backend/app/controllers/posts_controller.rb

@@ -81,7 +81,7 @@ class PostsController < ApplicationController
     # TODO: URL が正規のものがチェック，不正ならエラー
     # TODO: URL は必須にする（タイトルは省略可）．
     # TODO: サイトに応じて thumbnail_base 設定
-    title = params[:title]
+    title = params[:title].presence
     url = params[:url]
     thumbnail = params[:thumbnail]
     tag_names = params[:tags].to_s.split(' ')
@@ -122,7 +122,7 @@ class PostsController < ApplicationController
     return head :unauthorized unless current_user
     return head :forbidden unless current_user.member?
 
-    title = params[:title]
+    title = params[:title].presence
     tag_names = params[:tags].to_s.split(' ')
     original_created_from = params[:original_created_from]
     original_created_before = params[:original_created_before]

backend/db/migrate/20260107034300_make_title_nullable_in_posts.rb

@@ -0,0 +1,28 @@
+class MakeTitleNullableInPosts < ActiveRecord::Migration[7.0]
+  def up
+    change_column_null :posts, :title, true
+
+    execute <<~SQL
+      UPDATE
+        posts
+      SET
+        title = NULL
+      WHERE
+        title = ''
+    SQL
+  end
+
+  def down
+    execute <<~SQL
+      UPDATE
+        posts
+      SET
+        title = ''
+      WHERE
+        title IS NULL
+    SQL
+
+    change_column_null :posts, :title, false
+  end
+end
+

backend/db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2025_12_30_143400) do
+ActiveRecord::Schema[8.0].define(version: 2026_01_07_034300) do
   create_table "active_storage_attachments", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
     t.string "name", null: false
     t.string "record_type", null: false
@@ -84,7 +84,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_12_30_143400) do
   end
 
   create_table "posts", charset: "utf8mb4", collation: "utf8mb4_0900_ai_ci", force: :cascade do |t|
-    t.string "title", null: false
+    t.string "title"
     t.string "url", limit: 2000, null: false
     t.string "thumbnail_base", limit: 2000
     t.bigint "parent_id"