FIX: Shrinking images where smaller image upload exists (#18965)

app/models/post.rb

@@ -989,10 +989,6 @@ class Post < ActiveRecord::Base
     end
   end
 
-  def downloaded_images
-    self.custom_fields[Post::DOWNLOADED_IMAGES] || {}
-  end
-
   def each_upload_url(fragments: nil, include_local_upload: true)
     current_db = RailsMultisite::ConnectionManagement.current_db
     upload_patterns = [

lib/shrink_uploaded_image.rb

@@ -83,7 +83,7 @@ class ShrinkUploadedImage
 
       if post.raw_changed?
         log "Updating post"
-      elsif post.downloaded_images.has_value?(original_upload.id)
+      elsif post.post_hotlinked_media.exists?(upload_id: original_upload.id)
         log "A hotlinked, unreferenced image"
       elsif post.raw.include?(upload.short_url)
         log "Already processed"
@@ -161,13 +161,10 @@ class ShrinkUploadedImage
           )
         end
 
-        if existing_upload && post.downloaded_images.present?
-          downloaded_images = post.downloaded_images.transform_values do |upload_id|
-            upload_id == original_upload.id ? upload.id : upload_id
-          end
-
-          post.custom_fields[Post::DOWNLOADED_IMAGES] = downloaded_images
-          post.save_custom_fields
+        if existing_upload
+          post.post_hotlinked_media
+            .where(upload_id: original_upload.id)
+            .update_all(upload_id: upload.id)
         end
 
         post.rebake!

spec/lib/shrink_uploaded_image_spec.rb

@@ -21,6 +21,29 @@ RSpec.describe ShrinkUploadedImage do
       expect(upload.filesize).to be < filesize_before
     end
 
+    it "updates HotlinkedMedia records when there is an upload for downsized image" do
+      OptimizedImage.downsize(Discourse.store.path_for(upload), "/tmp/smaller.png", "10000@", filename: upload.original_filename)
+      smaller_sha1 = Upload.generate_digest("/tmp/smaller.png")
+      smaller_upload = Fabricate(:image_upload, sha1: smaller_sha1)
+
+      post = Fabricate(:post, raw: "<img src='#{upload.url}'>")
+      post.link_post_uploads
+      post_hotlinked_media = PostHotlinkedMedia.create!(
+        post: post,
+        url: "http://example.com/images/2/2e/Longcat1.png",
+        upload: upload,
+        status: :downloaded,
+      )
+
+      ShrinkUploadedImage.new(
+        upload: upload,
+        path: Discourse.store.path_for(upload),
+        max_pixels: 10_000,
+      ).perform
+
+      expect(post_hotlinked_media.reload.upload).to eq(smaller_upload)
+    end
+
     it "returns false if the image is not used by any models" do
       result = ShrinkUploadedImage.new(
         upload: upload,