///

In HTTP, you send a numeric status code of 3 digits as part of the response.

These status codes have a name associated to recognize them, but the important part is the number.

In short:

* `100 - 199` are for "Information". You rarely use them directly.  Responses with these status codes cannot have a body.
* **`200 - 299`** are for "Successful" responses. These are the ones you would use the most.

FastAPI includes some default configuration parameters appropriate for most of the use cases.

It includes these default configurations:

{* ../../fastapi/openapi/docs.py ln[9:24] hl[18:24] *}

You can override any of them by setting a different value in the argument `swagger_ui_parameters`.

For example, to disable `deepLinking` you could pass these settings to `swagger_ui_parameters`:

{* ../../docs_src/configure_swagger_ui/tutorial003_py39.py hl[3] *}

These types that have internal types are called "**generic**" types. And it's possible to declare them, even with their internal types.

To declare those types and the internal types, you can use the standard Python module `typing`. It exists specifically to support these type hints.

#### Newer versions of Python { #newer-versions-of-python }

### List of English terms and their preferred French translations

Below is a list of English terms and their preferred French translations, separated by a colon («:»). Use these translations, do not use your own. If an existing translation does not use these terms, update it to use them.

* «/// note | Technical Details»: «/// note | Détails techniques»
* «/// note»: «/// note | Remarque»
* «/// tip»: «/// tip | Astuce»

This section highlights **venture-backed** and **company-supported** solutions from companies that sponsor FastAPI. These products provide **additional features** and **integrations** on top of high-quality generated SDKs.

By ✨ [**sponsoring FastAPI**](../help-fastapi.md#sponsor-the-author){.internal-link target=_blank} ✨, these companies help ensure the framework and its **ecosystem** remain healthy and **sustainable**.

# Path Operation Configuration { #path-operation-configuration }

There are several parameters that you can pass to your *path operation decorator* to configure it.

/// warning

Notice that these parameters are passed directly to the *path operation decorator*, not to your *path operation function*.

///

## Response Status Code { #response-status-code }

You can define the (HTTP) `status_code` to be used in the response of your *path operation*.

This practice is common enough that it has a name, these environment variables are commonly placed in a file `.env`, and the file is called a "dotenv".

/// tip

A file starting with a dot (`.`) is a hidden file in Unix-like systems, like Linux and macOS.

But a dotenv file doesn't really have to have that exact filename.

///

/// tip

If you are already using **FastAPI** version **0.99.0 or above**, you can probably **skip** these details.

They are more relevant for older versions, before OpenAPI 3.1.0 was available.

You can consider this a brief OpenAPI and JSON Schema **history lesson**. 🤓

///

/// warning

These are very technical details about the standards **JSON Schema** and **OpenAPI**.

## Override the default exception handlers { #override-the-default-exception-handlers }

**FastAPI** has some default exception handlers.

These handlers are in charge of returning the default JSON responses when you `raise` an `HTTPException` and when the request has invalid data.

You can override these exception handlers with your own.

### Override request validation exceptions { #override-request-validation-exceptions }

These headers preserve information about the original request that would otherwise be lost:

* **X-Forwarded-For**: The original client's IP address
* **X-Forwarded-Proto**: The original protocol (`https`)
* **X-Forwarded-Host**: The original host (`mysuperapp.com`)