///

/// tip

If you need to do any type of validation that requires communicating with any **external component**, like a database or another API, you should instead use **FastAPI Dependencies**, you will learn about them later.

These custom validators are for things that can be checked with **only** the **same data** provided in the request.

///

### Understand that Code { #understand-that-code }

---

"_If you're looking to learn one **modern framework** for building REST APIs, check out **FastAPI** [...] It's fast, easy to use and easy to learn [...]_"

"_We've switched over to **FastAPI** for our **APIs** [...] I think you'll like it [...]_"

**FastAPI** provides several tools to help you deal with **Security** easily, rapidly, in a standard way, without having to study and learn all the security specifications.

But first, let's check some small concepts.

## In a hurry? { #in-a-hurry }

[guava.dev/api](https://guava.dev/api). You can also jump right to a specific
class by appending the class name to guava.dev. For example,
[guava.dev/ImmutableList](https://guava.dev/ImmutableList)!

## Learn about Guava

-   Our users' guide, [Guava Explained]
-   [A nice collection](https://www.tfnico.com/presentations/google-guava) of
    other helpful links

## Links

</blockquote>

## Investigation { #investigation }

By using all the previous alternatives I had the chance to learn from all of them, take ideas, and combine them in the best way I could find for myself and the teams of developers I have worked with.

For example, it was clear that ideally it should be based on standard Python type hints.

/// tip

You can learn more about it in the [deployment documentation](deployment/index.md){.internal-link target=_blank}.

# Install Visual Studio 2022 Build Tools + Compiler
SHELL ["cmd", "/S", "/C"]
# Packages, and component versions, can be found here:
# https://learn.microsoft.com/en-us/visualstudio/install/workload-component-id-vs-build-tools
RUN C:\TEMP\vs_community.exe \
        --quiet --wait --norestart --nocache \
        --add Microsoft.VisualStudio.Component.VC.Tools.x86.x64 \

---

"_If you're looking to learn one **modern framework** for building REST APIs, check out **FastAPI** [...] It's fast, easy to use and easy to learn [...]_"

"_We've switched over to **FastAPI** for our **APIs** [...] I think you'll like it [...]_"

That means that **any value** read in Python from an environment variable **will be a `str`**, and any conversion to a different type or any validation has to be done in code.

You will learn more about using environment variables for handling **application settings** in the [Advanced User Guide - Settings and Environment Variables](./advanced/settings.md){.internal-link target=_blank}.

///

## More info { #more-info }

To learn more about the options, check Starlette's documentation for:

* <a href="https://www.starlette.io/websockets/" class="external-link" target="_blank">The `WebSocket` class</a>.