Refactor to move common logic to the base class

neon_users_service/databases/__init__.py

@@ -1,18 +1,30 @@
 from abc import ABC, abstractmethod
 
-from neon_users_service.exceptions import UserNotFoundError
+from neon_users_service.exceptions import UserNotFoundError, UserExistsError
 from neon_data_models.models.user.database import User
 
 
 class UserDatabase(ABC):
-    @abstractmethod
     def create_user(self, user: User) -> User:
         """
         Add a new user to the database. Raises a `UserExistsError` if the input
         `user` already exists in the database (by `username` or `user_id`).
         @param user: `User` object to insert to the database
         @return: `User` object inserted into the database
         """
+        if self._check_user_exists(user):
+            raise UserExistsError(user)
+        return self._db_create_user(user)
+
+    @abstractmethod
+    def _db_create_user(self, user: User) -> User:
+        """
+        Add a new user to the database. The `user` object has already been
+        validated as unique, so this just needs to perform the database
+        transaction.
+        @param user: `User` object to insert to the database
+        @return: `User` object inserted into the database
+        """
 
     @abstractmethod
     def read_user_by_id(self, user_id: str) -> User:
@@ -45,14 +57,33 @@ def read_user(self, user_spec: str) -> User:
         except UserNotFoundError:
             return self.read_user_by_username(user_spec)
 
-    @abstractmethod
     def update_user(self, user: User) -> User:
         """
         Update a user entry in the database. Raises a `UserNotFoundError` if
         the input user's `user_id` is not found in the database.
+        @param user: `User` object to update in the database
+        @return: Updated `User` object read from the database
         """
+        # Lookup user to ensure they exist in the database
+        existing_id = self.read_user_by_id(user.user_id)
+        try:
+            if self.read_user_by_username(user.username) != existing_id:
+                raise UserExistsError(f"Another user with username "
+                                      f"'{user.username}' already exists")
+        except UserNotFoundError:
+            pass
+        return self._db_update_user(user)
 
     @abstractmethod
+    def _db_update_user(self, user: User) -> User:
+        """
+        Update a user entry in the database. The `user` object has already been
+        validated as existing and changes valid, so this just needs to perform
+        the database transaction.
+        @param user: `User` object to update in the database
+        @return: Updated `User` object read from the database
+        """
+
     def delete_user(self, user_id: str) -> User:
         """
         Remove a user from the database if it exists. Raises a
@@ -61,6 +92,19 @@ def delete_user(self, user_id: str) -> User:
         @param user_id: `user_id` to remove
         @return: User object removed from the database
         """
+        # Lookup user to ensure they exist in the database
+        user_to_delete = self.read_user_by_id(user_id)
+        return self._db_delete_user(user_to_delete)
+
+    @abstractmethod
+    def _db_delete_user(self, user: User) -> User:
+        """
+        Remove a user from the database if it exists. The `user` object has
+        already been validated as existing, so this just needs to perform the
+        database transaction.
+        @param user: User object to remove
+        @return: User object removed from the database
+        """
 
     def _check_user_exists(self, user: User) -> bool:
         """

neon_users_service/databases/sqlite.py

@@ -2,12 +2,12 @@
 
 from os import makedirs
 from os.path import expanduser, dirname
-from sqlite3 import connect, Cursor
+from sqlite3 import connect
 from threading import Lock
 from typing import Optional, List
 
 from neon_users_service.databases import UserDatabase
-from neon_users_service.exceptions import UserNotFoundError, UserExistsError, DatabaseError
+from neon_users_service.exceptions import UserNotFoundError, DatabaseError
 from neon_data_models.models.user.database import User
 
 
@@ -26,9 +26,7 @@ def __init__(self, db_path: Optional[str] = None):
         )
         self.connection.commit()
 
-    def create_user(self, user: User) -> User:
-        if self._check_user_exists(user):
-            raise UserExistsError(user)
+    def _db_create_user(self, user: User) -> User:
         with self._db_lock:
             self.connection.execute(
                 f'''INSERT INTO users VALUES 
@@ -72,15 +70,7 @@ def read_user_by_username(self, username: str) -> User:
             cursor.close()
         return User(**json.loads(self._parse_lookup_results(username, rows)))
 
-    def update_user(self, user: User) -> User:
-        # Lookup user to ensure they exist in the database
-        existing_id = self.read_user_by_id(user.user_id)
-        try:
-            if self.read_user_by_username(user.username) != existing_id:
-                raise UserExistsError(f"Another user with username "
-                                      f"'{user.username}' already exists")
-        except UserNotFoundError:
-            pass
+    def _db_update_user(self, user: User) -> User:
         with self._db_lock:
             self.connection.execute(
                 f'''UPDATE users SET username = '{user.username}',
@@ -91,13 +81,12 @@ def update_user(self, user: User) -> User:
             self.connection.commit()
         return self.read_user_by_id(user.user_id)
 
-    def delete_user(self, user_id: str) -> User:
-        # Lookup user to ensure they exist in the database
-        user_to_delete = self.read_user_by_id(user_id)
+    def _db_delete_user(self, user: User) -> User:
         with self._db_lock:
-            self.connection.execute(f"DELETE FROM users WHERE user_id = '{user_id}'")
+            self.connection.execute(
+                f"DELETE FROM users WHERE user_id = '{user.user_id}'")
             self.connection.commit()
-        return user_to_delete
+        return user
 
     def shutdown(self):
         self.connection.close()