I am a little confused and making it alot more complicated than this needs to be! Here is what I have...
A view which displays a drop down of US States. When the user chooses a state it loads a list of data from a database and returns the results (populates the View Model) and the View renders the information.
What I wanted to do was have have the dropdown trigger an Ajax event which performs the data load, but also wanted it to depreciate if the user didn't have Javascript enabled. How would I go about rendering the view with AND without javascript / ajax?
Hope that makes sense. Thanks for your help.
You can't re-populate a drop-down without jscript. You can do a page-reload with a new drop-down though, although the logic to determine which to use is javascript unfortunately. (Not to mention triggering the re-load of the page on click)
No Javascript support though? That seems kind of out of date, most people run javascript-enabled browsers these days. As for paranoia freaks with javascript turned off, a <noscript> block to tell them to get over it may be appropriate.
To do this with ajax, read this article about cascade dropdowns by Stephen Walther.
To do this without ajax, you could put your first dropdown in a form with a button visible only when javascript is disabled (hide this with javascript for that) wich gets to some action (in another window, maybe) wich returns the second dropdown populated according to the element selected on the first (on the first window, if you have 2 - you could know this url using a viewstate variable).
Related
I thought this would be a trivial feature, but I have lost a fair bit of hair trying to figure it out. I have a jquery mobile web page with a select menu. Users click an item in the drop down list, then later click on a link and navigate to another page. Users then click the back button. The desired result is that the selected item remains selected. Right now, the selection is lost, and it defaults to the first element in the list again.
Things I've tried:
1) Use an asp.net dropdownlist with autopostback. This preserves the selected option, but then I get a page flicker because the entire page is posted back.
2) Wrap above asp.net dropdownlist in an updatepanel. This preserves, doesn't flicker, but it wipes out the jquery mobile styling. Also tried some suggested workarounds with firing a jquery create event, but couldn't get anything working.
3) Write cookies on the select change event in javascript, and read them in the asp page_load event. However, page_load is not called when the back button is clicked, so this had no effect.
4) Tried creating a jquery ajax request to a web page method, but the method must be static and therefore I can't get it to modify the page.
Any other ideas? Is it just me or should this indeed be a problem that's been solved a million times?
As an FYI, I am a newbie at web programming, so please spell it out if you have an answer :) (come from a c++/database background).
Thanks!
Turns out even the date scroller could not survive a back button in some cases. For example if the user navigates to another site, and then uses the back button to come back to my jquery mobile site, all my javascript dom manipulations are lost. The solution is non-trivial. I store everything I need to maintain state of a page using html 5 local storage. On the jqm show page event, I detect if all my global variables have been wiped clean, and if so, reload state from local storage. Works perfectly, but it is quite an implementation task. And of course, if local storage is not supported by underlying browser, it all falls to pieces.
want to have search functionality as on this website
http://www.carwale.com/new/search.aspx#budget=6&budget=8&fuel=2
here whenever the user filters search(checks any checkbox), it updates results accordingly,
that can be understood as an ajax filter.
But at the same time, the query string also reflects for the change,
which helps the user to bookmark the filter search for later reference.
changing it through asp.net/javascript may cause the page to reload..
any hint or suggestions on implementing the same would be really helpful..
This can be done with the help of 3 things together
1) as #Aristos said, checkboxes with Auto Postback enabled
2) Ajax control toolkit Modalpopup, which gets fired automatically on every async postback (http://weblogs.asp.net/ruslan/pages/ajax-update-progress-updateprogress-in-ajax-modal-popup-modalpopupextender.aspx or http://mattberseth.com/blog/2007/07/modalpopup_as_an_ajax_progress.html)
3) History Points (http://msdn.microsoft.com/en-us/library/cc488548.aspx)
This can be done completely without the use of jQuery, if you dont want to use it.
-- For the first part, he have a set of check boxes list with autopostback.
In every post back the list is updated base on the selected check box.
All is simple until now, the cool is that is have a nice interactive interface (made with javascript and jQuery).
-- About the second part, how its change the url so can be bookmark with out reload the page. The trick here is that is place the parameters after the anchor # eg:
/new/search.aspx#budget=2
Using the anchor # the page is not reload and stay as it is. So when some one click on the check boxes, via javascript is also update the url, but only what is after the # so the page stay as is with out fully reload.
Now the parameters after the # can not read on code behind but only via javascript.
So when you have bookmark this page and you go direct to eg /new/search.aspx#budget=2 the javascript reads what is after the # and translate it to commands, check the appropriate checkboxes, and ask for refresh the content. All that can be done only via javascript.
I see that is use the jQuery history plugin as helper with this schema.
http://archive.plugins.jquery.com/project/history
The same trick with parameters after # is done from amazon, when you navigate on catalog, from page to page.
-- One more clever trick that is done is that is open a full page wait, so the user can not interact with the page until the page is ready again. If it not do that, and the user make very fast two clicks on the check boxes, then this can cause a full page post back on updatepanel and this can lose the previous settings.
Is there a straightforward way to use server-side validation with ASP.NET's validation controls in a form that's displayed in a modal dialog? I am using jQuery and SimpleModal (in C#, VS2010, .NET 4.0)
I've got a modal form which works fine. I need to use a server-side validation because the logic depends on data specific to the record being accessed
My solution for the project I'm working on now is to use a jQuery ajax call to pass all the form data to the server and get back the validation results before allowing the post to proceed. But this is relatively time consuming to implement, and in some situations I'm dealing with now all the validation code exists already.
The first challenge is that of course the modal dialog will close on a full postback. So you could put an UpdatePanel inside the dialog... without even thinking about this too much, though, I assumed that it wouldn't work out that well. It doesn't. And the form which opens the modal dialog to begin with is already in an UpdatePanel, which further confuses matters.
Anyway, I tried putting the contents of the modal form in an UpdatePanel for the heck of it. It does actually do a partial postback, the dialog remains open, but the contents of the dialog do not get updated with anything I change server side. If I close and re-open the dialog on the same page after testing the validation code, though, its contents are in fact updated to reflect these changes. Obviously the way the dialog is rendered is confusing ASP.NET. Or vice-versa. But this just seems sketchy from the get-go.
Rather than trying to hack my way through this problem I was hoping that others had some suggestions about a better way to approach this. Or just tell me I'm trying to hard too mix apples and oranges and I should keep it all client side (or client side + jQuery ajax) if that is the only sensible thing to do.
The two approaches I've taken:
1) submit the data via ajax, the response includes a success:true or false. If false, there is a message included that details the issue.
2) submit the form normally. If there is a validation problem, but the errors in a hidden div on the page and write JS to check for content in that div when the page loads and display the warning/error as necessary.
I have an aspx page with a set of controls.
A small JS script written on top of jQuery allows the user to drag "li" elements from one list to another.
What I would like now is for my C# code to be able to figure out which items the user has placed in which list after the page is posted back to the server.
Does anyone know how I can do this?
Thanks.
Without some specifics, its hard to get into details. But for ASP.NET server-side controls, the trick is properly maintaining viewstate (or just bypassing it). So strategically you've got two fundamental options:
1) Track the changes server-side by using AJAX to push updates to the server.
2) Track the data client-side by updating some element ASP.NET could understand. My personal favorite is to use a hidden form field that I add a user's "moves" to in a format that can be replayed in my web form.
The easiest way to do it would be to add a HiddenField to your page. Whenever the lists change, populate the HiddenField's value accordingly. When a postback occurs, the HiddenField's value will be available on the server side.
What i've done in the past with drag & drop functionality in ASP.NET, is read the DOM elements via jQuery, and do an AJAX postback with the values in those DOM elements as a parameter.
I'm writing an asp.net web app. and i've hit a bit of a brick wall.
basically i have 2 pages, the main page with a text box in and a popup that contains a treeview.
My problem is this. when i select a treeview item i want the program to perform some database transactions using asp.net and then pass the value retrieved from the database into a javascript function that passes the data back from the popup page to the parent page. My problem is that i cannot find any way of calling a javascript function from asp.net. I've tried assigning attributes to controls on page load, but this does not work as when the page loads the data has not been retrieved from the database.
Have a look at the ClientScriptManager class. You can register scripts from code-behind that will run when the HTML page loads. Those scripts can call other javascript functions on the page.
There are many tutorials and examples on the Web. Here's one I found that may help but there are many more.
How to use the client script manager
You hit the nail on the head when you said "I've tried assigning attributes to controls on page load, but this does not work as when the page loads the data has not been retrieved from the database." You just need to discover when you're pulling the data from the database, and then assign the values after that. Without looking at your code, there's no way to know for sure, but Page_PreRender is probably a good bet to assign your values...it's probably after you're pulling information from the db...it's pretty much the last place that you can make things happen before the html is generated for the client.
You can invoke a function resided in the Main Page and call that function in the Main Page from the Child Page which is your pop up window.
Please refer to these links for references
http://chiragrdarji.wordpress.com/2007/03/10/call-parent-windows-javascript-function-from-child-window-or-passing-data-from-child-window-to-parent-window-in-javascript/
http://www.webmasterworld.com/forum91/2957.htm
http://hspinfo.wordpress.com/2008/01/12/call-parent-windows-javascript-function-from-child-window/
This one helps with retrieving popups from values using javascript
http://www.eggheadcafe.com/articles/20060117.asp
This one shows how to fire a postback using javascript, and manage it in the codebehind.
http://weblogs.asp.net/mnolton/archive/2003/06/04/8260.aspx
If you put them together, and use Control.ClientID to find the actual "html name" of your asp.net controls, you'll be able to set that up in no time.
Might not be the prettiest way to do it in town, and incidentally make little baby Jesus cry, but anyway, it works.
[edit]Oh. I just saw that it seems I answered the question the other way around, or "how to trigger codebehind from Javascript". I think the method I suggest may help you, if you use it right.
The javascript of the popup should pass the information to the parent window, and the parent window function should call a postback when it receives the information.
The javascript of the popup window should be only registered on a postback with the correct information retrieved, so that when the postback occurs on the popup because of the selection of the right information, the window closes and passes the information to the parent page.
The parent page, triggering postback, does the thingies you need it to, and the app resumes "normally" from there on, doing whatever you need it to, outside of the popup page.