You can preprocess (filter) the posted field values using custom filters. A recipe script can define its own filter function and add it to the $FoxFilterFunctions array like this:

$FoxFilterFunctions['mycustomfilter'] = 'MyCustomFilterFunction';
function MyCustomFilterFunction($pagename, $fields) {
   ...process any field values here....
   return $fields;

Then a Fox form can call the filter function with parameter foxfilter=mycustomfilter or as a hidden input control of form (:input hidden foxfilter mycustomfilter :)

Fox will use a series of filters in the specified order if several filter function names are given, like


You can find use of foxfilters in Cookbook:FoxForum. Additional examples of filters can be found in Cookbook:Fox-FilterExamples