* The *path* can contain an <a href="https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.1.0.md#key-expression" class="external-link" target="_blank">OpenAPI 3 expression</a> (see more below) where it can use variables with parameters and parts of the original request sent to *your API*.

### A expressão do caminho do callback

Bu <abbr title="Spesifikasyon: Specification">spesifikasyon</abbr> form alanlarını adlandırırken isimlerinin birebir `username` ve `password` olmasını ve JSON verisi yerine form verisi olarak gönderilmesini gerektirir.

### La expresión del path del callback

/// warning

Extra keys passed to `Field` will also be present in the resulting OpenAPI schema for your application.
As these keys may not necessarily be part of the OpenAPI specification, some OpenAPI tools, for example [the OpenAPI validator](https://validator.swagger.io/), may not work with your generated schema.

///

## Recap { #recap }

* <a href="https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.1.0.md#parameter-object" class="external-link" target="_blank">`Parameter Object` (в специфікації)</a> використовується FastAPI для:
    * `Path()`
    * `Query()`
    * `Header()`
    * `Cookie()`

// constant. See the Go language specification's "Length and capacity" section for
// details.
func cap(v Type) int

// The make built-in function allocates and initializes an object of type
// slice, map, or chan (only). Like new, the first argument is a type, not a
// value. Unlike new, make's return type is the same as the type of its
// argument, not a pointer to it. The specification of the result depends on
// the type:
//

#### API "schema" { #api-schema }

In this case, <a href="https://github.com/OAI/OpenAPI-Specification" class="external-link" target="_blank">OpenAPI</a> is a specification that dictates how to define a schema of your API.

This schema definition includes your API paths, the possible parameters they take, etc.

#### Data "schema" { #data-schema }

### Technical Details: `root_path` { #technical-details-root-path }

When you mount a sub-application as described above, FastAPI will take care of communicating the mount path for the sub-application using a mechanism from the ASGI specification called a `root_path`.

That way, the sub-application will know to use that path prefix for the docs UI.

そのため、OpenAPIでは同じ目的のために<a href="https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.3.md#fixed-fields-20" class="external-link" target="_blank">`example`</a>を独自に定義しており（`examples`ではなく`example`として）、それがdocs UI（Swagger UIを使用）で使用されています。