diff --git a/.gitignore b/.gitignore
index c733c37..d5c080a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,6 @@
 product_management.egg-info/
 __pycache__/
+*.pyc
+*.pyo
+*.egg-info/
+.DS_Store
diff --git a/models/product_category.json b/models/product_category.json
index da3115e..66b39f6 100644
--- a/models/product_category.json
+++ b/models/product_category.json
@@ -21,7 +21,8 @@
             "name": "parent_id",
             "title": "父类别ID",
             "type": "str",
-            "length": 32
+            "length": 32,
+            "nullable": "yes"
         },
         {
             "name": "name",
diff --git a/product_management.egg-info/PKG-INFO b/product_management.egg-info/PKG-INFO
deleted file mode 100644
index c1d3aec..0000000
--- a/product_management.egg-info/PKG-INFO
+++ /dev/null
@@ -1,7 +0,0 @@
-Metadata-Version: 2.4
-Name: product_management
-Version: 1.0.0
-Summary: Sage product management module - dynamic category tree, product registry, operator config, standardized API
-Requires-Python: >=3.8
-Requires-Dist: sqlor
-Requires-Dist: bricks_for_python
diff --git a/product_management.egg-info/SOURCES.txt b/product_management.egg-info/SOURCES.txt
deleted file mode 100644
index d52c828..0000000
--- a/product_management.egg-info/SOURCES.txt
+++ /dev/null
@@ -1,10 +0,0 @@
-README.md
-pyproject.toml
-product_management/__init__.py
-product_management/core.py
-product_management/init.py
-product_management.egg-info/PKG-INFO
-product_management.egg-info/SOURCES.txt
-product_management.egg-info/dependency_links.txt
-product_management.egg-info/requires.txt
-product_management.egg-info/top_level.txt
\ No newline at end of file
diff --git a/product_management.egg-info/dependency_links.txt b/product_management.egg-info/dependency_links.txt
deleted file mode 100644
index 8b13789..0000000
--- a/product_management.egg-info/dependency_links.txt
+++ /dev/null
@@ -1 +0,0 @@
-
diff --git a/product_management.egg-info/requires.txt b/product_management.egg-info/requires.txt
deleted file mode 100644
index 3f3a3f3..0000000
--- a/product_management.egg-info/requires.txt
+++ /dev/null
@@ -1,2 +0,0 @@
-sqlor
-bricks_for_python
diff --git a/product_management.egg-info/top_level.txt b/product_management.egg-info/top_level.txt
deleted file mode 100644
index 5461594..0000000
--- a/product_management.egg-info/top_level.txt
+++ /dev/null
@@ -1 +0,0 @@
-product_management
diff --git a/wwwroot/api/product_category_create.dspy b/wwwroot/api/product_category_create.dspy
index 0fe2697..b83071d 100644
--- a/wwwroot/api/product_category_create.dspy
+++ b/wwwroot/api/product_category_create.dspy
@@ -12,7 +12,7 @@ try:
     data['created_at'] = timestampstr()
     data['updated_at'] = timestampstr()
     if 'parent_id' not in data or not data['parent_id']:
-        data['parent_id'] = '0'
+        data['parent_id'] = None
     if 'has_product' not in data:
         data['has_product'] = '0'
     if 'status' not in data:
@@ -21,7 +21,7 @@ try:
         data['sort_order'] = '0'
 
     # Validate parent belongs to same org
-    if data['parent_id'] != '0':
+    if data['parent_id'] is not None:
         check_sql = "SELECT id FROM product_category WHERE id = ${parent_id}$ AND org_id = ${org_id}$"
         async with DBPools().sqlorContext(dbname) as sor:
             rows = await sor.sqlExe(check_sql, {'parent_id': data['parent_id'], 'org_id': org_id})
diff --git a/wwwroot/api/product_category_update.dspy b/wwwroot/api/product_category_update.dspy
index 19d84ea..1402547 100644
--- a/wwwroot/api/product_category_update.dspy
+++ b/wwwroot/api/product_category_update.dspy
@@ -21,6 +21,11 @@ try:
 
     data['updated_at'] = timestampstr()
     data['id'] = record_id
+
+    # Convert empty parent_id to NULL for tree root nodes
+    if 'parent_id' in data and not data['parent_id']:
+        data['parent_id'] = None
+
     if data.get('has_product') == '0':
         data['product_type'] = ''
         data['product_type_title'] = ''