Question

If I have a page with outputcaching (let’s call it Employees.aspx) which accepts one parameter (through querystring) called Company like this:

 http://www.example.com/Employees.aspx?Company=Google 

How can I avoid duplicate page cache entries for differently cased URLs like:

 http://www.example.com/Employees.aspx?Company=GOOGLE http://www.example.com/Employees.aspx?Company=GOoGlE 

I’ve enabled output caching through the OuputCaching directive as follows:

<%@ OutputCache Duration='300' VaryByParam='Company'  %> 

Is there any way to programatically set what the ‘unique cache key’ for this particular request should be

Answer 1

One hack-esque method of doing it would be to do a VaryByCustom (instead of VaryByParam) and do the .ToLower/.ToUpper in there.

Change the OutputCache directive to something like this:

<%@ OutputCache Duration='300' VaryByCustom='Company' VaryByParam='none' %> 

…and add an override in Global.asax.cs for GetVaryByCustomString:

public override string GetVaryByCustomString(System.Web.HttpContext context, string custom) {     string CustomValue = '';     switch (custom.ToLower())     {         case 'company':             CustomValue = context.Request.QueryString['company'] ?? '';             CustomValue = CustomValue.ToLower();             break;     }     return CustomValue; }