How can I prevent URLDownloadToFile from retrieving from the cache ?

Question

I am using URLDownloadToFile to retrieve a file from a website. Subsequent calls return the original file rather than an updated version. I assume it is retrieving a cached version.

Answer 1

Call DeleteUrlCacheEntry with the same URL just prior to calling URLDownloadToFile. You will need to link against Wininet.lib

Answer 2

Could you add a harmless query parameter to the end of your URL?

http://stackoverflow.com/?CacheBuster=1020am

Answer 3

Yes, it is pulling a cached version of the file by default. To avoid the cache file completely, pass an IBindStatusCallback object in the lpfnCB parameter of URLDownloadToFile(). In your implemented IBindStatusCallback::GetBindInfo() method, include the BINDF_GETNEWESTVERSION flag, and optionally also the BINDF_NOWRITECACHE flag, in the value you return via the grfBINDF parameter. If you want the cache file, if present, to be updated instead of skippe, specify the BINDF_RESYNCHRONIZE flag instead.