Expose more about job using metadata

README.md

@@ -122,6 +122,17 @@ return array(
   )
 );
  ```
+
+### Getting slm/queue-doctrine specific data
+
+The `DoctrineQueue` will populate all jobs with some additional metadata about the job. This metadata is stored under
+a specific key name. 
+
+```php
+$job->getMetadata(DoctrineQueue::METADATA_SCHEDULED_KEY); // Returns `\DateTimeImmutable` date for which job is scheduled.
+$job->getMetadata(DoctrineQueue::METADATA_PRIORITY_KEY); // Returns integer priority of the job.
+$job->getMetadata(DoctrineQueue::METADATA_ID_KEY); // Returns integer ID of the job in the database.
+```  
 
 Provided Worker Strategies
 --------------------------

src/Queue/DoctrineQueue.php

@@ -31,6 +31,15 @@ class DoctrineQueue extends AbstractQueue implements DoctrineQueueInterface
 
     public const DEFAULT_PRIORITY = 1024;
 
+    // A metadata field is populated with a date (`\DateTimeImmutable`) under this key.
+    public const METADATA_SCHEDULED_KEY = '__scheduled__';
+
+    // A metadata field is populated with the priority (`int`) under this key.
+    public const METADATA_PRIORITY_KEY = '__priority__';
+
+    // A metadata field is populated with the ID of this job in the database (`int`) under this key.
+    public const METADATA_ID_KEY = '__id__';
+
     /**
      * Options for this queue
      *
@@ -193,8 +202,7 @@ public function pop(array $options = []): ?JobInterface
             return null;
         }
 
-        // Add job ID to meta data
-        return $this->unserializeJob($row['data'], ['__id__' => $row['id']]);
+        return $this->unserializeJobFromRow($row);
     }
 
     /**
@@ -313,8 +321,7 @@ public function peek(int $id): JobInterface
             throw new JobNotFoundException(sprintf("Job with id '%s' does not exists.", $id));
         }
 
-        // Add job ID to meta data
-        return $this->unserializeJob($row['data'], ['__id__' => $row['id']]);
+        return $this->unserializeJobFromRow($row);
     }
 
     /**
@@ -456,4 +463,16 @@ protected function purge(): void
             );
         }
     }
+
+    private function unserializeJobFromRow(array $row): JobInterface
+    {
+        return $this->unserializeJob(
+            $row['data'],
+            [
+                self::METADATA_ID_KEY => $row['id'],
+                self::METADATA_SCHEDULED_KEY => new \DateTimeImmutable($row['scheduled']),
+                self::METADATA_PRIORITY_KEY => $row['priority'],
+            ]
+        );
+    }
 }