From 427f62acca946cc0f12cd167028c580a920db315 Mon Sep 17 00:00:00 2001
From: Yuyao Huang <huangyuyao@outlook.com>
Date: Sat, 9 May 2026 13:05:53 +0800
Subject: [PATCH] fix: handle foreign key constraint when deleting tasks with
 selected_task_id refs

Goals table has selected_task_id referencing tasks(id) without
ON DELETE SET NULL. When deleting a task, first clear any
selected_task_id references in goals to prevent FK violation.

Also update schema for future databases.
---
 database.py | 1 +
 schema.py   | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/database.py b/database.py
index b6a93e3..13db531 100644
--- a/database.py
+++ b/database.py
@@ -190,6 +190,7 @@ def update_task(task_id, **kwargs):
 def delete_task(task_id):
     conn = get_connection()
     try:
+        conn.execute('UPDATE goals SET "selected_task_id" = NULL WHERE "selected_task_id" = ?', (task_id,))
         conn.execute("DELETE FROM tasks WHERE id = ?", (task_id,))
         conn.commit()
     finally:
diff --git a/schema.py b/schema.py
index a9e1f02..53c092c 100644
--- a/schema.py
+++ b/schema.py
@@ -22,7 +22,7 @@ CREATE TABLE IF NOT EXISTS goals (
     activated INTEGER NOT NULL DEFAULT 1,
     selected_task_id INTEGER,
     FOREIGN KEY (user_id) REFERENCES users(id),
-    FOREIGN KEY (selected_task_id) REFERENCES tasks(id)
+    FOREIGN KEY (selected_task_id) REFERENCES tasks(id) ON DELETE SET NULL
 )
 """