Added user_agent to the WebProcessor (#1613)

src/Monolog/Processor/WebProcessor.php

@@ -36,11 +36,12 @@ class WebProcessor implements ProcessorInterface
         'http_method' => 'REQUEST_METHOD',
         'server'      => 'SERVER_NAME',
         'referrer'    => 'HTTP_REFERER',
+        'user_agent'  => 'HTTP_USER_AGENT',
     ];
 
     /**
      * @param array<string, mixed>|\ArrayAccess<string, mixed>|null $serverData  Array or object w/ ArrayAccess that provides access to the $_SERVER data
-     * @param array<string, string>|null                            $extraFields Field names and the related key inside $serverData to be added. If not provided it defaults to: url, ip, http_method, server, referrer
+     * @param array<string, string>|array<string>|null              $extraFields Field names and the related key inside $serverData to be added (or just a list of field names to use the default configured $serverData mapping). If not provided it defaults to: [url, ip, http_method, server, referrer] + unique_id if present in server data
      */
     public function __construct($serverData = null, array $extraFields = null)
     {
@@ -52,20 +53,23 @@ class WebProcessor implements ProcessorInterface
             throw new \UnexpectedValueException('$serverData must be an array or object implementing ArrayAccess.');
         }
 
+        $defaultEnabled = ['url', 'ip', 'http_method', 'server', 'referrer'];
         if (isset($this->serverData['UNIQUE_ID'])) {
             $this->extraFields['unique_id'] = 'UNIQUE_ID';
+            $defaultEnabled[] = 'unique_id';
         }
 
-        if (null !== $extraFields) {
-            if (isset($extraFields[0])) {
-                foreach (array_keys($this->extraFields) as $fieldName) {
-                    if (!in_array($fieldName, $extraFields)) {
-                        unset($this->extraFields[$fieldName]);
-                    }
+        if (null === $extraFields) {
+            $extraFields = $defaultEnabled;
+        }
+        if (isset($extraFields[0])) {
+            foreach (array_keys($this->extraFields) as $fieldName) {
+                if (!in_array($fieldName, $extraFields)) {
+                    unset($this->extraFields[$fieldName]);
                 }
-            } else {
-                $this->extraFields = $extraFields;
             }
+        } else {
+            $this->extraFields = $extraFields;
         }
     }