I have an ascx control which works just fine. It is contained in a larger aspx page. I want to put it in the fragment cache, so I added the appropriate CacheOutput directive at the top. However, now the control on the underlying aspx.cs file has the control variable set to null the second time the page has loaded. I found a few places on the web where it said this would happen, but I also didn’t find a solution to accessing the control.
What am I missing?
Also, can I control where it is cached? Can I make it cache in the browser cache rather than at the server?
Question #1: Output caching only stores the HTML result on the server. If you want to interact or run any code in the user control at all, you may not use full output caching. You may want to look into a lower-level caching, perhaps database or object caching, or embed another user control within this one that uses full output caching itself but the outer user control no longer does.
Question #2: “Can I control where it is cached?” If you use output caching, then no. That always means cache on the server. However, there are lots of different levels of caching. You can only cache a full HTTP response at the browser: a single HTML page, a CSS file, etc. If you want to cache only part of a page at the browser, but have the rest of the page dynamic, you would have to do it with some kind of JavaScript. Either HTML5 local storage, or via AJAX that has appropriate caching headers or responds with a 304 Not Modified response.
Side note: The term “fragment cache” is more often referred to “partial caching” in the ASP.Net world.
SO Tips: These are two questions, and should really be asked as two individual questions in the future.
Also, there are many ways to solve your problems here; if you provided more context to what you are doing and the performance problem you are trying to solve, we could offer more specific answers.