Fix Python 2/3 compatibility issue in base64 decoding

- Replace deprecated .decode("base64") with base64.b64decode() in short_id_to_bytes function
- Add import base64 to meta.py
- Add comprehensive unit tests for short_id_to_bytes and id_to_uuid functions
- Prevents AttributeError: 'str' object has no attribute 'decode' errors
- Resolves bad gateway authentication issues when accessing URLs with short IDs

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

make_post_sell/models/meta.py

@@ -1,4 +1,5 @@
 from time import time
+import base64
 
 from sqlalchemy import ForeignKey
 
@@ -74,7 +75,7 @@ def short_id_to_bytes(short_id):
     'u\xb1\xdeHAK\x11\xe7\xae\xcf\x9cN6\x9cqX'
 
     """
-    return (short_id + "==").replace("_", "/").replace("-", "+").decode("base64")
+    return base64.b64decode((short_id + "==").replace("_", "/").replace("-", "+"))
 
 
 def id_to_uuid(the_id):

make_post_sell/tests/test_models.py

@@ -1,9 +1,10 @@
 import unittest
+import uuid
 
 import mock
 
 from ..models import User, Coupon, Shop, is_user_name_valid
-from ..models.meta import now_timestamp
+from ..models.meta import now_timestamp, short_id_to_bytes, id_to_uuid
 
 mock_always_none = mock.Mock(return_value=None)
 mock_always_true = mock.Mock(return_value=True)
@@ -747,3 +748,69 @@ class TestProductS3Security(unittest.TestCase):
         self.assertFalse(self.product.is_public)
         self.assertFalse(self.product.is_unlisted)
         self.assertTrue(self.product.is_private)
+
+
+class TestMetaFunctions(unittest.TestCase):
+    """Test meta.py utility functions for base64 and UUID handling."""
+    
+    def test_short_id_to_bytes(self):
+        """Test short_id_to_bytes function converts base64 strings correctly."""
+        # Test case from the docstring
+        result = short_id_to_bytes('dbHeSEFLEeeuz5xONpxxWA')
+        expected = b'u\xb1\xdeHAK\x11\xe7\xae\xcf\x9cN6\x9cqX'
+        self.assertEqual(result, expected)
+        
+        # Test with various base64-encoded strings
+        test_cases = [
+            'YWJjZA',  # 'abcd' in base64
+            'dGVzdA',  # 'test' in base64 
+            'SGVsbG8',  # 'Hello' in base64
+        ]
+        
+        for test_case in test_cases:
+            # Should not raise an exception
+            result = short_id_to_bytes(test_case)
+            self.assertIsInstance(result, bytes)
+    
+    def test_id_to_uuid_with_short_id(self):
+        """Test id_to_uuid function works with short base64 IDs."""
+        # Test case from the docstring
+        result = id_to_uuid('dbHeSEFLEeeuz5xONpxxWA')
+        expected = uuid.UUID('75b1de48-414b-11e7-aecf-9c4e369c7158')
+        self.assertEqual(result, expected)
+    
+    def test_id_to_uuid_with_hex_string(self):
+        """Test id_to_uuid function works with hex UUID strings."""
+        # Test case from the docstring
+        result = id_to_uuid('75b1de48414b11e7aecf9c4e369c7158')
+        expected = uuid.UUID('75b1de48-414b-11e7-aecf-9c4e369c7158')
+        self.assertEqual(result, expected)
+    
+    def test_id_to_uuid_with_dashed_uuid(self):
+        """Test id_to_uuid function works with dashed UUID strings."""
+        # Test case from the docstring
+        result = id_to_uuid('75b1de48-414b-11e7-aecf-9c4e369c7158')
+        expected = uuid.UUID('75b1de48-414b-11e7-aecf-9c4e369c7158')
+        self.assertEqual(result, expected)
+    
+    def test_id_to_uuid_with_uuid_object(self):
+        """Test id_to_uuid function returns UUID objects unchanged."""
+        test_uuid = uuid.UUID('75b1de48-414b-11e7-aecf-9c4e369c7158')
+        result = id_to_uuid(test_uuid)
+        self.assertEqual(result, test_uuid)
+        self.assertIs(result, test_uuid)  # Should be the same object
+    
+    def test_id_to_uuid_with_invalid_input(self):
+        """Test id_to_uuid function returns None for invalid input."""
+        result = id_to_uuid('invalid-input')
+        self.assertIsNone(result)
+        
+        result = id_to_uuid('')
+        self.assertIsNone(result)
+    
+    def test_id_to_uuid_with_none_raises_typeerror(self):
+        """Test id_to_uuid function raises TypeError for None input."""
+        # None input causes TypeError in uuid.UUID, not ValueError,
+        # so it's not caught by the exception handlers
+        with self.assertRaises(TypeError):
+            id_to_uuid(None)