This is not a limitation of **FastAPI**, it's part of the HTTP protocol.

///

## Optional File Upload

You can make a file optional by using standard type annotations and setting a default value of `None`:

//// tab | Python 3.10+

```Python hl_lines="9  17"
{!> ../../docs_src/request_files/tutorial001_02_an_py310.py!}

import org.codelibs.fess.helper.PermissionHelper;
import org.codelibs.fess.helper.SystemHelper;
import org.codelibs.fess.util.ComponentUtil;
import org.codelibs.fess.util.RenderDataUtil;
import org.dbflute.optional.OptionalEntity;
import org.dbflute.optional.OptionalThing;
import org.lastaflute.web.Execute;
import org.lastaflute.web.response.HtmlResponse;
import org.lastaflute.web.response.render.RenderData;

import org.codelibs.fess.es.user.exentity.Group;
import org.codelibs.fess.mylasta.direction.FessConfig;
import org.codelibs.fess.util.ComponentUtil;
import org.dbflute.cbean.result.PagingResultBean;
import org.dbflute.optional.OptionalEntity;

import jakarta.annotation.Resource;

public class GroupService {

    @Resource
    protected GroupBhv groupBhv;

    @Resource
    protected FessConfig fessConfig;

    @Resource

import org.codelibs.fess.es.user.exentity.Role;
import org.codelibs.fess.mylasta.direction.FessConfig;
import org.codelibs.fess.util.ComponentUtil;
import org.dbflute.cbean.result.PagingResultBean;
import org.dbflute.optional.OptionalEntity;

import jakarta.annotation.Resource;

public class RoleService {

    @Resource
    protected RoleBhv roleBhv;

    @Resource
    protected FessConfig fessConfig;

    @Resource

import java.util.Locale;

import org.codelibs.core.lang.StringUtil;
import org.codelibs.fess.entity.SearchRequestParams;
import org.codelibs.fess.mylasta.action.FessUserBean;
import org.dbflute.optional.OptionalThing;

public abstract class RankFusionSearcher {
    protected String name;

    public String getName() {
        if (name == null) {

import java.util.Locale;

import org.codelibs.fess.es.config.bsentity.BsCrawlingInfoParam;
import org.codelibs.fess.es.config.exbhv.CrawlingInfoBhv;
import org.codelibs.fess.util.ComponentUtil;
import org.dbflute.optional.OptionalEntity;

/**
 * @author ESFlute (using FreeGen)
 */
public class CrawlingInfoParam extends BsCrawlingInfoParam {

    private static final long serialVersionUID = 1L;

	metricsRouter.Handle(prometheusMetricsV2ResourcePath, auth(metricsResourceHandler()))

	// Metrics v3
	metricsV3Server := newMetricsV3Server(auth)

	// Register metrics v3 handler. It also accepts an optional query
	// parameter `?list` - see handler for details.
	metricsRouter.Methods(http.MethodGet).Path(metricsV3Path + "{pathComps:.*}").Handler(metricsV3Server)

Das ist natürlich nicht optimal und man würde das nicht in der Produktion machen.

In der Produktion hätten Sie eine der oben genannten Optionen.

Aber es ist die einfachste Möglichkeit, sich auf die Serverseite von WebSockets zu konzentrieren und ein funktionierendes Beispiel zu haben:

```Python hl_lines="2  6-38  41-43"
{!../../docs_src/websockets/tutorial001.py!}

import org.gradle.api.Describable
import org.gradle.api.provider.Property
import org.gradle.api.provider.ValueSource
import org.gradle.api.provider.ValueSourceParameters
import org.gradle.api.tasks.Optional
import java.text.SimpleDateFormat
import java.util.Date
import java.util.TimeZone


abstract class BuildTimestampValueSource : ValueSource<String, BuildTimestampValueSource.Parameters>, Describable {

from typing import Optional

import pytest
from dirty_equals import IsDict
from fastapi import APIRouter, Depends, FastAPI
from fastapi.testclient import TestClient

app = FastAPI()

router = APIRouter()


async def common_parameters(q: str, skip: int = 0, limit: int = 100):
    return {"q": q, "skip": skip, "limit": limit}


@app.get("/main-depends/")
async def main_depends(commons: dict = Depends(common_parameters)):