I intend to use Javascript to dynamically create a group of html elements (input boxes, select list, radio button, etc.) each time the user clicks "Add More" button.
I have found the Javascript that does that here:
http://viralpatel.net/blogs/2009/01/dynamic-add-textbox-input-button-radio-element-html-javascript.html
http://forums.asp.net/p/1611284/4118564.aspx
So how do I get the values of these dynamically created HTML elements from code-behind? Is there a JQuery way which is better?
Thank you.
I think you'd may be able to do it with a callback/async postback to your ASP.NET page to update the control tree as you update. Not sure how the ViewState is updated/affected by this.
Otherwise, because your messing with the ViewState, so you'll need to revert to accessing them by the Request.Form object.
Related
I have one dropdownlist (with static listitems). On SelectedIndexChanged event of this dropdownlist, I have three cases to check:
1) If the value is 'A', I need to bind another dropdownlist.
2) If value is 'B', I need to hide above another dropdownlist and instead show nothing in place of that i.e. ulitmately hide that particular div.
3) If values is 'C', I need to hide above div and in place of that, show a textbox.
Now, to prevent Page postback each time a value in dropdownlist is changed, I am using UpdatePanel control here.
I have tried using single updatepanel for both these dropdownlists, two separate udpatePanels for each of them.
With two separate updatePanels, I could succeed in calling the "SelectedIndexChanged" event of that dropdownlist, but once the event is called, the changes done in that code are not reflecting on the page.
i.e. if I hide a div when selected value is 'B', it still shows me, or in either case if it is 'A' and I bind another dropdown, it does not even render.
And, if I reload that page, the pervious changes get reflected. Can anybody please tell me what could be wrong here?
Also, please note that I want be able to postback the page programmatically, because that is the I am trying to prevent.
Also, I would like to notify here that I am using all these things in a WizrdStep of an asp.net wizard control.
Would be greatful for any help.
Thank you in advance.
The issue was not because of update panel or dropdownlist.
The problem was with the way my page was being rendered.
I have used url rewriting for my application and I was trying render this page using my customized form tag instead of built-in Html form tag.
That is why updatepanel was not working normally.
I have got it working now using normal Html Form tag and meanwhile I am trying to workout to handle this updatepanel tag as well with my customized form tag.
If I get it solved, I will submit the solution.
Thanks.
I have a custom server control (composite control having dynamically created dropdown boxes and textboxes). I have enabled AJAX in order to avoid page reload.The server control is used inside the ASP.NET webcontrol having few buttons which controls the visibility of the server control. Now I enter values in the dropdown box and texboxes and click on any other button. After this postback the last entered values are gone! The control is not remembering the values. Can anyone help me? How can I retain the values after post back?
Ensure that the controls are given the exact same ID after each postback. Also you might want to try initialising your dynamic controls (DropDownList and TextBox) during Page_Init if possible.
If your custom server control is create dynamically all the controls, then you need to recreate them on every post, and you need to create them before the Page_Load(), or else the asp.net cant know them to filled with the post data.
To solve this, if you can not create them before the Page_Load(), then you can fill them by your self with the posted data by using the Request.Form[YourCustomControl.UniqueID] for all controls.
You need to re-create on each postback, see This article
I'm working on developing a custom control to select items from a predefined list. This is accomplished via 2 ASP.NET ListBox controls, with a few buttons to trigger the movement of ListItems from one ListBox to the other (lets call these ListBoxes lstSelected and lstDeselected).
This is easy enough to do in ASP.NET or JavaScript independently: I have both working. However, if modifications are made via JavaScript, ASP.NET retains no knowledge of this. Is there any way to register the creation of of options in a select tag without AJAX?
You could also do this with traditional postbacks, it doesn't have to be ajax. The postbacks would be triggered by clicking your buttons which change which items are in which listboxes.
You could have a couple of hidden fields, say hdnHasSelectedChanged and hdnHasDeselectedChanged, and set those fields in your javascript code. Then, when a postback really happens, your code-behind can read those hidden fields to detect if changes occurred.
So i have an ASP.NET GridView control in which each column is a 'BoundField'. I did not create a TemplateField(ItemTemplate/EditItemTemplate), because i was planning on using JQuery to convert the BoundField row to a 'Edit' field by just converting the text in each cell to a textbox or textarea when that row was clicked. This is done all client side.
So far all the client side stuff works great. But I have a 'Save' button on each row of the grid that triggers an eventhandler on the server side. In that server side method, i try to grab values of that current row, but they are all the OLD cell values before I modified the fields/data using jquery/javascript.
When i iterate through each cell of the row, it's the same state as it was when it was rendered.
So what i'm trying to understand is. Why do all of this fancy javascript/jquery stuff when the state of the Grid stays exactly as it was when it was rendered when posting back to the server ?
someone please shed some light on this!!!
Thanks!
The GridView controls uses ViewState to persist its state between postbacks. When you do a postback it loads its previous state from the ViewState. Changes that you do via client-side Javascript are ignored. This is simply how the control works.
If you want to keep using the GridView control with inline editing, the easiest option would be to move to edit mode via a postback.
Another option is to have the fields in each row to begin with, only hidden. Then, you could show them via Javascript. You'll be able to access the values on the server.
Yet another option is not use a postback but an Ajax call, so that the grid is not re-rendered when you click the button. But that means you would have to manually collect the values from the grid via client-side code and pass it to the server.
I have an "action" column in my repeater which shows actions a user can select for an item. The column contains ASP.NET HyperLink or LinkButton controls. Some actions are based on whether a user is in a role, which I determine programatically. I'm struggling with the best way to dynamically generate this column when I populate the repeater. Now I am assigning in-line code to the Visible property of each control, but I feel that is sloppy and not very straight forward. Would I be better served using a PlaceHolder control and populating that at runtime? What kind of methods do other people use for situations such as this?
The "normal" way to apply any sort of dynamic rendering to a Template based control such as the Repeater is to handle the ItemCreated or ItemDataBound events.
In your particular case, you could check appropriate conditions within that event handler and toggle the visibility of the relevant "Action" column.
Also, see this question where Ian Quigley posted a code snippet that should serve as a good example for you. It may also help to read my own answer which shows how to use visibility toggling in inline code.