```

In this case, `item_id` is declared to be an `int`.

!!! check
    This will give you editor support inside of your function, with error checks, completion, etc.

## Data <abbr title="also known as: serialization, parsing, marshalling">conversion</abbr>

* Configure any required permissions and roles using dependencies.
* Never store plaintext passwords, only password hashes.
* Implement and use well-known cryptographic tools, like Passlib and JWT tokens, etc.
* Add more granular permission controls with OAuth2 scopes where needed.
* ...etc.

* 🐍 <a href="https://github.com/tiangolo/fastapi" class="external-link" target="_blank">**FastAPI**</a> 👩‍💻:
    * **⏩**: 📶 ↕ 🎭, 🔛 🇷🇪 ⏮️ **✳** &amp; **🚶** (👏 💃 &amp; Pydantic).
    * **🏋️**: 👑 👨‍🎨 🐕‍🦺. <abbr title="also known as auto-complete, autocompletion, IntelliSense">🛠️</abbr> 🌐. 🌘 🕰 🛠️.
    * **⏩**: 🔧 ⏩ ⚙️ &amp; 💡. 🌘 🕰 👂 🩺.
    * **📏**: 📉 📟 ❎. 💗 ⚒ ⚪️➡️ 🔠 🔢 📄.
    * **🏋️**: 🤚 🏭-🔜 📟. ⏮️ 🏧 🎓 🧾.

"docs_src/dependencies/tutorial008b.py" = ["B904"]
"docs_src/dependencies/tutorial008b_an.py" = ["B904"]
"docs_src/dependencies/tutorial008b_an_py39.py" = ["B904"]


[tool.ruff.lint.isort]
known-third-party = ["fastapi", "pydantic", "starlette"]

[tool.ruff.lint.pyupgrade]
# Preserve types, even if a file imports `from __future__ import annotations`.

* <a href="https://github.com/OAI/OpenAPI-Specification" class="external-link" target="_blank"><strong>OpenAPI</strong></a> for API creation, including declarations of <abbr title="also known as: endpoints, routes">path</abbr> <abbr title="also known as HTTP methods, as POST, GET, PUT, DELETE">operations</abbr>, parameters, body requests, security, etc.

**FastAPI** 🤝 👆 📄:

### ⚓️ 🔛 📂 🐩

* <a href="https://github.com/OAI/OpenAPI-Specification" class="external-link" target="_blank"><strong>🗄</strong></a> 🛠️ 🏗, ✅ 📄 <abbr title="also known as: endpoints, routes">➡</abbr> <abbr title="also known as HTTP methods, as POST, GET, PUT, DELETE">🛠️</abbr>, 🔢, 💪 📨, 💂‍♂, ♒️.
* 🏧 📊 🏷 🧾 ⏮️ <a href="https://json-schema.org/" class="external-link" target="_blank"><strong>🎻 🔗</strong></a> (🗄 ⚫️ 🧢 🔛 🎻 🔗).

# 🔗

**FastAPI** ✔️ 📶 🏋️ ✋️ 🏋️ **<abbr title="also known as components, resources, providers, services, injectables">🔗 💉</abbr>** ⚙️.

⚫️ 🏗 📶 🙅 ⚙️, &amp; ⚒ ⚫️ 📶 ⏩ 🙆 👩‍💻 🛠️ 🎏 🦲 ⏮️ **FastAPI**.

## ⚫️❔ "🔗 💉"

**"🔗 💉"** ⛓, 📋, 👈 📤 🌌 👆 📟 (👉 💼, 👆 *➡ 🛠️ 🔢*) 📣 👜 👈 ⚫️ 🚚 👷 &amp; ⚙️: "🔗".

&amp; ⤴️, 👈 ⚙️ (👉 💼 **FastAPI**) 🔜 ✊ 💅 🔨 ⚫️❔ 💪 🚚 👆 📟 ⏮️ 📚 💪 🔗 ("💉" 🔗).

👉 📶 ⚠ 🕐❔ 👆 💪:

But a variable like `user-agent` is invalid in Python.

So, by default, `Header` will convert the parameter names characters from underscore (`_`) to hyphen (`-`) to extract and document the headers.

Also, HTTP headers are case-insensitive, so, you can declare them with standard Python style (also known as "snake_case").

Pass `*`, as the first parameter of the function.

Python won't do anything with that `*`, but it will know that all the following parameters should be called as keyword arguments (key-value pairs), also known as <abbr title="From: K-ey W-ord Arg-uments"><code>kwargs</code></abbr>. Even if they don't have a default value.

```Python hl_lines="7"
{!../../../docs_src/path_params_numeric_validations/tutorial003.py!}
```

```Python hl_lines="7"
{!../../../docs_src/path_params/tutorial002.py!}
```

👉 💼, `item_id` 📣 `int`.

!!! check
    👉 🔜 🤝 👆 👨‍🎨 🐕‍🦺 🔘 👆 🔢, ⏮️ ❌ ✅, 🛠️, ♒️.

## 💽 <abbr title="also known as: serialization, parsing, marshalling">🛠️</abbr>

🚥 👆 🏃 👉 🖼 &amp; 📂 👆 🖥 <a href="http://127.0.0.1:8000/items/3" class="external-link" target="_blank">http://127.0.0.1:8000/items/3</a>, 👆 🔜 👀 📨:

```JSON