Improve tag update

3 files changed, 29 insertions, 16 deletions

diff --git a/todo/db/task_tags.py b/todo/db/task_tags.py
index 0fae5f9..2f064e0 100644
--- a/todo/db/task_tags.py
+++ b/todo/db/task_tags.py
@@ -18,22 +18,31 @@ def get(cursor: Cursor) -> List[TaskTag]:
     return [TaskTag(r[0], r[1]) for r in cursor.fetchall()]
 
 def insert_many(cursor: Cursor, task_id: int, tag_ids: List[int]) -> List[TaskTag] :
-    now = int(time.time())
+    if len(tag_ids) >= 1:
+        now = int(time.time())
 
-    task_tags = [TaskTag(task_id = task_id, tag_id = tag) for tag in tag_ids]
+        task_tags = [TaskTag(task_id = task_id, tag_id = tag) for tag in tag_ids]
 
-    cursor.executemany(
-        " INSERT INTO task_tags("
-        "   task_id,"
-        "   tag_id,"
-        "   created_at"
-        " ) VALUES (?, ?, ?)",
-        [(t.task_id, t.tag_id, now) for t in task_tags])
+        cursor.executemany(
+            " INSERT INTO task_tags("
+            "   task_id,"
+            "   tag_id,"
+            "   created_at"
+            " ) VALUES (?, ?, ?)",
+            [(t.task_id, t.tag_id, now) for t in task_tags])
 
-    return task_tags
+        return task_tags
+    else:
+        return []
 
-def delete(cursor: Cursor, task_ids: List[int]):
+def delete_from_tasks(cursor: Cursor, task_ids: List[int]):
     if len(task_ids) >= 1:
         cursor.execute(
             "DELETE FROM task_tags WHERE task_id IN (%s)" % ",".join("?"*len(task_ids)),
             task_ids)
+
+def delete_from_tags(cursor: Cursor, task_id: int, tag_ids: List[int]):
+    if len(tag_ids) >= 1:
+        cursor.execute(
+            "DELETE FROM task_tags WHERE task_id = ? AND tag_id IN (%s)" % ",".join("?"*len(tag_ids)),
+            [task_id] + tag_ids)
diff --git a/todo/gui/tasks/dialog.py b/todo/gui/tasks/dialog.py
index c9e3734..2bed6af 100644
--- a/todo/gui/tasks/dialog.py
+++ b/todo/gui/tasks/dialog.py
@@ -19,7 +19,7 @@ def add(parent_widget, status: Status, add_task_signal):
 def update(parent_widget, update_task_signal, row: int, task: Task, tags: List[int]):
 
     def on_update(task_form: ValidTaskForm):
-        updated_task = todo.service.tasks.update(todo.database.cursor(), task, task_form)
+        updated_task = todo.service.tasks.update(todo.database.cursor(), task, tags, task_form)
         update_task_signal.emit(row, updated_task, task_form.tags)
 
     return widget(parent_widget, "Modify a task", "modify", task, tags, on_update)
diff --git a/todo/service/tasks.py b/todo/service/tasks.py
index 2cebf00..c01ab8a 100644
--- a/todo/service/tasks.py
+++ b/todo/service/tasks.py
@@ -15,15 +15,19 @@ def create(cursor, status: Status, task_form: ValidTaskForm) -> Task:
     todo.database.commit()
     return task
 
-def update(cursor, task: Task, task_form: ValidTaskForm) -> Task:
-    todo.db.task_tags.delete(cursor, [task.id])
+def update(cursor, task: Task, tags: List[int], task_form: ValidTaskForm) -> Task:
+    old_tags = [t for t in tags if t not in task_form.tags]
+    todo.db.task_tags.delete_from_tags(cursor, task.id, old_tags)
+
+    new_tags = [t for t in task_form.tags if t not in tags]
+    todo.db.task_tags.insert_many(cursor, task.id, new_tags)
+
     updated_task = todo.db.tasks.update(cursor, task, task_form)
-    todo.db.task_tags.insert_many(cursor, task.id, task_form.tags)
     todo.database.commit()
     return updated_task
 
 def delete(cursor, task_ids: List[int]):
-    todo.db.task_tags.delete(cursor, task_ids)
+    todo.db.task_tags.delete_from_tasks(cursor, task_ids)
     todo.db.tasks.delete(cursor, task_ids)
     todo.database.commit()