VS 2008 - Saving And Loading Datatable From A Session Variable?
Mar 25, 2011
I need to save data in a datatable on a web page where the user is adding items to order. I know how to create a datatable and add data to it. And I will be binding it to a gridview control. But I do not want to loose the data when the page does a postback. Do I need to save it to a session variable for this? Or will the data stay in the datatable?
I found this code posted online. Is this how I would save it to a session variable and then load it anytime?
Code:
Dim dt As New DataTable()
Session("MyDataTable") = dt
' To retrieve it from session
Dim dt As DataTable = DirectCast(Session("MyDataTable"), DataTable)
I've got a DataTable that I'm appling to a session variable on inital page_load.
I need to check whether that Session Variable when the page is returned to - ie Not isPostback.
I can do If Session("var") = Nothing Then, but the problem with that is, if the Session variable already has the DataTable applied to it, it will throw back an error stating that Operator '=' is not defined for type 'DataTable' and 'Nothing'.
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?
Consider my dataTable contains 10,000 rows and i want to know the pitfall of storing datatable in a session variable... I want to use it until a new row has been added...What type of session mode should i use?
I am working on a web application that is consuming a Dataset returned by a web service. As the application is running I store that Dataset as a session variable to be used over and over again as the user navigates to the different pages that will edit the tables within the dataset. The idea was the user will only have to wait for the data once when the application loads then the application would use the session variable until the user saves the changes they made, when that happens it would pass the edited tables to the service to update the database. Is there problems with this design and the storage of the Dataset and Datatables as a session variable?
Currently in an .aspx file, I am storing a value (filename that was created in that session) in an hidden text box. When the user clicks on the "Print" labeled Hyperlink control, it opens the file that was stored in the hidden text box control. But when the user goes to different screen (in the same session), I loose the filename value that is stored in the hidden text box control. So I would like to store the filename variable in a session variable. So that if the user leaves this .aspx file and comes back to this .aspx file I can load the value into the hidden text box from the session variable.
I have a web application which uses a session variable to store the logged in userid. If no user is logged in, of course this variable will be empty and the contents displayed on my website are meant for guests. If there is a user logged in, the user specific controls/access/links will then be a displayed.
I am now having issues with my hosting where on shared application pool, the worker recycle is triggered every 90 minutes, this will clear sessions causing all my users to be logged out. I opted for a dedicated application pool, which got worse because I am only allocated 50MB memory limit and if this is reached, the worker recycle is triggered and I lose my sessions again. I have tried as much as possible optimization techniques, e.g. dispose where possible, close connections, disable viewstate for static controls etc but my memory per instance keeps building up from page to page without any signs of improvement. I don't use loops nor store huge objects like bitmaps etc but my sessions are now gone even faster than 90 minutes in shared application pool before.
I have considered using SQL Session State but there isn't a simple guide on using this with MySQL. I am getting desperate and considering using a public variable, a string as a replacement to store logged in user id instead of in a session variable. I am pretty sure this will solve my issue with sessions being recycled but are there any negative consequences of doing this? One problem I can think of is if the user closes the browser, the system will never know that the user is now logged out and this public variable should be nothing. In this scenario, will the GC eventually clear this abandoned public variable.
I have a DataTable for which i do not know how many rows are there in it.. How to get the rows/columns one by one and save it in the desired SQL Table?
What would be the proper syntax in ASP.NEt 3.5 C# to assign a TextBox value to a temporary or session variable to be manipulated (added, subtracted, multiplied, divided) at different points in the application? I want to add a decimal number to this variable in almost every instance as well.
i need to save a timestamp byte[] array between page post backs in asp.net webforms and thought having a global variable in a class would work, but it does not?
I have a publice variable to be used in the same webpage. when the user click on button 1, it does some process and assign a value to my public variable. After that, the user can click on button 2 which needs the public variable value to function. However I see the value of the public variable is 0 when I click on button 2.
On my MVC2 web application I have a form that a user can enter dates, times, comments etc for appointments with clients. We then give him the oppertunity to download it as a vCalendar file. So far, on my controller I have the following code (I have just included the string that stored my vCard data) :
[Code]....
I have worked with uploading and downloading binary files within MVC, but working with stuff like this I am totally lost. This code needs to be saved as a .vcs from withing the client's browser. My return value looks something like this :
I have the dataset. in this i am having total 20 tables with huge amount of data..I want use this data over all the page..so where i can keep this data..
before i used viewstate but the viewstate data is render to page every postback ..so this time the page size is increasing(interanlly viewstate is rendered to page)..so performence wise it was very slow..
Now i change my logic insted of viewstate to i used Globel Dataset on Page Level.. now the performence wise better than viewstate..
i used Like shared dsControls as Dataset at top of the page..so every time i use this dataset..
my quesation is session is better or Globel variable is better way use in my situavation..
I added the following code to global.asax to load up several session variable when a session starts. I'm assuming that when a page goes to use the variable that I should be
1) checking at the page level that the value is valid not 0 when its not expected to be 0, not a zero-length string when its expected to have a length
2) have code at the page level that sets the values if the values have not been set as when the Session timeout, ideally putting the code in a class derived from Page and then deriving all of my pages from the new class so that the code does not have to be repeated in every page
I have some code in my page load event where I just want to fire once when the user opens the Browser. The only issue is if you open a new tab with the same website the session variable does not reset. Is there a way to reset the session variable when you open a new tab or do you have to take the whole web browser down for it to clear the session variable.
I have been spending a better part of a week trying to track down why I am not able to clear all session variables in a web app (vs 2010, vb.net). What I have tracked it down to is that when I remove or abandon sessions that my html pages or codebehind access, it works, but for some reason in any of my class files where I use "Public Shared strConnection as String = HttpContext.Current.Session("strConnection").ToString" to access a session variable, it finds the old one and not the current one. I have to wait for it to time out, go in again, and it will find the new one.
I do not use Linq, and there is only one place in the whole web app that I place the connection string in a variable whcih is when a person logs in. It points them to the correct database. The sqlconnection is set for all of my listviews in Page_Init to make sure that they aren't using any session variable that they create on their own. Interestingly enough that if I use debug to go in each time, exit debug, enter debug again trying to access a different database, it works correct each time. I assume that debug is correctly killing the session variable for the classes for me.
I have some cascading dropdownlists using the ajax toolkit I have a set up datatables in an xsd file. Then use these in a webservice to populate all the fields ... this all works great but now i need to pass an additional paramter to the first dropdownlist ( a date) but don't know how to do this? The method is below...
[Code]....
The other code is:
[Code]....
The first change would be to the tableadapter to add a param to the code i.e
AuditWebDS.TeamsDataTable teams = teamsAdapter.GetTeams(calldate);
but how do i get the calldate param to the webservice method... i tried a session variable but it comes up with session is null ? Is there another better way?
I am performing my first steps with ASP.NET for my employment.Yesterday I tried to perform saving a value to a sessionstate variable, but it does not work.I am using C# and want to code in .NET 3.5. [Code]....
The click performs a postback to a second website where the value is to be displayed on a simple label.The value I initialized in the Global.asax is saved to the variable and then read on the second page, but I cannot manipulate it using the textbox and the button on the first page. I just don't get it...I even tried on different machines and different VS editions.
I am new to asp.net Can you please guide me what is session and session variables ? Please I don't need a comparision of asp session and asp.net session because I don't know anything about asp. I have saw many articles on types of session as well. But still I cant understand exectly what is session and what are session variables in asp.net ?
If I have a DataTable (in-memory) read by my C# program from a flat file, and I want to create it as a new table in a SQL Server database... what is the simplest way to do that?
It seems like something like SqlBulkCopy with an option to create a new destination SQL server table would be on my line of thinking, but I dont see a way.
I am trying to load data from an existing DataTable into a new DataTable. Not sure how to get it started. Do not want to merely copy data, I need to load it in row by row.
protected DataTable GalleryByCat() { // GLinks is the new DataTable I want to construct and bind to a DataList, Repeater, ListView
When using the DataTable.Load(SQLDataReader) method, if the datatable is a property of a class, the set method is not called to populate the object. For example...
MySQLDataReader = command.ExecuteReader(); if (MySQLDataReader.HasRows)
myObjDataTable.Load(MySQLDataReader); -- The result of this will be 0 rows returned. The "Set" method of the object is never called.
