* 🐛 Fix overriding MKDocs theme lang in hook. PR [#10490](https://github.com/tiangolo/fastapi/pull/10490) by [@tiangolo](https://github.com/tiangolo).
* 🔥 Drop/close Gitter chat. Questions should go to GitHub Discussions, free conversations to Discord.. PR [#10485](https://github.com/tiangolo/fastapi/pull/10485) by [@tiangolo](https://github.com/tiangolo).

## 0.104.0

## Features

👆 💪 🔎 🖼 ⚗ FastAPI 🏗 📄 ⚪️➡️ [🏗 ⚡ - 📄](../project-generation.md){.internal-link target=_blank}. 🎯 <a href="https://github.com/tiangolo/full-stack-fastapi-postgresql/tree/master/src/backend/app/alembic/" class="external-link" target="_blank"> `alembic` 📁 ℹ 📟</a>.

### ✍ 🔗

🔜 ⚙️ `SessionLocal` 🎓 👥 ✍ `sql_app/database.py` 📁 ✍ 🔗.

OAuth2 doesn't specify how to encrypt the communication, it expects you to have your application served with HTTPS.

!!! tip
    In the section about **deployment** you will see how to set up HTTPS for free, using Traefik and Let's Encrypt.


## OpenID Connect

OpenID Connect is another specification, based on **OAuth2**.

    Use the chat only for other general conversations.

### Don't use the chat for questions

Keep in mind that as chats allow more "free conversation", it's easy to ask questions that are too general and more difficult to answer, so, you might not receive answers.

!!! note
    `PATCH` is less commonly used and known than `PUT`.

    And many teams use only `PUT`, even for partial updates.

    You are **free** to use them however you want, **FastAPI** doesn't impose any restrictions.

    But this guide shows you, more or less, how they are intended to be used.

### Using Pydantic's `exclude_unset` parameter

!!! warning
    If you are just starting, the tutorial [SQL (Relational) Databases](../tutorial/sql-databases.md){.internal-link target=_blank} that uses SQLAlchemy should be enough.

    Feel free to skip this.

    Peewee is not recommended with FastAPI as it doesn't play well with anything async Python. There are several better alternatives.

!!! info
    These docs assume Pydantic v1.

!!! warning
    These are very technical details about the standards **JSON Schema** and **OpenAPI**.

    If the ideas above already work for you, that might be enough, and you probably don't need these details, feel free to skip them.

Before OpenAPI 3.1.0, OpenAPI used an older and modified version of **JSON Schema**.

JSON Schema didn't have `examples`, so OpenAPI added it's own `example` field to its own modified version.

For this reason it's common to provide them in environment variables that are read by the application.

## Environment Variables

!!! tip
    If you already know what "environment variables" are and how to use them, feel free to skip to the next section below.

Although the hierarchical dependency injection system is very simple to define and use, it's still very powerful.

You can define dependencies that in turn can define dependencies themselves.

In the end, a hierarchical tree of dependencies is built, and the **Dependency Injection** system takes care of solving all these dependencies for you (and their sub-dependencies) and providing (injecting) the results at each step.

    !!! tip
        Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="128-134"
    {!> ../../../docs_src/security/tutorial005.py!}
    ```

## Dependency tree and scopes

Let's review again this dependency tree and the scopes.