Wenn Sie keinen spezifischen Wert haben wollen, sondern der Parameter einfach optional sein soll, dann setzen Sie den Defaultwert auf `None`.

Aber wenn Sie wollen, dass ein Query-Parameter erforderlich ist, vergeben Sie einfach keinen Defaultwert:

{* ../../docs_src/query_params/tutorial005_py39.py hl[6:7] *}

Hier ist `needy` ein erforderlicher Query-Parameter vom Typ `str`.

Wenn Sie in Ihrem Browser eine URL wie:

```

Die Geschichte von **FastAPI** ist zu einem großen Teil die Geschichte seiner Vorgänger.

Wie im Abschnitt [Alternativen](alternatives.md){.internal-link target=_blank} gesagt:

<blockquote markdown="1">

**FastAPI** würde ohne die frühere Arbeit anderer nicht existieren.

Es wurden zuvor viele Tools entwickelt, die als Inspiration für seine Entwicklung dienten.

plugins {
    `kotlin-dsl`
}

description = "Provides a plugin to define the version and name for subproject publications"

group = "gradlebuild"

dependencies {
    api(platform(projects.buildPlatform))

    implementation(projects.basics)

    implementation("com.google.code.gson:gson")

{* ../../docs_src/query_params_str_validations/tutorial003_an_py310.py hl[10] *}

## Add regular expressions { #add-regular-expressions }

You can define a <abbr title="A regular expression, regex or regexp is a sequence of characters that define a search pattern for strings.">regular expression</abbr> `pattern` that the parameter should match:

{* ../../docs_src/query_params_str_validations/tutorial004_an_py310.py hl[11] *}

# Define this here and not in the main mkdocs.yml file because that one is auto
# updated and written, and the script would remove the env var
markdown_extensions:
  pymdownx.highlight:

**FastAPI** will **extract** the data for **each field** from the **cookies** received in the request and give you the Pydantic model you defined.

## Check the Docs { #check-the-docs }

You can see the defined cookies in the docs UI at `/docs`:

<div class="screenshot">
<img src="/img/tutorial/cookie-param-models/image01.png">
</div>

/// info

## Eine **FastAPI**-Anwendung mounten { #mounting-a-fastapi-application }

# EditorConfig helps developers define and maintain consistent
# coding styles between different editors and IDEs
# editorconfig.org

root = true

[*]

indent_style = space
indent_size = 4

end_of_line = lf
charset = utf-8
trim_trailing_whitespace = true
insert_final_newline = true

spelling_languages = en-US

# Markdown files sometimes need trailing whitespaces.
[*.md]
trim_trailing_whitespace = false

import static org.junit.jupiter.api.Assertions.assertNotNull;

import org.junit.jupiter.api.Test;

/**
 * Tests for the {@link ResolverType} enum.
 * This class ensures that the enum constants are defined as expected.
 */
class ResolverTypeTest {

    /**
     * Tests that all expected enum constants exist.
     */
    @Test
    void testEnumConstants() {

     * @param settings the suggest settings to apply
     * @param index the name of the index from which documents will be deleted
     * @param queryBuilder the query that defines which documents to delete
     * @return a result object containing information about the delete operation
     */