/// tip

যখন আপনি `Optional` বা `Union[Something, None]` ব্যবহার করেন এবং কোনো ডিফল্ট মান না থাকে, Pydantic-এর একটি বিশেষ আচরণ রয়েছে, আপনি Pydantic ডকুমেন্টেশনে [Required Optional fields](https://docs.pydantic.dev/latest/concepts/models/#required-optional-fields) সম্পর্কে আরও পড়তে পারেন।

///

## মেটাডাটা অ্যানোটেশন সহ টাইপ হিন্টস

Python-এ এমন একটি ফিচার আছে যা `Annotated` ব্যবহার করে এই টাইপ হিন্টগুলিতে **অতিরিক্ত মেটাডাটা** রাখতে দেয়।

///

/// tip | Consejo

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 ╭────────── FastAPI CLI - Development mode ───────────╮
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 │  Serving at: http://127.0.0.1:8000                  │
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 │  Running in development mode, for production use:   │

Juste du **Python** standard.

Par exemple, pour un `int`:

```Python
item_id: int
```

ou pour un modèle `Item` plus complexe :

```Python
item: Item
```

... et avec cette déclaration unique, vous obtenez :

* Une assistance dans votre IDE, notamment :
    * la complétion.

Hepsi sadece **Python** standartlarına dayalıdır.

Örnek olarak, `int` tanımlamak için:

```Python
item_id: int
```

ya da daha kompleks herhangi bir python modelini tanımlayabiliriz, örneğin `Item` modeli için:

```Python
item: Item
```

...ve sadece kısa bir parametre tipi belirterek elde ettiklerimiz:

* Editör desteğiyle birlikte:
    * Otomatik tamamlama.
    * Tip kontrolü.

/// tip

Pydantic heeft een speciaal gedrag wanneer je `Optional` of `Union[EenType, None]` gebruikt zonder een standaardwaarde, je kunt er meer over lezen in de Pydantic-documentatie over <a href="https://docs.pydantic.dev/2.3/usage/models/#required-fields" class="external-link" target="_blank">Verplichte optionele velden</a>.

///

## Type Hints met Metadata Annotaties

Timing (DIT) modes in the [`crypto/subtle`](/pkg/crypto/subtle) package. This
mode can be enabled for an entire program with the `dataindependenttiming` setting.
For Go 1.24 it defaults to `dataindependenttiming=0`. There is no change in default
behavior from Go 1.23 when `dataindependenttiming` is unset.
Using `dataindependenttiming=1` enables the DIT mode for the entire Go program.

 *   <li>ftpConfigServerTimeZoneId: The time zone ID of the FTP server.</li>
 *   <li>activeExternalHost: The external IP address to use for active mode FTP.</li>
 *   <li>activeMinPort: The minimum port number for active mode FTP.</li>
 *   <li>activeMaxPort: The maximum port number for active mode FTP.</li>
 *   <li>autodetectEncoding: Whether to automatically detect UTF-8 encoding.</li>

/// check | **FastAPI** usa isso para

Controlar toda a validação de dados, serialização de dados e modelo de documentação automática (baseado no JSON Schema).

**FastAPI** então pega dados do JSON Schema e coloca eles no OpenAPI, à parte de todas as outras coisas que ele faz.

///