* Each tag configuration follows the pattern: tagname[attr=value].classname#id
     *
     * Examples:
     * - "div.content" matches div elements with class "content"
     * - "span#header" matches span elements with ID "header"
     * - "p[data-type=ad]" matches p elements with data-type attribute equal to "ad"
     *
     * @param value the comma-separated string of pruned tag configurations

# Sub-dependencies { #sub-dependencies }

You can create dependencies that have **sub-dependencies**.

They can be as **deep** as you need them to be.

**FastAPI** will take care of solving them.

## First dependency "dependable" { #first-dependency-dependable }

You could create a first dependency ("dependable") like:

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[8:9] *}

# Middleware { #middleware }

You can add middleware to **FastAPI** applications.

A "middleware" is a function that works with every **request** before it is processed by any specific *path operation*. And also with every **response** before returning it.

* It takes each **request** that comes to your application.
* It can then do something to that **request** or run any needed code.

folder using the session. The server side applications need not create a presigned URL and serve to the client for each file. Since, the client would have the session it can do it by itself.

The temporary security credentials returned by this API consists of an access key, a secret key, and a security token. Applications can use these temporary security credentials to sign calls to MinIO API operations. The policy applied to these temporary credentials is inherited from the MinIO user credentials....

But you can return a `JSONResponse` directly from your *path operations*.

It might be useful, for example, to return custom headers or cookies.

## Return a `Response` { #return-a-response }

In fact, you can return any `Response` or any sub-class of it.

/// tip

`JSONResponse` itself is a sub-class of `Response`.

///

For those cases, you can use a `Response` parameter.

## Use a `Response` parameter { #use-a-response-parameter }

You can declare a parameter of type `Response` in your *path operation function* (as you can do for cookies and headers).

And then you can set the `status_code` in that *temporal* response object.

    /**
     * Determines the address of a host given it's host name. The name can be a NetBIOS name like
     * "freto" or an IP address like "192.168.1.15". It cannot be a DNS name;
     * the analygous {@link jcifs.netbios.UniAddress} or {@link java.net.InetAddress}
     * <code>getByName</code> methods can be used for that.
     *
     * @param host
     *            hostname to resolve

When defining WebSockets, you normally declare a parameter of type `WebSocket` and with it you can read data from the client and send data to it.

It is provided directly by Starlette, but you can import it from `fastapi`:

```python
from fastapi import WebSocket
```

/// tip

}
```

## Recap { #recap }

You can add multiple body parameters to your *path operation function*, even though a request can only have a single body.

But **FastAPI** will handle it, give you the correct data in your function, and validate and document the correct schema in the *path operation*.

You can also declare singular values to be received as part of the body.

# Body - Fields { #body-fields }

The same way you can declare additional validation and metadata in *path operation function* parameters with `Query`, `Path` and `Body`, you can declare validation and metadata inside of Pydantic models using Pydantic's `Field`.

## Import `Field` { #import-field }

First, you have to import it:

{* ../../docs_src/body_fields/tutorial001_an_py310.py hl[4] *}


/// warning