#399

backend/app/controllers/posts_controller.rb

@@ -137,6 +137,7 @@ class PostsController < ApplicationController
           video_ms: nil,
           field_warnings: { },
           base_warnings: [],
+          existing_post_id: existing_post.id,
           existing_post: compact_post(existing_post.id) }
     end
 
@@ -158,6 +159,7 @@ class PostsController < ApplicationController
         video_ms: metadata[:video_ms],
         field_warnings: field_warnings,
         base_warnings: [],
+        existing_post_id: nil,
         existing_post: nil }
   rescue ArgumentError => e
     render_bad_request e.message
@@ -177,6 +179,7 @@ class PostsController < ApplicationController
         video_ms: nil,
         field_warnings: { url: ['自動取得に失敗しました．'] },
         base_warnings: [],
+        existing_post_id: nil,
         existing_post: nil }
   end
 
@@ -212,7 +215,7 @@ class PostsController < ApplicationController
         attributes: post_create_attributes,
         thumbnail: params[:thumbnail]).run
     return render json: dry_run_json(preflight) if bool?(:dry)
-    if preflight[:existing_post].present?
+    if preflight[:existing_post_id].present?
       post = Post.new(url: preflight[:url])
       post.errors.add :url, :taken
       return render_post_form_record_invalid post
@@ -637,6 +640,7 @@ class PostsController < ApplicationController
         :video_ms,
         :field_warnings,
         :base_warnings,
+        :existing_post_id,
         :existing_post)
   end