user: How to setup authorization and authentication fastapi with explaination ?

assistant: Sure, here's an overview of how to set up authorization and authentication in FastAPI:

1. Install the necessary dependencies: You'll need to install the fastapi-users and passlib[bcrypt] packages. These packages provide authentication and password hashing functionality, respectively.
2. Create a user model: In your FastAPI app, define a user model that inherits from the BaseUser class provided by fastapi-users. This model should include any fields you want to store for your users, such as username, email, and password.
3. Create a user database: You'll need a database to store your users. You can use any database supported by SQLAlchemy, such as PostgreSQL, MySQL, or SQLite. Create a new database and add your user model to it.
4. Create an authentication backend: This backend will be responsible for verifying user credentials and returning a user object if authentication succeeds. You can create a backend by subclassing the BaseAuthenticationBackend class provided by fastapi-users.
5. Define authentication routes: In your FastAPI app, define routes for handling user authentication. These routes should accept user credentials (such as username and password) and pass them to your authentication backend for verification.
6. Create an authorization backend: This backend will be responsible for determining whether a user has permission to perform a certain action (such as accessing a protected resource). You can create a backend by subclassing the BaseAuthorizationBackend class provided by fastapi-users.
7. Define authorization rules: In your FastAPI app, define rules for determining whether a user is authorized to perform a certain action. These rules should take into account the user's role or other relevant attributes.

Here's a brief overview of the key concepts involved in setting up authorization and authentication in FastAPI:
- Authentication: The process of verifying a user's identity. This typically involves checking user credentials (such as username and password) against a stored database of user accounts.
- Authorization: The process of determining whether a user is allowed to perform a certain action. This typically involves checking the user's role or other relevant attributes against a set of predefined rules.
- Token-based authentication: A method of authentication that involves issuing a token (such as a JSON Web Token or JWT) to a user after they have successfully authenticated. This token can be used to authenticate subsequent requests without requiring the user to re-enter their credentials.
- Bearer token: A type of token used in token-based authentication, where the token is passed as a bearer token in the Authorization header of HTTP requests.
- Password hashing: The process of converting a user's password into a hashed value that can be safely stored in a database. This ensures that even if an attacker gains access to the database, they cannot easily recover users' passwords.
- SQLAlchemy: A popular Python library for working with databases. FastAPI integrates with SQLAlchemy to provide a flexible and powerful way to work with databases.

user: Does SQLAlchemy provide any input sanitization, or would I need to implement that myself?

assistant: SQLAlchemy does not provide input sanitization out of the box, as it is not directly responsible for handling user input. Instead, SQLAlchemy is a tool for working with databases and provides a way to define models and perform database operations in a Pythonic way.

However, SQLAlchemy does provide some protection against SQL injection attacks, which are a common type of attack that targets databases. SQLAlchemy automatically escapes any special characters in user input when performing database operations, which helps to prevent SQL injection attacks.

That being said, it's important to note that input sanitization is an important part of securing your application against various types of attacks. While SQLAlchemy can help protect against SQL injection attacks, you should still implement input sanitization measures in your application to ensure that all user input is properly validated and sanitized before being processed or stored.