Implement filter helpers for ajax table controllers (#9660)

Reduces boiler plate code.

app/Http/Controllers/PaginatedAjaxController.php

@@ -65,7 +65,7 @@ abstract class PaginatedAjaxController extends Controller
     }
 
     /**
-     * Defines search fields will be searched in order
+     * Defines search fields. They will be searched in order.
      *
      * @param \Illuminate\Http\Request $request
      * @return array
@@ -76,6 +76,18 @@ abstract class PaginatedAjaxController extends Controller
         return [];
     }
 
+    /**
+     * Defines filter fields.  Request and table fields must match.
+     *
+     * @param \Illuminate\Http\Request $request
+     * @return array
+     * @SuppressWarnings(PHPMD.UnusedFormalParameter)
+     */
+    protected function filterFields($request)
+    {
+        return [];
+    }
+
     /**
      * Format an item for display.  Default is pass-through
      *
@@ -88,7 +100,7 @@ abstract class PaginatedAjaxController extends Controller
     }
 
     /**
-     * @param string
+     * @param string $search
      * @param Builder $query
      * @param array $fields
      * @return Builder
@@ -107,6 +119,23 @@ abstract class PaginatedAjaxController extends Controller
         return $query;
     }
 
+    /**
+     * @param Request $request
+     * @param Builder $query
+     * @param array $fields
+     */
+    protected function filter($request, $query, $fields)
+    {
+        foreach ($fields as $target => $field) {
+            if ($value = $request->get($field)) {
+                if (is_string($target)) {
+                    $query->where($target, $value);
+                } else {
+                    $query->where($field, $value);
+                }
+            }
+        }
+    }
 
     /**
      * Validate the given request with the given rules.