Por padrão, o **FastAPI** irá converter automaticamente o valor do retorno para JSON utilizando o `jsonable_encoder` explicado em [JSON Compatible Encoder](../tutorial/encoder.md){.internal-link target=_blank}.

Então, por baixo dos panos, ele incluiria esses dados compatíveis com JSON (e.g. um `dict`) dentro de uma `JSONResponse` que é utilizada para enviar uma resposta para o cliente.

package main

import (
	"encoding/json"
	"errors"
	"fmt"
	"log"
	"net/http"
)

func writeErrorResponse(w http.ResponseWriter, err error) {
	w.WriteHeader(http.StatusBadRequest)
	json.NewEncoder(w).Encode(map[string]string{
		"reason": fmt.Sprintf("%v", err),
	})
}

type Resp struct {
	User               string                 `json:"user"`
	MaxValiditySeconds int                    `json:"maxValiditySeconds"`

    /**
     * @throws Exception
     */
    public void testEncode() throws Exception {
        assertEquals("1", ENCODED_DATA, Base64Util.encode(BINARY_DATA));
        System.out.println(Base64Util.encode(new byte[] { 'a', 'b', 'c' }));
    }

    /**
     * @throws Exception
     */
    public void testDecode() throws Exception {

from datetime import datetime
from typing import Union

from fastapi import FastAPI
from fastapi.encoders import jsonable_encoder
from fastapi.responses import JSONResponse
from pydantic import BaseModel


class Item(BaseModel):
    title: str
    timestamp: datetime
    description: Union[str, None] = None


app = FastAPI()


@app.put("/items/{id}")
def update_item(id: str, item: Item):

  /**
   * Returns an {@link Escaper} instance that escapes strings so they can be safely included in <a
   * href="https://url.spec.whatwg.org/#application-x-www-form-urlencoded-percent-encode-set">URL
   * form parameter names and values</a>. Escaping is performed with the UTF-8 character encoding.
   * The caller is responsible for <a

    /**
     * 
     * @param flags
     */
    public AvFlags ( int flags ) {
        this(encode(flags));
    }


    /**
     * 
     * @return flags
     */
    public int getFlags () {
        return SMBUtil.readInt4(this.getRaw(), 0);
    }


    private static byte[] encode ( int flags ) {
        byte[] raw = new byte[4];
        SMBUtil.writeInt4(flags, raw, 0);
        return raw;

from typing import List, Union

from fastapi import FastAPI
from fastapi.encoders import jsonable_encoder
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: Union[str, None] = None
    description: Union[str, None] = None
    price: Union[float, None] = None
    tax: float = 10.5
    tags: List[str] = []


items = {
    "foo": {"name": "Foo", "price": 50.2},

from fastapi import FastAPI
from fastapi.encoders import jsonable_encoder
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str | None = None
    description: str | None = None
    price: float | None = None
    tax: float = 10.5
    tags: list[str] = []


items = {
    "foo": {"name": "Foo", "price": 50.2},
    "bar": {"name": "Bar", "description": "The bartenders", "price": 62, "tax": 20.2},

):
    current_username_bytes = credentials.username.encode("utf8")
    correct_username_bytes = b"stanleyjobson"
    is_correct_username = secrets.compare_digest(
        current_username_bytes, correct_username_bytes
    )
    current_password_bytes = credentials.password.encode("utf8")
    correct_password_bytes = b"swordfish"
    is_correct_password = secrets.compare_digest(

from fastapi import FastAPI, Request, status
from fastapi.encoders import jsonable_encoder
from fastapi.exceptions import RequestValidationError
from fastapi.responses import JSONResponse
from pydantic import BaseModel

app = FastAPI()


@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request: Request, exc: RequestValidationError):
    return JSONResponse(
        status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,