Implementing dependency injection

Dependency injection is a powerful design pattern used in software development to manage dependencies between components. In the context of FastAPI, dependency injection allows you to efficiently manage and inject dependencies, such as database connections, authentication services, and configuration settings, into your application’s endpoints and middleware. Although we have already used dependency injection in previous recipes, such as Setting up SQL databases in Chapter 2, Working with Data, or Setting up user registration in Chapter 4, Authentication and Authorization, this recipe will show you how to implement dependency injections in FastAPI and how to tackle trickier use cases with nested dependency injections.

Getting ready

To follow along with the recipe, you only need to have Python installed with the fastapi and uvicorn packages installed in your environment, as well as pytest. If you haven’t installed the packages with...