C# - Event To Save Data In ViewState Before Postback
Oct 14, 2010
I am looking for an event firing before a DropdownList auto-postback to save Listbox items (populated with JS) in the ViewState.I tried the OnSelectedIndexChanged event but it's fired too late.
At my user-control I populate listbox with collection and want save data in viewstatecontrolstate for further autopostback using.
protected void btFind_Click(object sender, EventArgs e) { var accounts = new AccountWrapper[2]; accounts[0] = new AccountWrapper { Id = 1, Name = "1" }; [code]...
ListBox is populated at button click. When I save accounts to ViewState listBox is empty, when not it displays collection good.
i bind a DataTable to a gridview.i want to use the DataTable in some postback event, and ii want to use viewstate. does gridview save data in viewstate? if no what is the best way to do this.
(full story :i have a custom gridview derived from standard asp.net gridview, and i put a button in header to export data to excel, i want to use data saved in viewstate to export to excel)
I need some help in the technical approach with the following scenario:-
1) A dropdownlist with some options. It has a postback action on the selectedIndexChange server side event handler. For example, lets say it contains language options such as english, french etc.
2) Repeater with a label and the textbox control. For example label is Emp Name and textbox is containing the Emp Designation. We have to save emp designation in the various languages.
3) Every time i pick something from the dropdown, i have to flip the textbox control and fill the form. Now i want to save the given data of the texbox in the viewstate. So that every time, the user changes the dropdown selection, he can see the repeater data corresponding to the dropdown selection.
4) I guess some kind of relationship between the dropdown option and the repeater data is needed. But how can we make this thing work.
Now which is the best technique to save the data on the server side? I have to keep it in the viewstate.
I've got a GridView on my page which has some bound controls, one of which is a label (to display total price):
[Code]....
However this value is not being passed to my page. All I see is '£' symbol, no price which makes me think Viewstate["youpay"] is empty? I have enabled viewstate on the Page and Control tags.
I have a button to Save data as well. In this Save routine, I simply look at the value of the ViewState to determine which button the user clicked, because that determines which code I should process. This used to work but is no longer working.
I have changed the look and feel of the grid by modifying the cols, rows in the gridview. I need to save this in the gridview viewsate, so that it load the modified look and feel next time it loads from the viewsate.
My datasource is an ado data table that I have convert to a new data table so that each row in the original table is now a column with 1 row in my new table. I then bind the new datatable and create dynamic template fields with a text box where I bind the values. My problem is, when I try and retrieve the values changed by the user in the rowcommand event, the template columns no longer exists.
Does anyone know how i can retrieve these values? I've read over and over that you have to rebind the grid on each postback when you use dynamic templates, but I'm not sure how to do that and retrieve the values entered in the text boxes on the client side.
I have searched the web for the answer and saw that mostly variables are saved in viewstate on page.prerender event. Then the value of the variable is set back in page load event.However, when I save a variable in viewstate on prerender or load events, how can viewstate store the value of the variable after it is changed dynamically on codebehind?
Let's say, after page is loaded, user clicked a button which changes the value of the variable in its onClick event. Then the postback event raised since the button was clicked. According to me, the new value should have been lost and cannot be saved in the viewstate if the variable is saved in the viewstate only in prerender event. Because on postback the prerender event wont fire and the value cannot be saved.
Shouldn't I save the variable in the viewstate just before the postback event rises?? If so, how can viewstate store the new value of the variable if the viewstate is saved in prerender event?
I am using link button in updatepanel and click on asp:linkbutton it refereshes all page. to stop _dopostback on link button click.or any alternative to use linkbutton.
I have a composite control that has a couple of private fields that reference values in the cache and these private fields are called during the constructor method. Since a string key is used to identify the value in the cache, I must have a way of storing that string key in such a way that it is available at the time the control is instantiated, and I have to be able to reference it on postbacks without it changing.
In addition, this key is generated the first time the control is loaded, but it should not be changed again after that first time.
How can I accomplish this?
I have already tried saving it to viewstate, but that doesn't work because viewstate is not yet available at the time the control is instantiated.
I have tried using a private field and then checking against Page.IsPostback in the constructor and if it isn't postback, I assign a value to the private field, but on subsequent postbacks it looses it's value, and I can't reassign it in the Page.IsPostBack again because it is an autogenerated GUID.
well what i want to find out is how can i figure out if some change occurd in page when postback , i mean when the first state of the page hahe any changes after postback . I thought maybe somehow to compare viewstaes but i can not find out how can i do that.
I have a grid with rows of data, but the page will fail have several postback. I check it with fiddler and find that view state expands 2-3 times after each post back.
The thing I did to trigger the post back is searching and sorting. I am not sure how it happens.
I want to be able to find the old value of a asp.net control (textbox, checkbox etc) without relying on events (e.g. OnTextChange event). Something like "someTextboxControl.OldText" would be perfect! I imagine that it is stored in the viewstate and need to somehow get at it via a custom control.
When I try to save an object reference in a view state it tries to save the object content using serialisation. to save the object reference only to apply to this object instance after postback?
I am designing a site with that requires users to login in to access info. How do I save the user name and password in viewstate or session. so I can use it in other pages later.
I'm having trouble with a simple radio set of two radio buttons (I don't want to use a RadioButtonList [RBL] because RBL doesn't allow child controls, and in my case, if you select one option, I want to enable a textbox next to the button; yes you could hack this with jQuery to move the textbox, but that's dirty!). I would check one, submit the form (either explicitly or through AutoPostBack), and the CheckedChanged event would never fire. When the page was reloaded, both buttons would be unchecked, regardless of their initial state on non-postback load or the state before form submission.