Handle possibly-missing users.

undercover/db.py

@@ -1,5 +1,6 @@
 import os
 from dataclasses import dataclass
+from typing import Optional
 
 import bcrypt
 import psycopg
@@ -43,7 +44,9 @@ def connected(action):
 def login(user_email: str, password: str):
     pw_bytes: bytes = password.encode('utf-8')
     user = __get_user(user_email)
+    if user:
         return bcrypt.checkpw(pw_bytes, user.password_hash.encode('utf-8'))
+    return False
 
 
 def add_user(username: str, password: str):
@@ -95,12 +98,14 @@ def get_user_letters(user_id: int) -> [Letter]:
         return list(map(lambda row: Letter(row[0], row[1], row[2]), cur.fetchall()))
 
 
-def get_user(email: str) -> User:
+def get_user(email: str) -> Optional[User]:
     user = __get_user(email)
+    if user:
         return User(user.id, user.email)
+    return None
 
 
-def __get_user(email: str) -> UserWithHash:
+def __get_user(email: str) -> Optional[UserWithHash]:
     """
     :param email:
     :return: User without their password_hash
@@ -108,8 +113,11 @@ def __get_user(email: str) -> UserWithHash:
     with connect() as con:
         cur = con.cursor()
         cur.execute("SELECT id, password FROM users WHERE users.email = %s", (email,))
-        user_id, password = cur.fetchone()
+        row = cur.fetchone()
+        if row:
+            user_id, password = row
             return UserWithHash(user_id, email, password)
+        return None
 
 
 def get_users() -> [UserWithHash]: