* Help me check that the PR has **tests**.

* Check that the tests **fail** before the PR. 🚨

* Then check that the tests **pass** after the PR. ✅

* Many PRs don't have tests, you can **remind** them to add tests, or you can even **suggest** some tests yourself. That's one of the things that consume most time and you can help a lot with that.

* Then also comment what you tried, that way I'll know that you checked it. 🤓

...
```

#### What is OpenAPI for { #what-is-openapi-for }

The OpenAPI schema is what powers the two interactive documentation systems included.

And there are dozens of alternatives, all based on OpenAPI. You could easily add any of those alternatives to your application built with **FastAPI**.

This decoupling of parts, and being a "microframework" that could be extended to cover exactly what is needed was a key feature that I wanted to keep.

Given the simplicity of Flask, it seemed like a good match for building APIs. The next thing to find was a "Django REST Framework" for Flask.

/// check | Inspired **FastAPI** to

* **Nhanh**: Hiệu năng rất cao khi so sánh với **NodeJS** và **Go** (cảm ơn Starlette và Pydantic). [Một trong những Python framework nhanh nhất](#hieu-nang).
* **Code nhanh**: Tăng tốc độ phát triển tính năng từ 200% tới 300%. *
* **Ít lỗi hơn**: Giảm khoảng 40% những lỗi phát sinh bởi con người (nhà phát triển). *

### FastAPI Data Filtering { #fastapi-data-filtering }

Now, for FastAPI, it will see the return type and make sure that what you return includes **only** the fields that are declared in the type.

* `Field(index=True)` tells SQLModel that it should create a **SQL index** for this column, that would allow faster lookups in the database when reading data filtered by this column.

    SQLModel will know that something declared as `str` will be a SQL column of type `TEXT` (or `VARCHAR`, depending on the database).

////

/// tip

Every time you install a **new package** in that environment, **activate** the environment again.

This makes sure that if you use a **terminal (<abbr title="command line interface">CLI</abbr>) program** installed by that package, you use the one from your virtual environment and not any other that could be installed globally, probably with a different version than what you need.

///

## What is a Container Image { #what-is-a-container-image }

A **container** is run from a **container image**.

## Context Managers { #context-managers }

### What are "Context Managers" { #what-are-context-managers }

"Context Managers" are any of those Python objects that you can use in a `with` statement.

<img src="/img/deployment/https/https03.drawio.svg">

The client already **trusts** the entity that generated that TLS certificate (in this case Let's Encrypt, but we'll see about that later), so it can **verify** that the certificate is valid.