# CORS (Cross-Origin Resource Sharing) { #cors-cross-origin-resource-sharing }

<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS" class="external-link" target="_blank">CORS or "Cross-Origin Resource Sharing"</a> refers to the situations when a frontend running in a browser has JavaScript code that communicates with a backend, and the backend is in a different "origin" than the frontend.

## Origin { #origin }

     * Note that this operation is only concerned about determining the coordinates of the transitive dependencies and
     * does not actually resolve the artifact files.
     *
     * @param session the {@link Session}, must not be {@code null}
     * @param root the Maven Dependency, must not be {@code null}

///

## OpenAPI and API docs { #openapi-and-api-docs }

If you return additional status codes and responses directly, they won't be included in the OpenAPI schema (the API docs), because FastAPI doesn't have a way to know beforehand what you are going to return.

# ⚜ (✖️-🇨🇳 ℹ 🤝)

<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS" class="external-link" target="_blank">⚜ ⚖️ "✖️-🇨🇳 ℹ 🤝"</a> 🔗 ⚠ 🕐❔ 🕸 🏃‍♂ 🖥 ✔️ 🕸 📟 👈 🔗 ⏮️ 👩‍💻, &amp; 👩‍💻 🎏 "🇨🇳" 🌘 🕸.

## 🇨🇳

🇨🇳 🌀 🛠️ (`http`, `https`), 🆔 (`myapp.com`, `localhost`, `localhost.tiangolo.com`), &amp; ⛴ (`80`, `443`, `8080`).

, 🌐 👫 🎏 🇨🇳:

* `http://localhost`
* `https://localhost`
* `http://localhost:8080`

Pero FastAPI también soporta el uso de <a href="https://docs.python.org/3/library/dataclasses.html" class="external-link" target="_blank">`dataclasses`</a> de la misma manera:

{* ../../docs_src/dataclasses/tutorial001.py hl[1,7:12,19:20] *}

constraints.NotNull.message = {item} is required.
constraints.Null.message = {item} must be null.
constraints.Past.message = {item} must be a past value.
constraints.Pattern.message = {item} does not match "{regexp}".
constraints.Size.message = The size of {item} must be between {min} and {max}.
# ----------------------------------------------------------
# Hibernate Validator
# -------------------

constraints.NotNull.message = {item} is required.
constraints.Null.message = {item} must be null.
constraints.Past.message = {item} must be a past value.
constraints.Pattern.message = {item} does not match "{regexp}".
constraints.Size.message = The size of {item} must be between {min} and {max}.
# ----------------------------------------------------------
# Hibernate Validator
# -------------------

Ce qui est incroyablement utile au moment de développer et débugger du code qui interagit avec votre API.

///

## Documentation

Et quand vous vous rendez sur <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>, vous verrez la
documentation générée automatiquement et interactive :

<img src="/img/tutorial/path-params/image01.png">

/// info

* Designed around these standards, after a meticulous study. Instead of an afterthought layer on top.
* This also allows using automatic **client code generation** in many languages.

### Automatic docs { #automatic-docs }

Interactive API documentation and exploration web user interfaces. As the framework is based on OpenAPI, there are multiple options, 2 included by default.

* 👉 ⛓ 👈 ⚫️ 🔜 👷 👍 ⭕ 📁 💖 🖼, 📹, ⭕ 💱, ♒️. 🍵 😩 🌐 💾.
* 👆 💪 🤚 🗃 ⚪️➡️ 📂 📁.
* ⚫️ ✔️ <a href="https://docs.python.org/3/glossary.html#term-file-like-object" class="external-link" target="_blank">📁-💖</a> `async` 🔢.
* ⚫️ 🎦 ☑ 🐍 <a href="https://docs.python.org/3/library/tempfile.html#tempfile.SpooledTemporaryFile" class="external-link" target="_blank">`SpooledTemporaryFile`</a> 🎚 👈 👆 💪 🚶‍♀️ 🔗 🎏 🗃 👈 ⌛ 📁-💖 🎚.