Add :allow_nil option to delegate_missing_to; use in ActiveStorage

attachment

2 files changed, 16 insertions, 1 deletions

diff --git a/activestorage/CHANGELOG.md b/activestorage/CHANGELOG.md
index 1a03ead870..351d8687a4 100644
--- a/activestorage/CHANGELOG.md
+++ b/activestorage/CHANGELOG.md
@@ -1,3 +1,18 @@
+*  Method calls on singular attachments return `nil` when no file is attached.
+
+   Previously, assuming the following User model, `user.avatar.filename` would 
+   raise a `Module::DelegationError` if no avatar was attached:
+
+   ```ruby
+   class User < ApplicationRecord
+     has_one_attached :avatar
+   end
+   ```
+   
+   They now return `nil`.
+
+   *Matthew Tanous*
+
 *  The mirror service supports direct uploads.
 
    New files are directly uploaded to the primary service. When a
diff --git a/activestorage/lib/active_storage/attached/one.rb b/activestorage/lib/active_storage/attached/one.rb
index c039226fcd..003be1cb43 100644
--- a/activestorage/lib/active_storage/attached/one.rb
+++ b/activestorage/lib/active_storage/attached/one.rb
@@ -3,7 +3,7 @@
 module ActiveStorage
   # Representation of a single attachment to a model.
   class Attached::One < Attached
-    delegate_missing_to :attachment
+    delegate_missing_to :attachment, allow_nil: true
 
     # Returns the associated attachment record.
     #