These features are what Marshmallow was built to provide. It is a great library, and I have used it a lot before.

But it was created before there existed Python type hints. So, to define every <abbr title="the definition of how data should be formed">schema</abbr> you need to use specific utils and classes provided by Marshmallow.

/// check | "Inspired **FastAPI** to"

Use code to define "schemas" that provide data types and validation, automatically.

package gorm

import "time"

// Model a basic GoLang struct which includes the following fields: ID, CreatedAt, UpdatedAt, DeletedAt
// It may be embedded into your model or you may build your own model without it
//
//	type User struct {
//	  gorm.Model
//	}
type Model struct {
	ID        uint `gorm:"primarykey"`
	CreatedAt time.Time
	UpdatedAt time.Time
	DeletedAt DeletedAt `gorm:"index"`

 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.app.web.admin.user;

import org.lastaflute.web.validation.Required;
import org.lastaflute.web.validation.theme.conversion.ValidateTypeFailure;

import jakarta.validation.constraints.Size;

/**
 * @author Keiichi Watanabe
 */

        "paths": {
            "/users/me": {
                "get": {
                    "responses": {
                        "200": {
                            "description": "Successful Response",
                            "content": {"application/json": {"schema": {}}},
                        }
                    },
                    "summary": "Read Current User",

 * limitations under the License.
 */

package cmd

import (
	"net/http"
	"strings"
)

// guessIsLoginSTSReq - returns true if incoming request is Login STS user
func guessIsLoginSTSReq(req *http.Request) bool {
	if req == nil {
		return false
	}
	return strings.HasPrefix(req.URL.Path, loginPathPrefix) ||
		(req.Method == http.MethodPost && req.URL.Path == SlashSeparator &&

from fastapi import FastAPI, Header
from typing_extensions import Annotated

app = FastAPI()


@app.get("/items/")
async def read_items(user_agent: Annotated[Union[str, None], Header()] = None):

from typing import Union

from fastapi import FastAPI, Header

app = FastAPI()


@app.get("/items/")
async def read_items(user_agent: Union[str, None] = Header(default=None)):

        "paths": {
            "/users/{user_id}": {
                "get": {
                    "summary": "Read Users",
                    "operationId": "read_users_users__user_id__get",
                    "parameters": [
                        {
                            "required": True,
                            "schema": {"title": "User Id", "type": "integer"},

        "paths": {
            "/users/me": {
                "get": {
                    "responses": {
                        "200": {
                            "description": "Successful Response",
                            "content": {"application/json": {"schema": {}}},
                        }
                    },
                    "summary": "Read Current User",

        "paths": {
            "/users/me": {
                "get": {
                    "responses": {
                        "200": {
                            "description": "Successful Response",
                            "content": {"application/json": {"schema": {}}},
                        }
                    },
                    "summary": "Read Current User",