# Những bước đầu tiên

Tệp tin FastAPI đơn giản nhất có thể trông như này:

```Python
{!../../docs_src/first_steps/tutorial001.py!}
```

Sao chép sang một tệp tin `main.py`.

Chạy live server:

<div class="termy">

```console
$ uvicorn main:app --reload

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)

```Python hl_lines="1  15"
{!../../docs_src/debugging/tutorial001.py!}
```

### About `__name__ == "__main__"`

The main purpose of the `__name__ == "__main__"` is to have some code that is executed when your file is called with:

<div class="termy">

```console
$ python myapp.py
```

</div>

but is not called when another file imports it, like in:

```Python

```Python hl_lines="3-16  18"
{!../../docs_src/metadata/tutorial004.py!}
```

👀 👈 👆 💪 ⚙️ ✍ 🔘 📛, 🖼 "💳" 🔜 🎦 🦁 (**💳**) & "🎀" 🔜 🎦 ❕ (_🎀_).

/// tip

👆 🚫 ✔️ 🚮 🗃 🌐 🔖 👈 👆 ⚙️.

///

### ⚙️ 👆 🔖

⚙️ `tags` 🔢 ⏮️ 👆 *➡ 🛠️* (& `APIRouter`Ⓜ) 🛠️ 👫 🎏 🔖:

```Python hl_lines="21  26"
{!../../docs_src/metadata/tutorial004.py!}
```

/// info

```Python hl_lines="1  4  7-9"
{!../../docs_src/extending_openapi/tutorial001.py!}
```

### Gerar o esquema OpenAPI

Em seguida, use a mesma função utilitária para gerar o esquema OpenAPI, dentro de uma função `custom_openapi()`:

```Python hl_lines="2  15-21"
{!../../docs_src/extending_openapi/tutorial001.py!}
```

### Modificar o esquema OpenAPI

//// tab | Python 3.10+

```Python hl_lines="7"
{!> ../../docs_src/query_params/tutorial002_py310.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="9"
{!> ../../docs_src/query_params/tutorial002.py!}
```

////

В этом случае, параметр  `q` будет не обязательным и будет иметь значение `None` по умолчанию.

/// check | "Важно"

```Python hl_lines="4"
{!> ../../docs_src/body_fields/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="4"
{!> ../../docs_src/body_fields/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="4"
{!> ../../docs_src/body_fields/tutorial001_an.py!}
```

////

//// tab | Python 3.10+ Annotated가 없는 경우

/// tip | "팁"

```Python hl_lines="1"
{!> ../../docs_src/python_types/tutorial009_py310.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="1  4"
{!> ../../docs_src/python_types/tutorial009.py!}
```

////

//// tab | Python 3.8+ alternative

```Python hl_lines="1  4"
{!> ../../docs_src/python_types/tutorial009b.py!}
```

////

#### Using `Union` or `Optional`

```Python hl_lines="3  6-8"
{!../../docs_src/sub_applications/tutorial001.py!}
```

### Unteranwendung

Erstellen Sie dann Ihre Unteranwendung und deren *Pfadoperationen*.

Diese Unteranwendung ist nur eine weitere Standard-FastAPI-Anwendung, aber diese wird „gemountet“:

```Python hl_lines="11  14-16"
{!../../docs_src/sub_applications/tutorial001.py!}
```

### Die Unteranwendung mounten

{!../../docs_src/path_operation_advanced_configuration/tutorial001.py!}
```

### 使用 *路径操作函数* 的函数名作为 operationId

如果你想用你的 API 的函数名作为 `operationId` 的名字，你可以遍历一遍 API 的函数名，然后使用他们的 `APIRoute.name` 重写每个 *路径操作* 的 `operation_id`。

你应该在添加了所有 *路径操作* 之后执行此操作。

```Python hl_lines="2 12 13 14 15 16 17 18 19 20 21 24"
{!../../docs_src/path_operation_advanced_configuration/tutorial002.py!}
```

/// tip

{!> ../../docs_src/query_params_str_validations/tutorial003_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="10"
{!> ../../docs_src/query_params_str_validations/tutorial003_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="11"
{!> ../../docs_src/query_params_str_validations/tutorial003_an.py!}
```

////

//// tab | Python 3.10+ без Annotated