Journal Entry, November 6th to November 13th 2020

Laravel

1. Mon Nov 9

   • To introduce a blocklist to filter out apiLog records, we first filter by application_id and then 1 or more arrays of values.
   • This lets us do thing like filter multiple statuses, methods, or uris.
   • Ideally we could take it a step further and filter by only status 422 or DELETE methods but the 1 or more aspect makes things seemingly more difficult.
   • Initially my brain halted using nested conditionals in a "if value is present then check the other fields" repeated.
   • The null coalescing operator is doing this for us by either returning null when nothing is found or the result of the in_array check if present.
   • Because something like null ?? false ?? true returns true, it feels almost hackish but I suspect works for any field we throw at it.

   • My first attempt was to have an array of application_id but this made the Collection->where() usage more difficult.

     {
         "blocklist": [
             {
                 "application_id": ["SAGESYNC", "SAGESYNCMS"],
                 "status": ["422"]
             },
             {
                 "application_id": ["SAGESYNCXC4"]
             }
         ]
     }

   • Ultimately we had to settle on this form as the where() clause looks for values.

     {
         "blocklist": [
             {
                 "application_id": "SAGESYNC",
                 "status": ["422"]
             },
             {
                 "application_id": "SAGESYNCMS",
                 "status": ["422"]
             },
             {
                 "application_id": "SAGESYNCXC4"
             }
         ]
     }

     /**
      * Filter columns against configured blocklist.
      *
      * @param string|null $application_id
      * @param string|null $method
      * @param string|null $uri
      * @param string|null $status
      * @return void
      */
     public function isBlocked($application_id, $method, $uri, $status)
     {
         $result = false;
         $blocklist = collect($this->getBlocklist());
         $blocked = $blocklist->where('application_id', $application_id);
         $blocked->each(function ($block) use (&$result, $method, $uri, $status) {
             $methods = Arr::get($block, 'method', null);
             $uris = Arr::get($block, 'uri', null);
             $statuses = Arr::get($block, 'status', null);
             $filtered = $this->hasValue($methods, $method) ?? $this->hasValue($uris, $uri) ?? $this->hasValue($statuses, $status);
             if (is_null($filtered) || $filtered === true) {
                 // $filtered is true when a value is found or null when all fields are null.
                 $result = true;
             }
         });
     
         return $result;
     }
     
     /**
      * An array has value (has normally checks for keys not values).
      *
      * @param array|null $array
      * @param mixed $value
      * @return boolean
      */
     private function hasValue($array, $value)
     {
         if (is_null($array)) {
             return null;
         }
     
         return in_array($value, $array);
     }
     
     /**
      * Retrieve blocklist section from config file.
      *
      * @return null|array
      */
     private function getBlocklist()
     {
         $localDisk = \Storage::disk('local');
         $contents = $localDisk->get("data/apiLogs/config.json");
         $json = json_decode($contents, true);
     
         if (!is_null($json)) {
             return $json['blocklist'];
         }
     
         return null;
     }