from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: str | None = Query(
        default=None,
        title="Query string",
        description="Query string for the items to search in the database that have a good match",
        min_length=3,
    ),
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q})

def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {},

def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/users/me": {
                "get": {
                    "responses": {
                        "200": {

Vous pouvez aussi rajouter un second paramètre `min_length` :

{* ../../docs_src/query_params_str_validations/tutorial003.py hl[9] *}

## Ajouter des validations par expressions régulières

On peut définir une <abbr title="Une expression régulière, regex ou regexp est une suite de caractères qui définit un pattern de correspondance pour les chaînes de caractères.">expression régulière</abbr> à laquelle le paramètre doit correspondre :

from typing import Union

from fastapi import FastAPI, Query

app = FastAPI()


@app.get("/items/")
async def read_items(
    q: Union[str, None] = Query(
        default=None,
        title="Query string",
        description="Query string for the items to search in the database that have a good match",
        min_length=3,
    ),
):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:

def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {
            "title": "FastAPI",
            "version": "0.1.0",
        },
        "paths": {},

def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/users/me": {
                "get": {
                    "responses": {
                        "200": {

        Please open Gradle Native-related issues on [the Gradle Native repository](https://github.com/gradle/gradle-native/issues)

        Provide a brief summary of the issue in the title above
  - type: textarea
    id: expected-behavior
    attributes:
      label: Expected Behavior
      description: Tell us how it should work
    validations:
      required: true
  - type: textarea

<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="referrer" content="no-referrer">
<title>${f:h(displayQuery)}-<la:message
		key="labels.search_title" /></title>
<c:if test="${osddLink}">
	<link rel="search" type="application/opensearchdescription+xml"
		href="${fe:url('/osdd')}"
		title="<la:message key="labels.index_osdd_title" />" />
</c:if>
<link href="${fe:url('/css/bootstrap.min.css')}" rel="stylesheet"

<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="referrer" content="no-referrer">
<title>${f:h(displayQuery)}-<la:message
		key="labels.search_title" /></title>
<c:if test="${osddLink}">
	<link rel="search" type="application/opensearchdescription+xml"
		href="${fe:url('/osdd')}"
		title="<la:message key="labels.index_osdd_title" />" />
</c:if>
<link href="${fe:url('/css/bootstrap.min.css')}" rel="stylesheet"