.com/questions/27388677/ASP-NET-How-you-use-access-a-vaule-used-on-the-main-form-from-within-a-user-control.html</a>
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<div>
&gt;CodeCruiser, why do you think its not a good way. It worked fine?<br />
<br />
In singleton, object is instantiated only if it has not been instantiated yet. In the code, you are instantiating it anyway.
</div>


<div>
@CodeCruiser - No, the code looks to see if it exists in the session an creates it only if it doesn't.
</div>


<div>
&gt;No, the code looks to see if it exists in the session an creates it only if it doesn't.<br />
<br />
You changed <br />
<br />
Private Shared _Instance As ShoppingCart<br />
<br />
to<br />
<br />
Private Shared _Instance As <b>New</b> ShoppingCart<br />
<br />
so it creates an instance regardless.
</div>


<div>
But if its working, I guess it does not matter.
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Yes, it creates a new instance in each session (if an instance doesn't exist yet). &nbsp;FWIW, I don't claim to understand it, I just make it work!
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<div>
<div class="content wysiwyg-content">
Hi I am new to asp.net but I have a session varible that stors the items in the cart. I though it was all going well until I tried it on another computer and seen all the items I had added on the fiirst computer were in the cart on the second. <br />
<br />
So to sum iit up the Asp.net session varible is showing to all uesrs<br />
I dont know if this is a coading error or becuase its on a web farm thing.<br />
Please help me.
</div>
</div>


Hi I am new to asp.net but I have a session varible that stors the items in the cart. I though it was all going well until I tried it on another computer and seen all the items I had added on the fiirst computer were in the cart on the second. 

So to sum iit up the Asp.net session varible is showing to all uesrs
I dont know if this is a coading error or becuase its on a web farm thing.
Please help me.

Asp.net session varible is showing to all uesrs

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ASP.NET

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