ASPX 文字控件缓存？

Question

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?

Answer 1

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://docs.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://docs.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 (eg, 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!