Another big feature needed by APIs is data validation, making sure that the data is valid, given certain parameters. For example, that some field is an `int`, and not some random string. This is especially useful for incoming data.

Without a data validation system, you would have to do all the checks by hand, in code.

## Handle JWT tokens

Import the modules installed.

Create a random secret key that will be used to sign the JWT tokens.

To generate a secure random secret key use the command:

<div class="termy">

```console
$ openssl rand -hex 32

09d25e094faa6ca2556c818166b7a9563b93f7099f6f0f4caa6cf63b88e8d3e7
```

    assert (
        "oauth2RedirectUrl: window.location.origin + '/docs/oauth2-redirect'"
        in response.text
    )


def test_swagger_ui_oauth2_redirect():
    response = client.get("/docs/oauth2-redirect")
    assert response.status_code == 200, response.text
    assert response.headers["content-type"] == "text/html; charset=utf-8"
    assert "window.opener.swaggerUIRedirectOauth2" in response.text

* Each application that you have running on your computer has some process behind it, each running program, each window, etc. And there are normally many processes running **at the same time** while a computer is on.
* There can be **multiple processes** of the **same program** running at the same time.

[data-termynal]:before {
    content: '';
    position: absolute;
    top: 15px;
    left: 15px;
    display: inline-block;
    width: 15px;
    height: 15px;
    border-radius: 50%;
    /* A little hack to display the window buttons in one pseudo element. */
    background: #d9515d;
    -webkit-box-shadow: 25px 0 0 #f4c025, 50px 0 0 #3ec930;
            box-shadow: 25px 0 0 #f4c025, 50px 0 0 #3ec930;
}

[data-termynal]:after {

"_[...] Tôi đang sử dụng **FastAPI** vô cùng nhiều vào những ngày này. [...] Tôi thực sự đang lên kế hoạch sử dụng nó cho tất cả các nhóm **dịch vụ ML tại Microsoft**. Một vài trong số đó đang tích hợp vào sản phẩm lõi của **Window** và một vài sản phẩm cho **Office**._"

<div style="text-align: right; margin-right: 10%;">Kabir Khan - <strong>Microsoft</strong> <a href="https://github.com/tiangolo/fastapi/pull/26" target="_blank"><small>(ref)</small></a></div>

    <script>
        'use strict';
        function run () {
            var oauth2 = window.opener.swaggerUIRedirectOauth2;
            var sentState = oauth2.state;
            var redirectUrl = oauth2.redirectUrl;
            var isValid, qp, arr;

            if (/code|token|error/.test(window.location.hash)) {
                qp = window.location.hash.substring(1).replace('?', '&');
            } else {

Wenn das Programm nun Dinge in den Arbeitsspeicher lädt, zum Beispiel ein Modell für maschinelles Lernen in einer Variablen oder den Inhalt einer großen Datei in einer Variablen, verbraucht das alles **einen Teil des Arbeitsspeichers (RAM – Random Access Memory)** des Servers.