#306

backend/app/controllers/materials_controller.rb

@@ -95,8 +95,7 @@ class MaterialsController < ApplicationController
     end
 
     if material
-      MaterialThumbnailGenerator.generate!(material)
-      material.reload
+      log_thumbnail_generation(material, MaterialThumbnailGenerator.generate!(material))
       render json: MaterialRepr.base(material, host: request.base_url), status: :created
     else
       render_validation_error material
@@ -147,8 +146,7 @@ class MaterialsController < ApplicationController
       raise
     end
 
-    MaterialThumbnailGenerator.generate!(material)
-    material.reload
+    log_thumbnail_generation(material, MaterialThumbnailGenerator.generate!(material))
 
     render json: MaterialRepr.base(material, host: request.base_url)
   end
@@ -375,4 +373,13 @@ class MaterialsController < ApplicationController
   def render_material_import_block block
     render_validation_error fields: { file: ["抑止された素材です: #{ block.reason }"] }
   end
+
+  def log_thumbnail_generation material, result
+    material.reload
+    Rails.logger.info(
+        "Material thumbnail generation: material_id=#{ material.id } " \
+        "result=#{ result } " \
+        "thumbnail_attached=#{ material.thumbnail.attached? } " \
+        "content_type=#{ material.content_type }")
+  end
 end