State Management :: Datatable/Shoppingcart Isn't Working
Nov 25, 2010
I have copied this shopping cart from the net and incorporated it into my SearchResult.aspx. I understand the code and it seems simple enough but for some reason I am getting an error when trying to run it. Can someone tell me what is wrong below? The generated error stop at the following point: For Each objDR In objDT.Rows. I was thinking that object was not creative during the page load. So I added an
If IsDBNull(objDT) Then
makeCart()
objDT = Session("Cart")
End If
to check if that object exist or not then try to create it. But that didn't work either. :(
This is the error message:
Object reference not set to an instance of an object.
Description:
An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
Source Error:
[Code]....
This is the code to the page. It take the data from a select button on a gridview1. That doesn't seem to be the problem so I didn't added onto here for you guys to see.
An instance of the shopping cart is created like this:
If HttpContext.Current.Session("ASPNETShoppingCart") Is Nothing Then Instance = New ShoppingCart() Instance.Items = New List(Of CartItem) HttpContext.Current.Session("ASPNETShoppingCart") = Instance Else Instance = CType(HttpContext.Current.Session("ASPNETShoppingCart"), ShoppingCart) End If
I am storing Datatable in Session variable in my project. Is it good practise to do so? The datatable has 20 fields and can run into 1000+ records. Will it hamper my application performance?
I'm working in a web application that uses InProc sesssion to store data then we decided to decided to work with out of process session state. But now I tried to Implement that but it is not working
Which one is faster? For a dropdownlist binding it the first time and using ViewSate or Turning of viewstate, keeping the data in a static datatable and binding the dropdownlist each time on a postback
I have 2 cols. StartTime and EndTime. If user's total time is greater then 30 mins then I am locking user. Here, I used Session and I want keep my session for 30 mins. I did almost everything (I think ?) . Change the setting from IIS, Wrote <sessionState timeout="30"> but it is not working... Till 28 - 29 mins it saves the time, but not above..... After that I changed the session's timeout for 9 hours ex: <sessionstate timeout="5400">..... But still not working.... I don't understant what to do?
My Asp.Net app caches some lookup DataTables to avoid hitting DB for seldomly changed data. When the data does change, however, I would like to use the sqlCacheDependency to get SQL Server to send a notification to my application, which should then reload the table into the cache.
In my application, the callback is not being executed, and the cache is not updated when data is changed in SQL Server.
I'm using BlogEngine and i'm changing it a little bit. I tried to show the online visitors number. I added some code in global.asax. My approach is like:
I defined the count of visitors in App start like Application["OnlineVisitors"] = 0
then i increased the count with 1 in the session start and decreased it in session end but it's not working. I downloaded the website to debug in my computer but i never comes to the breakpoint in the session start function. Also sessionstate mode is inprog cookieless= false and timeout = 20
I have a ViewState persistence module that works perfectly on my local machine, but when I move it to our Dev environment, it does not. There are no errors, but the ViewState gets rendered in the page output as if the module did not exist at all.I have checked everything I can think of including the correct code on the server, the SQL connection string where the ViewState is being stored (yes, the code & server has access to the database as we are using the exact same database to store Session state (just different tables) and I can see entries being added for Session state.
As I alluded before, it is almost as if the control adapter in the .browser file is being ignored (or overridden--is that even possible?).Notable differences: my box is Vista w/IIS 7 (yes, I am testing with IIS 7, NOT the VS2010 mini-server). The server is Server 2003 w/IIS 6. Both my boss and I are sure this was working at one point, but as it is "hidden" from normal view we don't know when it stopped.I can provide more details if someone needs, but again the code itself works on my local box and is pretty much from the SDK.
I have added a list to the cache with an expiry date, however the expiry date doesnt work, im not sure how long the cached item lasts but its no more than a day.
I've a Linkbutton control in the master page. And in the content page(Home.aspx) i'm trying to navigate it an aspx page(Apply.aspx) passing a value using querystring. Everything is working fine when i click the apply linkbutton control for the first time i.e i'm able to get the value the querystring and able to use it.
But when i click on the same linkbutton second time, i'm not getting the querystring value?how to persist the querystring value on reloading?
I've been working on this problem for some time without success. We have this website that has been working for many years now and we have been using cookieless sessions since the begining. Now we are integrating with another site to handle payment throught redirection. This provider ask for two adresses for success or failure of a payment so we have something like [URL] and [URL]. For design purpose thoses two pages do not exists and I use an httpModule to route to the proper page. I use httpApplication.Context.RewritePath to send to the proper page but I can never find back the session my user had before redirecting to the payment provider.
If I change the session mecanism to use cookies (cookieless="false" or cookieless="UseUri") with a few other tweaks, everything works fine Does anybody know if this has a chance to work? Is there a way to re-attach to an existing session?
I have developed a website in asp.net 2.0 with backend MS SQL server 2005. After each 2-3 days when i try to login to my admin panel i get a /server application error "datatable must be set prior to using dataview ".When I made a research on this i found the error is in the caching part of the code where i am using a dataset to fill my dropdown lists. But I am using the same code everywhere and on other place i didn't get any error but on a specific page. i usually get error when i try to login to admin. After successful login i redirect the admin to a page adminBazaar.aspx. and the error is always thrown by dis page only.other pages with the same code are working fine and there are no issues.I am using SqlCachingDependency. but can't figure out how to solve the problem.Right now to solve this I have to go to the server stop the website,then stop the application pool and the restart both. We have created a separate application pool for the website.
I have done a web appllication and when run simultaneously from different locations, the one that is started first would use the one that is started late's session variable and datatable contents. This is an exams web app and pageone.aspx results should never be used for pagetwo.aspx's results, because they are not the same questions.
What can I do to prevent this from happening. I am desperate, people are standing by to do exams and time is not on my side.
I want to don't let the page to go back ,for that i am using the code to expire the page after the first time it loads so that when second time the page will load it will not find the such page in cache ,but problem is that my code is not working propely when i am using page.Ispostback, iam inserting my code here[Code]....
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load Try loginRep = BusinessLogic.SR.GetUserName("99999") System.Web.HttpContext.Current.Items.Clear() System.Web.HttpContext.Current.Items.Add("RepId",loginRep)
I don't any errors and when in the run in the immediate window:
? System.Web.HttpContext.Current.items("RepId") in the immediate window on THAT page I get the OBJECT.
Then I have a hyperlink with navigateurl to the next page "~/ActCnt.aspx"
On that page, ActCnt.aspx, when in the code I have:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.LoadIf Not Page.IsPostBack Then Dim loginRep As BusinessLogic.SalesRep = System.Web.HttpContext.Current.Items("RepId")
In the immediate window ? System.Web.HttpContext.Current.Items("RepId") returns a String that is equal to "RepId".
Even if I change it to not be an object, but a string I only get the Name "RepId" of the keypair. I have NEVER gotten the actual value.
In my webconfig file, I am using Forms authentication and I have:
[Code]....
and my default.aspx page is protected as it should. After logging with the proper credentials I am directed to the protected default.aspx page, however when viewing other pages of my website in chrome, and then going back to the default.aspx page something strange happens. From certain pages in my website the default.aspx redirectes me to the login.aspx page, but not from all pages, only certain ones. This behaviour dosenot accour at all in IE Explorer8 where once I am properly validated in my login.aspx page, I can view the default.aspx page from all other pages in my website until I logout from default.aspx page.
