I have a page which contains a user control. The structure of the page is as shown below:
Incase your not able to see the above image, please check it at http://i54.tinypic.com/2r4id5f.jpg Now, apart from the contents of the UserControl, I'd like to cache the entire page. I tried using the OutputCache attribute in the .aspx page, however it caches the contents of the UserControl as well.
Kindly let me know how will I be able to cache the contents of the page except that of the user control.
Thanks in advance.
I think you can use the asp.net Substitution control to achieve this. Here is a link to ScottGu walking through an example.
The basic idea is that you cache you whole page as per usual, but mark parts for substitution that can be replaced for each request.
I think you are looking for VaryByControl. Also check out this post on fragment caching
Look at using substitutions.
This should help
However, the snag is, since substitution is done outside of the Page lifecycle, you can't render a user control for your substitution. You have to write a method that returns a string for the substitution. But this may work for you.
Have you tried adding the #OutputCache to both the usercontrol and the page but the usercontrol set the varyByParam="qsvalue;postvalue" where qsvalue is a generated query string you make random for every call of the page and postvalue is the same for postback.
The user control will still get cached, but in theory it should never get a chache hit as the qsvalue/postvalue is always different from that cached. It may not scale well - best set duration to the minimum as well, to prevent large numbers of them building up in the cache.
Related
Im adding a literal control to my ascx page
<asp:Literal ID="customLiteral" runat="server" />
Inside the Page_Load method I'm populating this text dynamically using the httpContext. I need to read some cookies to set the value of this Literal.
customLiteral.Text = Utility.RenderText(HttpContext.Current) + "<h3>" + DateTime.Now.ToShortTimeString() + "</h3>";
This works perfectly fine on the first load of the page. But does not hit my RenderText method on subsequent loads, so does not honor the value of cookies to render this literal. I added in the date value for testing and the value also remains a constant. Would the literal value be cached somehow? I'm also hitting the breakpoints inside my Page_Load only once on the first load. Is there a better way to achieve what I want here?
Based on your series of interactions with Greg, I suspect that some form of output caching is occurring. If so, there are handful of ways to get whatever data you're trying to have presented in real-time and on each load to show up on page refresh.
The key to implementation comes in the form of something called post-cache substitution (https://learn.microsoft.com/en-us/previous-versions/ms227429(v=vs.140)?redirectedfrom=MSDN) This technique is also known as "donut caching" because when you think about a donut, there's a hole that's cut in the middle. To compare: if your HTML page output were the donut, the "hole" in the middle of it would be the location where you want to place your output (your Literal control) on-demand each time the page is served and not just rendered in the page lifecycle.
Post-cache substitution can be done entirely within code, but I've preferred to use the Substitution control (https://learn.microsoft.com/en-us/dotnet/api/system.web.ui.webcontrols.substitution?view=netframework-4.8) as it makes things a little easier to understand. This control consists of two logically separate parts. There's the section that responds within the normal ASP.NET page/control lifecycle (e.g., Page_Load). The other portion is a public static method that gets called on the control just before the served back to a user from the output cache. That static method is where you might serve up the contents of what you're currently attempting to show with your Literal control.
I present at conferences and events on caching a lot, and I developed a sequence diagram to help my audiences understand what's going on:
I normally work with SharePoint, and I've implemented this in numerous scenarios to great effect. I hope it works for you!
Is there a trusted way to disable the direct access to an special web page? I mean I want to open it only by clicking on a Button for example. I know I can access to the webpage by using this code but It can not prevent accessing to the web page directly (Pasting the url or typing it):
Response.Redirect("~/Code.aspx")
Thanks
This is a long shot because I don't have the time to test this now (I can see some downvotes coming already!), but...
In the "Code.aspx" page, check for Session["allowed"]. If the value is not there, end the response.
Next, make another page (from where Code.aspx can be accessed). In this page, set Session["allowed"] and then do a Server.Transfer() to Code.aspx, which will then run OK.
Finally, at the end of processing Code.aspx., remember to clear the Session["allowed"] variable again.
Hope this makes even vague sense :)
You may be able to write a piece of code on page load that checks the contents of HttpContext.Current.Request.ServerVariables("HTTP_REFERER") - if it's blank, a user has navigated to the page directly and you can handle it that way.
On the source page create a token into a hiddenfield. To your button add PostBackUrl property and let it point to your destination page.
On the destination page you can validate that the request was made from your allowed source page. And you dont need to use session and all its drawback.
Check this Link for detailed information about how to use the mentioned property.
We have a site where all pages are output cached, i.e. the caching is on aspx-level with VaryByParam="*". Now there is a requirement to make a gallup control, i.e. a small "How is this site working for you?" and then when the user clicks an answer the results are shown.
The gallup is implemented as a usercontrol that is added to the master page so gallups can be added to any page to which a gallup is created in the cms. The problem is that output cache naturally caches all clicks so when user no 2 votes he sees the results that where calculated after the first vote on that alternative.
Now I'm trying to use cache substition. I added an asp:Substition tag where the user control used to be, load the control dynamically and render it (using this approach http://coderwall.com/p/4ajzqq). The problem is that the postbacks that voting triggers is never fired. Apparently the method that the substition control executes is loaded outside the page life cycle or too late.
Any ideas?
Regards,
Mathias
I solved this by skipping the substitution control and just used the user control as normal, so the gallup/question view was output cached. Then in the click handler for the answer alternatives I added
Response.Cache.SetNoServerCaching();
which exempted the results view from output cache and hence it was updated as it should.
It is also possible to use Response.Cache.SetNoServerCaching() in Global.asax, using VaryByCustom. It merely requires sensing in Global.asax whether the page is a post-back or not. Here is a code example.
I'm retro-fitting a .aspx page with AJAX functionality (using VB, not C#). The codebehind populates the page with data pulled from a web-service. The page has two panels that are populted (with different data, of course) in this way. On a full page refresh, one or both panels might need to be populated. But populating Panel 2 can take a long time, and I need to be able to update panel 1 without refreshing Panel 2. Hence the need for AJAX (right?)
The solution I've come up with still has the old .aspx page with .aspx.vb codebehind, but introduces a Generic Handler (.ashx) page into the mix. Those first two components do the work on the user's first visit or on a full page refresh, but when AJAX is invoked, the request is handled by the .ashx page.
First question: Is this sound architecture? I haven't found a situation online quite like mine. Originally, I wanted to make the .aspx page into the AJAX handler by having the codebehind implement IHttpRequest, and then providing "ProcessRequest" and "IsReusable" methods, but I found I couldn't separate a regular visit to the page from an AJAX request, so my AJAX handlers took over even on the first visit to the page. Second question: Am I right to think that this approach (making the .aspx page do double-duty as the AJAX handler) will never work? Is it impossible to tell whether we're getting a full-page request or a partial-page (AJAX) request?
If the architecture is good, then I need to dynamically generate a lot of HTML in the .ashx file, right? If that is right, should I send HTML back to the client, or should I encode it in some way? I've heard of JSON encryption, but haven't figured out how to use it yet. So, Third question: Is "context.Response.Write" the only pipeline for sending data back to the client? And, if so, should I send back HTML or some kind of JSON-encoded objects?
Thanks in advance.
It sounds as if the page requires some AJAX functionality added to the UI.
Suggest using an UpdatePanel for each web form element that needs to have AJAXy refresh
functionality. That'll save you from having to refactor a bunch of code, and introduce a whole lot of HTML creation on your .ashx.
It'll be more maintainable over the long run, and require a shorter development cycle.
As pointed out by others, UpdatePanel would be a easier way - but you need to use multiple update panels with UpdateMode property set as conditional. Then you can trigger the update-panel refresh using any button on the page (see AsyncPostBackTrigger) or even using java-script (see this & this). On the server side, you may decide what has triggered the partial post-back and act accordingly by bypassing certain code if not needed.
You can also go with your approach - trick here is to capture the page output using HttpServerUtility.Execute in your ashx and write it back into the response (see this article where this trick has been used to capture user control output). Only limitation with this approach is that you can only simulate GET requests to your page and so you may have to change your page to accept parameters via query string. Personally, I will suggest that you create a user control that accept parameters via method/properties and will generate necessary output and then use the control on your page and in ashx (by dynmaically loading it in a temperory page - see this article).
EDIT: I am using jquery to illustrate how to do it from grid-row-view.
$(document).ready(function() {
$("tr.ajax-grid-row").click(function() {
$("#hidden-field-id").val($(this).find(".row-id").val()); // fill hidden filed
$("#hidden-button-id").click(); // simulate button click
});
});
You can place above script in the head element in markup - it is assuming that you have decorated each grid-row-view with css class "ajax-grid-row" and each row will have hidden field decorated with css class "row-id" to store row identifier or the value that you want to pass to server for that row. You can also use cell (but then you need to use innerHTML to get the value per row). "hidden-field-id" and "hidden-button-id" are client ids for hidden field and submit button - you should use Control.ClientID to get actual control ids if those are server controls.
JSON is not for that purpose, it is to pass objects serialized with a nice light weight notation, is you need to stream dinamically generated html using ashx, response.Write is what you have. You may want to take a look at MVC
Or you could use jquery if it's just html, the simpliest would be the load function, or you can look into Ajax with jquery. Since the ashx can be served as any resource it can be used in the load function.
I agree with #p.campbell and #R0MANARMY here. UpdatePanel could be the easiest approach here.
But then like me, if you don't want to go the UpdatePanel route, I don't see anything wrong with your approach. However, generating the html dynamically (entirely) at the back end is not a route I'll personally prefer (for the maintainence reasons). I'd rather prefer implementing a solution that will keep the design separate from the data.
I thought you couldn't change the QueryString on the server without a redirect.
But this code works* for me:
Request.QueryString edit
I'm so amazed.
So here are my questions regarding this:
Why is Request.QueryString readonly?
Why does this code/hack work*?
How safe is it, if you change to readonly as soon as you are done editing, both regarding bad errors or unexpected behaviour, and regarding maintaining and understanding the code?
Where in the event cycle would it make most sense to do this crazy edit if you are only using PageLoad and OnPageRender?
*More details:
I have a page with items that are grouped into tabs. Each tab is an asp:LinkButton
I want to be able to link directly to a specific tab. I do that with a QueryString parameter 'tab=tabName'. It works. But when I then click a new tab, the querystring is still in the Url, and thus the tab specified in the Querystring gets activated and not the one I clicked.
By using Request.QueryString edit this does not happen. Then my solution 'works'.
Thanks in advance.
Well the QueryString property is readonly because it cannot be changed on a single request. Obviously the browser sends only one request with only one string so only one collection is created. The hack uses reflection (i.e. manipulates the code and the memory) to change stuff that you cannot change normally. This hack breaks the encapsulation and the design of the QueryString property. You should not use it. It makes no sense from design standpoint. Your query DOES NOT change so why change the object that represents it? Only the browser can send new query string so you are basically lying to your own code about what the browser sent.
If you want the tabs to use the URL just use Hyperlinks instead of LinkButton.
From what I remember reading, this is a security standard that all browsers adhere to. It's main purpose is to stop phishing attacks, where someone could have the website www.MyLameWarcraftPhishingSite.com" and when someone hits the page, rewrite the url to look like www.blizzard.com. The only way to get to that url is to actually redirect to it.
mmm, last post was in Feb 11 - hope its ok to post in this.