///

## Datenvalidierung { #data-validation }

Wenn Sie aber im Browser <a href="http://127.0.0.1:8000/items/foo" class="external-link" target="_blank">http://127.0.0.1:8000/items/foo</a> besuchen, erhalten Sie eine hübsche HTTP-Fehlermeldung:

```JSON
{

import org.junit.Test;

/**
 * Test class for resource loading functionality in Suggester class.
 *
 * Tests cover:
 * - Successful resource loading
 * - Missing resource error handling
 * - Resource content validation
 * - InputStream null safety in try-with-resources
 */
public class SuggesterResourceLoadingTest {

    /**
     * Test that getDefaultMappings correctly loads and returns mapping resource.
     */
    @Test

///

```Python
commons: CommonQueryParams ...
```

////

...doesn't have any special meaning for **FastAPI**. FastAPI won't use it for data conversion, validation, etc. (as it is using the `Depends(CommonQueryParams)` for that).

You could actually write just:

//// tab | Python 3.9+

```Python
commons: Annotated[Any, Depends(CommonQueryParams)]
```

Entonces, con esa declaración de tipo, **FastAPI** te ofrece <abbr title="convertir el string que viene de un request HTTP en datos de Python">"parsing"</abbr> automático de request.

///

## Validación de datos { #data-validation }

Pero si vas al navegador en <a href="http://127.0.0.1:8000/items/foo" class="external-link" target="_blank">http://127.0.0.1:8000/items/foo</a>, verás un bonito error HTTP de:

```JSON
{
  "detail": [

                    "schema": {
                        "$ref": "#/components/schemas/Item"
                    }
                }
            }
        },
        "422": {
            "description": "Validation Error",
            "content": {
                "application/json": {
                    "schema": {
                        "$ref": "#/components/schemas/HTTPValidationError"
                    }
                }

                    "schema": {
                        "$ref": "#/components/schemas/Item"
                    }
                }
            }
        },
        "422": {
            "description": "Validation Error",
            "content": {
                "application/json": {
                    "schema": {
                        "$ref": "#/components/schemas/HTTPValidationError"
                    }
                }

                    "schema": {
                        "$ref": "#/components/schemas/Item"
                    }
                }
            }
        },
        "422": {
            "description": "Validation Error",
            "content": {
                "application/json": {
                    "schema": {
                        "$ref": "#/components/schemas/HTTPValidationError"
                    }
                }

* Поддержку редактора кода (автозавершение и т.д.), даже для вложенных моделей
* Преобразование данных
* Валидацию данных
* Автоматическую документацию

## Особые типы и валидация { #special-types-and-validation }

Помимо обычных простых типов, таких как `str`, `int`, `float` и т.д., вы можете использовать более сложные простые типы, которые наследуются от `str`.

            ],
            "msg": "value is not a valid integer",
            "type": "type_error.integer"
        }
    ]
}
```

Ви отримаєте текстову версію:

```
1 validation error
path -> item_id
  value is not a valid integer (type=type_error.integer)
```

#### `RequestValidationError` проти `ValidationError`

/// warning | Увага

And you could do this even if the data type in the request is not JSON.

For example, in this application we don't use FastAPI's integrated functionality to extract the JSON Schema from Pydantic models nor the automatic validation for JSON. In fact, we are declaring the request content type as YAML, not JSON:

{* ../../docs_src/path_operation_advanced_configuration/tutorial007_py39.py hl[15:20, 22] *}