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

## Forbid Extra Form Fields { #forbid-extra-form-fields }

In some special use cases (probably not very common), you might want to **restrict** the form fields to only those declared in the Pydantic model. And **forbid** any **extra** fields.

/// note

This is supported since FastAPI version `0.114.0`. 🤓

///

**FastAPI**'s `UploadFile` inherits directly from **Starlette**'s `UploadFile`, but adds some necessary parts to make it compatible with **Pydantic** and the other parts of FastAPI.

///

## What is "Form Data" { #what-is-form-data }

The way HTML forms (`<form></form>`) sends the data to the server normally uses a "special" encoding for that data, it's different from JSON.

**FastAPI** will make sure to read that data from the right place instead of JSON.

The spec also states that the `username` and `password` must be sent as form data (so, no JSON here).

### `scope` { #scope }

The spec also says that the client can send another form field "`scope`".

The form field name is `scope` (in singular), but it is actually a long string with "scopes" separated by spaces.

Each "scope" is just a string (without spaces).

///

And if you click it, you have a little authorization form to type a `username` and `password` (and other optional fields):

<img src="/img/tutorial/security/image02.png">

/// note

It doesn't matter what you type in the form, it won't work yet. But we'll get there.

///

            int position = 0;
            int offset = 0;
            for (String word : words) {
                if (!word.isEmpty()) {
                    int startOffset = text.indexOf(word, offset);
                    int endOffset = startOffset + word.length();

                    // Handle decimal numbers
                    if (word.matches("\\d+") && startOffset > 0 && text.charAt(startOffset - 1) == '.') {

        work = (leftt >>> 2 ^ right) & 0x33333333;
        right ^= work;
        leftt ^= work << 2;
        work = (right >>> 16 ^ leftt) & 0x0000ffff;
        leftt ^= work;
        right ^= work << 16;
        work = (right >>> 4 ^ leftt) & 0x0f0f0f0f;
        leftt ^= work;
        right ^= work << 4;
        outInts[0] = right;
        outInts[1] = leftt;
    }

    /// Encrypt a block of bytes.

## Program and Process { #program-and-process }

We will talk a lot about the running "**process**", so it's useful to have clarity about what it means, and what's the difference with the word "**program**".

### What is a Program { #what-is-a-program }

The word **program** is commonly used to describe many things:

* The **code** that you write, the **Python files**.

`FastAPI` is actually a sub-class of `Starlette`. So, if you already know or use Starlette, most of the functionality will work the same way.

With **FastAPI** you get all of **Starlette**'s features (as FastAPI is just Starlette on steroids):

## `examples` in JSON Schema - OpenAPI { #examples-in-json-schema-openapi }

When using any of:

* `Path()`
* `Query()`
* `Header()`
* `Cookie()`
* `Body()`
* `Form()`
* `File()`

you can also declare a group of `examples` with additional information that will be added to their **JSON Schemas** inside of **OpenAPI**.

### `Body` with `examples` { #body-with-examples }

///

/// warning

Make sure to **always** use the **exec form** of the `CMD` instruction, as explained below.

///

#### Use `CMD` - Exec Form { #use-cmd-exec-form }

The <a href="https://docs.docker.com/reference/dockerfile/#cmd" class="external-link" target="_blank">`CMD`</a> Docker instruction can be written using two forms:

✅ **Exec** form:

```Dockerfile
# ✅ Do this