Exception handling for database commit operations

ref-test/app/models/user.py

@@ -7,6 +7,7 @@ from flask.helpers import url_for
 from flask_login import current_user, login_user, logout_user, UserMixin
 from flask_mail import Message
 from smtplib import SMTPException
+from sqlalchemy.exc import SQLAlchemyError
 from werkzeug.security import check_password_hash, generate_password_hash
 
 import secrets
@@ -61,8 +62,13 @@ class User(UserMixin, db.Model):
             if user.get_username() == self.get_username(): return False, f'Username {self.get_username()} already in use.'
             if user.get_email() == self.get_email(): return False, f'Email address {self.get_email()} already in use.'
         self.set_password(password=password)
-        db.session.add(self)
-        db.session.commit()
+        try:
+            db.session.add(self)
+            db.session.commit()
+        except SQLAlchemyError as exception:
+            db.session.rollback()
+            write('system.log', f'Database error when registering user {self.get_username()}: {exception}')
+            return False, f'Database error: {exception}'
         write('users.log', f'User \'{self.get_username()}\' was created with id \'{self.id}\'.')
         if notify:
             email = Message(
@@ -149,19 +155,35 @@ class User(UserMixin, db.Model):
             mail.send(email)
         except SMTPException as exception:
             write('system.log', f'SMTP Error while trying to reset password for {self.get_username()} with error: {exception}')
+            db.session.rollback()
             return jsonify({'error': f'SMTP Error: {exception}'}), 500
-        db.session.commit()
+        try:
+            db.session.commit()
+        except SQLAlchemyError as exception:
+            db.session.rollback()
+            write('system.log', f'Database error when resetting password for user {self.get_username()}: {exception}')
+            return False, f'Database error: {exception}'
         return jsonify({'success': 'Your password reset link has been generated.'}), 200
 
     def clear_reset_tokens(self):
         self.reset_token = self.verification_token = None
-        db.session.commit()
+        try:
+            db.session.commit()
+        except SQLAlchemyError as exception:
+            db.session.rollback()
+            write('system.log', f'Database error when resetting clearing reset tokens for user {self.get_username()}: {exception}')
+            return False, f'Database error: {exception}'
     
     def delete(self, notify:bool=False):
         username = self.get_username()
         email_address = self.get_email()
-        db.session.delete(self)
-        db.session.commit()
+        try:
+            db.session.delete(self)
+            db.session.commit()
+        except SQLAlchemyError as exception:
+            db.session.rollback()
+            write('system.log', f'Database error when deleting user {self.get_username()}: {exception}')
+            return False, f'Database error: {exception}'
         message = f'User \'{username}\' was deleted by \'{current_user.get_username()}\'.'
         write('users.log', message)
         if notify:
@@ -200,7 +222,12 @@ class User(UserMixin, db.Model):
             for entry in User.query.all():
                 if entry.get_email() == email and not entry == self: return False, f'The email address {email} is already in use.'
             self.set_email(email)
-        db.session.commit()
+        try:
+            db.session.commit()
+        except SQLAlchemyError as exception:
+            db.session.rollback()
+            write('system.log', f'Database error when updating user {self.get_username()}: {exception}')
+            return False, f'Database error: {exception}'
         _current_user = current_user.get_username() if current_user.is_authenticated else 'anonymous'
         write('system.log', f'Information for user {self.get_username()} has been updated by {_current_user}.')
         if notify: