I found a workaround for my specific need, but I thought I'd ask this question anyway.
Say I have a typical data entry web project with a master page -- instead of using the Session variable and using Response.Redirect or Server.Transfer to redirect users who are part of the way through data entry to the next step, I'd rather use cross-page posting.
I tried setting up one of my websites in this manner, with a button like:
<asp:Button ID="next" text="next" runat="server" PostBackUrl="EnterInfo.aspx" />
When I went to test the changes, my <form> tag hadn't changed at all:
<form id="aspnetForm" action="SelectUser.aspx" method="post" name="aspnetForm">
Did I miss any details here, or is cross-page posting simply not intended for use with a master page?
Edit:
The form tag above is the tag as rendered on the client -- not the server-side tag. I've read MSDN articles (like this one) that seem to me to explicitly state that cross page posting actually posts the form to another page.
Perhaps I've misinterpreted this as changing the form's action, but regardless my source form does not post invoke anything anywhere on my target when I click the button I altered -- it merely posts back to the current page.
I don't think using the PostBackUrl attribute will change the action of the form in the markup, as there could be many other controls just doing a normal postback. I imagine that some javascript is used to change the action of the form when this particular button is pressed.
You need to place a declaration on the second page where data come from.
So you have:
PostBackUrl="EnterInfo.aspx"
On EnterInfo.aspx you declare where you can get informations
<%# PreviousPageType VirtualPath="~/SelectedUser.aspx" %>
and you get them by...
if (Page.PreviousPage != null)
{
if(Page.PreviousPage.IsCrossPagePostBack == true)
{
GetTheClass = PreviousPage.MyDataClass;
}
}
The PostBackUrl not change the form url.
Some reference.
ASP.NET how to access public properties?
Cross-page postbacks and back again retaining data from source page
Ps
At first I was thinking that you have just type what you see at render, but if not the case As #Mystere point out you need to run this inside an asp.net form.
First, as Graham says.. PostBackUrl does not change the postback action. Second, you can only use PostBackUrl on an asp.net enabled form, which means the form must have runat="server"
Related
I have an ASP.NET webforms application and a requirement to add a form to a page which will be posted to an external URL, a payment processing provider. The form needs to include specific hidden inputs, one of which is a hashed string representation of the form data.
I understand given limitations of webforms I can't nest a second form within the main <form runat="server" />. However, I don't have the option to locate my form outside of that main form (due to the CMS this site is built into).
I know I can use an ASP.NET Button control with a PostBackUrl attribute which allows the form to post to a specific URL. However, this posts every form element on the page, including __VIEWSTATE, __EVENTTARGET etc.
This is not desired behaviour. I only want to submit specific data. Also, this makes it difficult (impossible?) to generate the hash representation of the form because this would have to include viewstate etc.
I also don't have the option to post the data from the code behind because the client is expected to continue their interaction at the target URL.
Do I have any options here? This must be possible, but an internet search has returned very little.
UPDATE: I'm looking for a solution that doesn't rely on Javascript.
One option would be to utilize ajax. Simply use it to post data you need and you don't even have to redirect or anything. You'd be in control of literally everything (well as long as the user has javascript turned on, of course).
You can use ajax update panel for this .
put asp:scriptManager on page
<asp:scriptManager></asp:scriptManager>
<asp:updatePanel runat="server">
<contentTemplate>
your controls to be submitted to next page
<asp:button><asp:button>
</contentTemplate>
</asp:updatePanel>
and put other controls outside updatePanel.
I'm having trouble figuring out how to do the following:
On every page (or every page I so desire), I'd like to put a common control widget (e.g. think - Search functionality that contains a textbox+button). What's the best way to do this, and who handles the submit button (assuming it is a submit button)?
i.e. what does my ViewUserControl look like? Does it have a form? does it use jQuery onclick""? Does it post to the main View's action method, or can I redirect it to another Controller/Action?
I have tried using RenderAction of a "Search.ascx" which contains a Form, and is handled by my SearchController... but in the SearchController, it then tries to call RedirectToAction... and I get a complaint about RedirectActions not allowed on Child Actions.
I'm a bit lost on what to do next, so suggestions greatly welcome!
Ray
You seem to be on the right track (using ViewUserControl and RenderPartial). But with the information you have provided, it is not easy to see what you other problems are (RenderAction , ...)
It is easy:
Create a UserControl (.ascx) and get a form in there with URL being /search/..., something that you can get back.
In your views, call RenderPartial and provided the view name
Create your controller to receive the post from your search. This is not the same controller as your parent view controller.
The best way to have the HTML elements show up is to put them in a master page, or in a partial that is referenced by your master page. I would have it be it's own form and submit to your SearchController.
Let me know if you want more particulars.
RenderPartial is the way to go here. Your control.ascx will consist of it's form and submit button.
What's the best way to do this
Probably a partial view. An .ascx file.
and who handles the submit button
(assuming it is a submit button)?
The partial view
what does my ViewUserControl look
like? Does it have a form?
Yes, it has a form. It should be as self contained as possible.
does it use jQuery onclick""? Does it
post to the main View's action method,
or can I redirect it to another
Controller/Action?
Well, whatever fits your exact scenario best. It should probably post to whichever action is most appropriate. That is not likely to be the main view's action, since the partial is reused in different parent views.
I have tried using RenderAction of a
"Search.ascx" which contains a Form,
and is handled by my
SearchController... but in the
SearchController, it then tries to
call RedirectToAction... and I get a
complaint about RedirectActions not
allowed on Child Actions.
You'll probably want to render it using RenderPartial in the parent view:
<%: Html.RenderPartial("MyPartialView.ascx") %>
Ok, I figured out what my problem was. The replies above are correct. I have my own Search.ascx user control and SearchController, I also used RenderPartial, but what stumped me was that I forgot to explicitly specify the controller/action... so then I was fiddling around with onclick events and Url.Action on my button instead.
<% using (Html.BeginForm("MySearchAction", "MySearchController")) { %>
Thanks to all who replied.
I want to do something similar to what happens when you click an asp.net button that has a PostBackURL set. I've tried Server.Transfer but the URL doesn't change (which is something I want). Is there a better way to do this, or alternatively is there a way to make Server.Transfer display the correct URL?
Try Response.Redirect
UPDATE:
You can't do a proper postback from codebehind to my knowledge I'm afraid
See:
Cross-Page Posting in ASP.NET Web Pages
How to: Post ASP.NET Web Pages to a Different Page
asp:Button
ID="Button1"
PostBackUrl="~/TargetPage.aspx"
runat="server"
Text="Submit" />
Edit:
You could also construct a HTTP POST in the codebehind and send it to the target page then write the response out to the browser. This won't change the URL in the brower's address bar to the actual page that the data was POSTed to. What you can do depends on what control you have. Is the page that is POSTed to under your control? Do it contain any text/data that is specific to what is POSTed to it? You could do the POST and then redirect/transfer to the target page but that may or may not display the result of the POST correctly.
How to use HttpWebRequest to send POST request to another web server may be of some help if you decide to go this way.
I'm struggling with an issue I just can find a solution for.
First of all, I can't use asp.net AJAX or anything else thant standard asp.net 2.0 as the server admin won't install anything else.
So here is, what I try to do. (For the curious, skip to the bold question below)
My page consists of several parts, each of which gets loaded by jquery.load(url). One of these page parts gets filled with an aspx that contains a form view. As I don't want to have postbacks, I switch to the EditTemplate of the form view by a simple click on a regular html button that submits a parameter indicating the aspx page to switch to edit mode, e.g.
Page_Load(...)
{
if(Request.Params["SwitchEditMode"]) SwitchEditMode();
}
This works perfectly! Now here the part where I'm stuck. The elements in the EditTemplate are based on a select from a database view and bound to the fields by <%# Bind("xx"). Then I have a html button (no asp control) that submits a parameter to the aspx page that tells it to invoke the DataSource update method. In the dataSource_updating method I look for the controls that contain the values I want to save. But these values are always the same, as when I switch to the edit view. No changes I make in the textboxes or dropdowns are preserved.
A long story short, the question how to save the values from EditTemplate back to the database with jquery?
Up to now I tried several approches, that didn't work out.
In the updating() method look for the controls by FindControl and set e.Command.Parameter["xyz"] = foundcontrol.SelectedValue;. The values are always the same as in the beginning.
Set <asp:parameter name="SampleValue" /> and in the EditTemplate <asp:TextBox Value='<%# Bind("SampleValue")#> The values are always null.
Set a hidden input field with the selected value via javascript. This doesn't work as the control within EditTemplate are only visible after the switch into edit mode
So maybe I'm totally wrong with my ideas, heading into a totally wrong direction and this can be accomplished much easier, but up to now I don't know how to achieve this. I could do it without ajax, but for the user experience I'd prefer the version with jquery.
For all that have read this far and not got confused :-), thanks for your effort!
Best regards,
Andreas
I would forget using a form view and just use a regular html form with regular input controls. Return an object from your web service that has all of your values and populate the controls with ajax and then subjmit with ajax. Either do fully asp.net or fully html/jquery with asmx back end. Otherwise it's just too confusing.
If you load both "modes" of the FormView into the same page using AJAX, you're probably getting duplicate field names. One of them contains the unchanged values which are being saved. How will ASP.NET know the difference? You only want to submit the ones from the EditTemplate, which will require a separate form (or some other hack).
Or perhaps your HTML submit button isn't giving ASP.NET what it needs to repopulate the controls. Are you using ViewState in the page with the FormView?
All in all, this sounds like a hairy combination of technologies... as you well know.
Here's the situation: I have a label's text set, immediately followed by a response.redirect() call as follows (this is just an example, but I believe it describes my situation accurately):
aspx:
<asp:Label runat="server" Text="default text" />
Code-behind (code called on an onclick event):
Label.Text = "foo";
Response.Redirect("Default.aspx");
When the page renders, the label says "default text". What do I need to do differently? My understanding was that such changes would be done automatically behind the scenes, but apparently, not in this case. Thanks.
For a little extra background, the code-behind snippet is called inside a method that's invoked upon an onclick event. There is more to it, but I only included that which is of interest to this issue.
A Response.Redirect call will ask the user's browser to load the page specified in the URL you give it. Because this is a new request for your page the page utilises the text which is contained in your markup (as I assume that the label text is being set inside a button handler or similar).
If you remove the Response.Redirect call your page should work as advertised.
After a redirect you will loose any state information associated to your controls. If you simply want the page to refresh, remove the redirect. After the code has finished executing, the page will refresh and any state will be kept.
Behind the scenes, this works because ASP.NET writes the state information to a hidden input field on the page. When you click a button, the form is posted and ASP.NET deciphers the viewstate. Your code runs, modifying the state, and after that the state is again written to the hidden field and the cycle continues, until you change the page without a POST. This can happen when clicking an hyperlink to another page, or via Response.Redirect(), which instructs the browser to follow the specified url.
ASP and ASP.Net are inherently stateless unless state is explicitly specified. Normally between PostBacks information like the value of a label is contained in the viewstate, but if you change pages that viewstate is lost because it is was being stored in a hidden field on the page.
If you want to maintain the value of the label between calls you need to use one of the state mechanisms (e.g. Session, Preferences) or communication systems (Request (GET, POST)).
Additionally you may be looking for Server.Transfer which will change who is processing the page behind the scenes. Response.Redirect is designed to ditch your current context in most cases.
To persist state, use Server.Transfer instead of Response.Redirect.
So, if I may answer my own question (according to the FAQ, that's encouraged), the short answer is, you don't persist view state through redirects. View state is for postbacks, not redirects.
Bonus: Everything you ever wanted to know about View State in ASP.NET, with pictures!
For what it's worth (and hopefully it's worth something), Chapter 6 of Pro ASP.NET 3.5 in C# 2008, Second Edition is a terrific resource on the subject. The whole book has been great so far.