- Add support for custom callback functions on filter button click

admin_interface/static/admin_interface/508/dropdown-filter.js

@@ -5,23 +5,32 @@ if (typeof (django) !== 'undefined' && typeof (django.jQuery) !== 'undefined') {
     'use strict';
     $(document).ready(function () {
       const filters = document.querySelectorAll('#changelist-filter .list-filter-dropdown select')
-      let options = ''
+      let query = ''
       // Override the default onchange handler of each filter
       for (const filter of filters) {
         // This needs to be a function expression so `this` references the filter elements themselves
         filter.onchange = function() {
           let value = this.options[this.selectedIndex].value
-          if (options !== '') {
+          if (query !== '') {
           	value = value.replace('?', '&')
 	        }
-          options = options.concat(value)
+          query = query.concat(value)
         };
       }
 
       const applyFiltersButton = document.querySelector('#submit-filters');
       if (applyFiltersButton) {
         applyFiltersButton.onclick = function () {
-          window.location = options
+          // The code below allows the 508 filter button handler to call functions with the name 
+          // `custom_filter_callback` to handle the query string logic for filters defined outside of this repo and the
+          // native Django Admin Console filters.
+          var custom_filter_query = ""
+          if (typeof custom_filter_callback === "function") {
+            custom_filter_query = custom_filter_callback($)
+          }
+          ////////////////
+
+          window.location = query + custom_filter_query
         };
       }
     });