Merge pull request rails#53770 from Earlopain/aj-deserialization-name-error

Raise a more specific error when the job class can't be instantiated

Author: byroot

activejob/CHANGELOG.md

@@ -1,2 +1,9 @@
+*   Raise a more specific error during deserialization when a previously serialized job class is now unknown.
+
+    `ActiveJob::UnknownJobClassError` will be raised instead of a more generic
+    `NameError` to make it easily possible for adapters to tell if the `NameError`
+    was raised during job execution or deserialization.
+
+    *Earlopain*
 
 Please check [8-0-stable](https://github.com/rails/rails/blob/8-0-stable/activejob/CHANGELOG.md) for previous changes.

activejob/lib/active_job.rb

@@ -39,6 +39,7 @@ module ActiveJob
   autoload :Arguments
   autoload :DeserializationError, "active_job/arguments"
   autoload :SerializationError, "active_job/arguments"
+  autoload :UnknownJobClassError, "active_job/core"
   autoload :EnqueueAfterTransactionCommit
 
   eager_autoload do

activejob/lib/active_job/core.rb

@@ -1,6 +1,13 @@
 # frozen_string_literal: true
 
 module ActiveJob
+  # Raised during job payload deserialization when it references an uninitialized job class.
+  class UnknownJobClassError < NameError
+    def initialize(job_class_name)
+      super("Failed to instantiate job, class `#{job_class_name}` doesn't exist", job_class_name)
+    end
+  end
+
   # = Active Job \Core
   #
   # Provides general behavior that will be included into every Active Job
@@ -60,7 +67,10 @@ def successfully_enqueued?
     module ClassMethods
       # Creates a new job instance from a hash created with +serialize+
       def deserialize(job_data)
-        job = job_data["job_class"].constantize.new
+        job_class = job_data["job_class"].safe_constantize
+        raise UnknownJobClassError, job_data["job_class"] unless job_class
+
+        job = job_class.new
         job.deserialize(job_data)
         job
       end

activejob/test/cases/job_serialization_test.rb

@@ -38,6 +38,17 @@ class JobSerializationTest < ActiveSupport::TestCase
     assert_equal h2.serialize, h3.serialize
   end
 
+  test "deserialize raises a specific exception on unknown `job_class`" do
+    payload = HelloJob.new.serialize
+
+    # Simulate the job class being missing, for example during rolling deploys when
+    # the server enqueues a new job but the job processor hasn't been restarted yet.
+    payload["job_class"] = "IDontExist"
+    assert_raises(ActiveJob::UnknownJobClassError) do
+      HelloJob.deserialize(payload)
+    end
+  end
+
   test "deserialize sets locale" do
     job = HelloJob.new
     job.deserialize "locale" => "es"