because by default, FastAPI will inspect every item inside and make sure it is serializable as JSON, using the same [JSON Compatible Encoder](../tutorial/encoder.md){.internal-link target=_blank} explained in the tutorial. This is what allows you to return **arbitrary objects**, for example database models.

But if you are certain that the content that you are returning is **serializable with JSON**, you can pass it directly to the response class and avoid the extra overhead that FastAPI would...

    * `is_offer` adında opsiyonel bir parametre olup olmadığını ve varsa tipinin `float` olup olmadığını kontol edecek.
    * Bunların hepsi en derin JSON nesnelerinde bile çalışacak.
* Verilerin JSON'a ve JSON'ın python nesnesine dönüşümü otomatik olarak yapılacak.
* Her şeyi OpenAPI ile uyumlu bir şekilde otomatik olarak dokümanlayacak ve bunlarda aşağıdaki gibi kullanılabilecek:
    * Etkileşimli dokümantasyon sistemleri.

* Для запитів `PUT` із `/items/{item_id}`, читає вміст як JSON:
    * Перевірить, чи має обов'язковий атрибут `name` тип `str`.
    * Перевірить, чи має обов'язковий атрибут `price` тип `float`.
    * Перевірить, чи існує необов'язковий атрибут `is_offer` та чи має він тип `bool`.
    * Усе це також працюватиме для глибоко вкладених об'єктів JSON.
* Автоматично конвертує із та в JSON.

<small>* estimation basée sur des tests d'une équipe de développement interne, construisant des applications de production.</small>

## Sponsors

<!-- sponsors -->

* For `PUT` requests to `/items/{item_id}`, Read the body as JSON:
    * Check that it has a required attribute `name` that should be a `str`.
    * Check that it has a required attribute `price` that has to be a `float`.
    * Check that it has an optional attribute `is_offer`, that should be a `bool`, if present.
    * All this would also work for deeply nested JSON objects.
* Convert from and to JSON automatically.

O **JSON Schema** na verdade não tem um campo `example` nos padrões. Versões recentes do JSON Schema definem um campo <a href="https://json-schema.org/draft/2019-09/json-schema-validation.html#rfc.section.9.5" class="external-link" target="_blank">`examples`</a>, mas o OpenAPI 3.0.3 é baseado numa versão mais antiga do JSON Schema que não tinha `examples`.

//
// 	type MyAPIObject struct {
// 		runtime.TypeMeta `json:",inline"`
// 		MyPlugin runtime.Object `json:"myPlugin"`
// 	}
//
// 	type PluginA struct {
// 		AOption string `json:"aOption"`
// 	}
//
// // External package:
//
// 	type MyAPIObject struct {
// 		runtime.TypeMeta `json:",inline"`
// 		MyPlugin runtime.RawExtension `json:"myPlugin"`
// 	}
//
// 	type PluginA struct {

package okhttp3

import kotlinx.serialization.Serializable
import kotlinx.serialization.decodeFromString
import kotlinx.serialization.json.Json

/**
 * A test from the [Web Platform To ASCII](https://github.com/web-platform-tests/wpt/blob/master/url/resources/toascii.json).
 *
 * Each test is a line of the file `toascii.json`.
 */
@Serializable
class WebPlatformToAsciiData {
  var input: String? = null
  var output: String? = null

          @FromJson fun byteStringFromJson(json: String) = json.decodeHex()
        },
      )
      .add(KotlinJsonAdapterFactory())
      .build()
  private val STORY_JSON_ADAPTER = MOSHI.adapter(Story::class.java)

  private val fileSystem = FileSystem.SYSTEM

  private fun readStory(source: BufferedSource): Story {
    return STORY_JSON_ADAPTER.fromJson(source)!!
  }

```JSON
{
  "item": "The Foo Wrestlers"
}
```

Aber wenn der Client `http://example.com/items/bar` anfragt (ein nicht-existierendes `item_id` `"bar"`), erhält er einen HTTP-Statuscode 404 (der „Not Found“-Fehler), und eine JSON-Response wie folgt:

```JSON
{
  "detail": "Item not found"
}
```

!!! tip "Tipp"