I'm having some problems in persisting the viewstate on postback for a Control (vb.net)
here's some code i've put in my control[code]...
I'm setting EnableViewState = "true" everywhere i can, but still no result. Do i really need to set those properties here. (ViewStateMode and EnableViewState) If not, where should i handle this and what is the difference between those properties?
I have the following code to try to use viewstate to save a variable for postback. When post back occurs the SrString value is nothing. I have set the ViewState value at the dropdownlist index chane event and set the variable equal ot ViewState("SrString") at page in the if ispostback block.
[Code]...
I have a datagridview in a form that is dynamically bound to a datatable. When the user clicks a button I update certian columns of the current row with code like this:
Dim i As Integer = myDataGridView.CurrentRow.Index
Me.myDataGridView.Item("closed", i).Value = DBNull.Value
I'm working with Visual Basic 2008 Express. My application opens with the Terms screen, a form that asks the user to declare his acceptance of certain terms and conditions or to decline. If he accepts, the app opens the main screen, giving him access to all the app's facilities. If he declines, the app gives him a message and then closes. Whether he chooses to accept or decline, the app puts his decision in My.Settings so that it can be used next time the app is opened. In this way he is presented with the Terms screen on the next opening if he declined on the last run. But if he accepted on the last run, he is presented with the main screen on his next opening.
All works fine when I do a debug run. But when I build and publish the app onto my desktop it opens with the Main screen instead of the Terms screen.
why it works on F5 but not after publishing?
Public
Class frmTerms
Dim Accept As Boolean
[Code].....
I need to very quickly write an exe system on a laptop where when the laptops are connected to the network they read a database table and store the data locally, so staff can use the laptop while they roam.The laptops have quite small capacity and the company would prefer not to use SQL Express or Access.
My question is, can the data initially be downloaded into the exe application via a dataadapter and dataset, and will that dataset the retain the downloaded data, or will I need to ensure the dataset is written to an XML file and then loaded/unloaded each time the laptop application is started while the staff are travelling ?
I am a web developer who now has to change a Windows service. I never worked on a Windows service before. I have a several programs that can run within this service. I want to persist a value of a variable from program to program.
View 1 RepliesI have been searching for quite a while now but i am unable to find the answer to the following. I am storing a key pair in Windows Store, and recently started receiving the "Keyset does not exist" error. Investigating a bit further i found out it could be two things, 1 - The private key is not stored with the persist key set attribute (X509KeyStorageFlags.PersistKeySet) and 2 - access rights to the key. I have tried both 1 and 2 with no success on one machine (in my machine it works apparently). The strange thing is that when i look into MicrosoftCryptoRSAMachineKeys (and S-1-5-18) the key remains there but only for a period of time then it is deleted which means that it is not persisting.
//If decoded then save as RSACryptoServiceProvider
newCert.PrivateKey = DecodePrivateKey(privateKeyFile, pkPassword)
if (newCert.PrivateKey == null)
[Code]....
I have just found out today that since i am doing this through a WCF service, the application pool is deleting the private key when it reaches its idle time limit so i am completely sure that it is the application pool the one disposing of the private key which causes the key to be deleted from the MicrosoftCryptoRSAMachineKeys and S-1-5-18 folders. Today i left a test running where i disabled Idle time shut down from the application pool bu i am still not sure if the private key will stop persisting with a restart or something like that?
Would anybody know how to make the application pool stop deleting my private keys?
I need some general advice about using ListView. The program was originally written in VB2002, but now it's running in VB2008.The results of my program would typically be a ListView of 30 lines by 8 columns. I need to be able to save this data so that it persists after I close the program. There will never be a need to manipulate the data, so I'm looking for something simple. (There will be a need to print it.) I'm presuming that I need to link to a database to save the data. Correct? If so, can I use the one in Microsoft Works (which I already have), or do I need to get Microsoft Access, or is there some other better (simpler?) alternative?
View 7 RepliesI'm looking for a simple, efficient way to get the position of the browser vertical scrollbar and save it into a session variable in an ASP page. What I'm trying to do is when the user changes a page I've the scroll position stored in a session variable so that when the user returns to the page the page will scroll to their last position.Is there a way to do this? I've seen examples of persisting the scroll position on postback but nothing yet doing exactly what I'm trying to do [code]
View 1 RepliesI need to save the controls location and size on the parent form to file. My aim is to be able to simply copy that file to the path where an instance of my program is running and then it automatically applies the previously saved layout of controls. How can I use My.Settings to do that or is there another better option?
View 12 RepliesSorry for the extra long title, Here's what I want to do.I want to give the user the option of using or not using specific features of the program.If I can set a simple yes or no value that wil persist each time the program run and then depending on the variable turn off or on the feature at start
View 14 Repliesdoes anyone knwos what is the point of persist security info? i have always leave it at default (i'm not sure what value it is) but when i pass the application to my friend he seem not to be able to connect to the db. (btw the application calls
View 2 RepliesInstinctively, I would say that this is impossible, as NHibernate needs to know some mapping information on how to persist a given type. Thus, I encountered some situations in which I could use such a feature. For instance, through a named query or something like so. On the other hand, using a named query would require me to make an addition to the configuration file.
Let's suppose we have an application interacting with some underlying datastore. This datastore is configured through the NHibernate configuration file. Then, I wish to have NHibernate load only a subset of an entity properties, from another subsystem to which my application shouldn't need to interact much, so it is not worthy to define classes for this system, as I only need a fraction of this alien system's information, let's say three out of thirty-two data columns. For that matter, if I chose to load only those three columns let's say for performance concerns, I would then use an anonymous type, perform the required action onto this information, then persist it back to the datastore. Now, it wouldn't be of much interest to do so if I only had one entity to get loaded from the datastore, so let's say I have about 75,000 rows to load into my process. I then shall consider this subset option very seriously!
What strategy should you choose in such situation, if you needed to persist these changes to a subset only of this entity's properties?FYI: I am asking because I must write specific rules of usage with NHibernate, such rules that even a beginner developer would even be able to use it without knowing too much about NHibernate, but only following the rules and guidance of the technical documents I have to produce.
Let's say an application needs to persist mostly immutable data. Let's say the application's data files can grow fairly large. How would you implement a simple transaction processing so that changes are either successfully committed or rolled back?
The only requirement is to use built-in .Net libraries. (no databases, no third party libraries)
Here's my current solution. The data file will have three main sections: (1) header, (2) data, (3) index. For now, the header section simply contains an offset to the start of the index section. The data section will store mostly immutable data. The index section will contain serialized objects with enough information to access the data section.
When the application starts, it only needs to deserialize objects from index section. Anything from the data section can be fetched as needed. As the application gets ready to write changes, it makes a temporary copy of the original header and index sections. These would be small relative to the data section. New data would then be appended to the original data section. Once all data has been written, in memory objects would be serialized to the end of the file to become the new index section.
If all this goes without a hitch, the temporary file can be deleted. If something goes wrong, the temporary file can be used to restore the data file to its original state.
Will this work or is there a more elegant approach?
I am making some changes to a fairly old project.It has a DataGrid with an Inherited Class
Public Class CustomDataGridTextBox
Inherits DataGridTextBoxColumn
and a Override Sub Protected Overloads Overrides Sub Paint (.......What it was doing was alternating the Data Grid Line colours New Requirement is to break up some items in the DataGrid By categories So I have added new lines to the data and sorted so they show up ad category headers (Production Stations) And they would like the Category Header to be a different colour and then the alternating line colours to restart.This did not sound too difficult but that has proven a trap Setting the category header is no problem but restarting the alternating colours is Previously the row was determined to be odd or even to set the colour.Now I am intending to use an Integer to define what colour is used but it persists only for that text box.
How can I get it to extend its life so each call can refer to it and update it and set the desired colour?All I need to do is have an integer variable that will hold its value for the next call?
I am new at the ViewState and i am looking to see what values are stored within it. I know how to loop through an array to check for a value but i do not know how to go about doing that for a ViewState("test") property.
Let's say i have added "bob, tom, Jim" to a ViewState called ViewState("test"). I would like to be able to see if "tom" was in the ViewState("test"). If not then add it but if it exists already then skip it.[code]....
I thought I knew how ViewState worked, but I was wrong.I don't understand why the following ASPX page preserves the value typed into the TextBox after clicking on the Button?(ViewState is disabled for both the page and the TextBox.)
[Code]...
I have had a user of my VB.net web app complain he keeps getting an intermittent error message, causing him to crash out of the system.
Stack Trace:
[FormatException: Invalid character in a Base-64 string.]
System.Convert.FromBase64String(Strings) +0
System.web. UI. LosFormatter.Deserialize(String input) +25
[code]...
It appears from the error message that the viewstate keeps becoming corrupt (see screen-dump below), but I don't understand why. He claims it happens every 2-3 minutes, but I've used the system a lot and have never experienced it.I should mention too that he is using the web-app in a very "non-standard" way. To achieve optimum speed he's actually using remote desktop, to connect to our server directly, and running it as localhost. ("Madness!"- yes, I know. I didn't make the decision.) That may not be relevant of course.
Is it possible to make the viewstate false of whole page including all controls at a time.I mean I don't want to set enableviewstate="false" for all controls..In the page directive of the aspx page I have made enableviewstate="false" but still viewstate of all the controls of the is enabled.. And what the EnableViewState="False"actually works within Page directive.
View 3 RepliesI have a VB.Net web site and on my sign up page I am storing the ViewState in Session. I am using the following code to achieve this.[code].....
This has been working fine for months, then I started seeing the occasional 'System.NullReferenceException: Object reference not set to an instance of an object.'. The exception is raised when I try to get the value of the Text Property from the SelectedItem of a DropDownList, the problem being the DropDownList does not contain items after the page has posted back.The problem is only present when using IE (7 or 8 according to my logs, but I have only tested with 8), but not when using FireFox 3.5.Reverting to using the normal ViewState persistence mechanism caused the page to work in IE again.There are no ViewState related exceptions logged, it is like the page just 'thinks' it has no stored ViewState.
I agree that the best way to shorten the ViewState is to disable it on the ASP.Net controls that don't need it. Keeping it small from the beginning is a great habit.I have also heard that it is already compressed (although can be true... there are ways of compressing it even more, has described in this Stack Overflow question).
My question here is not if it should be compressed... is: when should ViewState be compressed?If we have a ViewState of 410 characters it will weight 410 bytes in a page, while a ViewState of 13.843 characters equals 13.5 KB.
13.5KB is a considerable weight already. And if I compress a CSS file that height 10KB, I think it is also worthy compressing a ViewState of 13.5KB, even if that means a little extra "thinking" on the server.
But is 410 bytes of ViewState worth the extra processing on the server?At what point is it worth compressing?
I have a form with its method being "get" that passes the variables and their values to the query string, respectively. However, it also passes the viewstate variable in the query string. Now, I have a very long viewstate value on the given page, and if passed in the query string, the viewstate variable will cause the page to error out, due to "too long of a query string" which happens to also be too long of a url.
I cannot merely remove the viewstate variable - I need it. But I need to pass the viewstate variable along via some method other than get when the form is submitted, while the other inputs of the form (the non-hidden inputs) are appended to the query string.
I have Dim a(15) as integer i wont to save this array in Viewstate .
View 2 RepliesHow do I convert the following ASP code (vb.net) to win form (vb.net)? I get a n error on ViewState.
Protected Sub TextBox_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) _
Handles TextBox1.TextChanged, TextBox2.TextChanged
IsSaveRequired = True
End Sub
Protected Sub SaveButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles SaveButton.Click
If IsSaveRequired Then save required.
End If
End Sub
[Code]...
I have an app where I need to dynamically choose an SQLDataSource for a GridView so I can use 1 of 2 stored procedures, depending on who is logged into the system. My problem is that I am using logic like this, in the button click...
If Session("SiteType") = "Type1" Then
GridView1.DataSourceID = "SqlDataSource2"
Else
[code]....
This happens when you click the button that reveals the panel with the gridview in it. The user then makes changes (basically adjusting a text box on one or more liens of the grid) and then clicks "save". However, the gridview no longer knows its DataSourceID once this happens, so when I try to go through the gridview's rows - there are none.
If, in the save button's click, I put the same code, it (of course) blanks out any of the data changes I made in the form. So, simply put - how do I dynamically choose the SqlDataSource, but only one time, so that the program then keeps that SqlDataSourceID associated with the gridview until the end of the cycle? Is this a ViewState thing? I don't totally understand ViewState...
I keep getting the following error message when I run my vb.net web app:The state information is invalid for this page and might be corrupted.After a good search, I came across this Microsoft page, which describes the problem exactly. The likely cause seems to be "scenario 2":[code]I appear to have prevented this error from happening by using EnableEventValidation="False" in the Page node of the markup as recommended here.
View 2 RepliesI need help making this code work better. Currently, what happens is when it reloads, I loose the third value which is a calculated value . I would like for my page to reload without loosing the values for each property and each instance of the user control on the page.
[Code]...
I am using VS 2008, VB and using a dorpdown listbox in my asp.net webpage. I select a value from the dropdown, click the submit button, when the page comes back from the server, the value in the dropdown is blank (default). The dropdown controls viewstate is enabled.
[Code]...
I have to hide the VIEWSTATE and EVENTVALIDATION hidden fields on my ASP.net page at RUN time.
I managed to remove the EVENTVALIDATION like so.............
<%@ Page enableEventValidation="false" EnableViewState="false" %>
But the VIEWSTATE is still there and I cant get rid of it and I need to. (hard to explain why)
I have a massive viewstate hidden field that is causing my application to be unworkable. I have tried:
EnableViewState="false" on every control
EnableViewState="false" in page directive
Page.EnableViewState = false in Page_Init
[code].....