feat: Use content_id for inline attachments (#118)

Author: drish

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    resend (0.22.0)
+    resend (0.23.0)
       httparty (>= 0.21.0)
 
 GEM

examples/with_attachments.rb

@@ -38,7 +38,7 @@
     {
       "path": "https://resend.com/static/brand/resend-wordmark-black.png",
       "filename": "resend-wordmark-black.png",
-      "inline_content_id": "image"
+      "content_id": "image"
     }
   ]
 }

lib/resend/mailer.rb

@@ -221,7 +221,7 @@ def get_attachments(mail)
         }
 
         # Rails uses the auto generated cid for inline attachments
-        attachment[:inline_content_id] = part.cid if part.inline?
+        attachment[:content_id] = part.cid if part.inline?
         attachments.append(attachment)
       end
       attachments

spec/railtie/mailer_spec.rb

@@ -153,7 +153,7 @@ class TestMailerWithDisplayName < TestMailer
     expect(body[:attachments].length).to eql(1)
     expect(body[:attachments].first[:filename]).to eql("invoice.pdf")
     expect(body[:attachments].first[:content].length > 0).to be true
-    expect(body[:attachments].first[:inline_content_id]).to be_nil
+    expect(body[:attachments].first[:content_id]).to be_nil
   end
 
   it "properly creates a html text with inline attachments msg" do
@@ -166,7 +166,7 @@ class TestMailerWithDisplayName < TestMailer
     expect(body[:attachments].length).to eql(1)
     expect(body[:attachments].first[:filename]).to eql("logo.png")
     expect(body[:attachments].first[:content].length > 0).to be true
-    expect(body[:attachments].first[:inline_content_id]).to_not be_nil
+    expect(body[:attachments].first[:content_id]).to_not be_nil
   end
 
   it "properly handles from display name" do