Zum Beispiel könnten Sie eine Datei `main.py` haben mit:

```Python hl_lines="3"
import os

name = os.getenv("MY_NAME", "World")
print(f"Hello {name} from Python")
```

/// tip | Tipp

Das zweite Argument von [`os.getenv()`](https://docs.python.org/3.8/library/os.html#os.getenv) ist der Defaultwert, der zurückgegeben wird.

<img src="/img/tutorial/generate-clients/image02.png">

Ayrıca gönderilecek payload için de otomatik tamamlama alırsınız:

<img src="/img/tutorial/generate-clients/image03.png">

/// tip | İpucu

`name` ve `price` için otomatik tamamlamaya dikkat edin; bunlar FastAPI uygulamasında, `Item` modelinde tanımlanmıştı.

///

Gönderdiğiniz veriler için satır içi hatalar (inline errors) da alırsınız:

与声明查询参数一样，包含默认值的模型属性是可选的，否则就是必选的。把默认值设为 `None` 可使其变为可选。

例如，上述模型声明如下 JSON "object"（即 Python `dict`）：

```JSON
{
    "name": "Foo",
    "description": "An optional description",
    "price": 45.2,
    "tax": 3.5
}
```

...由于 `description` 和 `tax` 是可选的（默认值为 `None`），下面的 JSON "object" 也有效：

```JSON
{
    "name": "Foo",
    "price": 45.2
}
```

## 声明为参数 { #declare-it-as-a-parameter }

		t.Errorf("Read failed: read %d %v; want 1, nil", n, err)
	}
	if got, want := r.Len(), 0; got != want {
		t.Errorf("r.Len(): got %d, want %d", got, want)
	}
}

var UnreadRuneErrorTests = []struct {
	name string
	f    func(*Reader)
}{
	{"Read", func(r *Reader) { r.Read([]byte{0}) }},
	{"ReadByte", func(r *Reader) { r.ReadByte() }},
	{"UnreadRune", func(r *Reader) { r.UnreadRune() }},

        sink.writeDecimalLong(varyHeaders.size.toLong()).writeByte('\n'.code)
        for (i in 0 until varyHeaders.size) {
          sink
            .writeUtf8(varyHeaders.name(i))
            .writeUtf8(": ")
            .writeUtf8(varyHeaders.value(i))
            .writeByte('\n'.code)
        }

        sink.writeUtf8(StatusLine(protocol, code, message).toString()).writeByte('\n'.code)

                && !NtlmPasswordAuthentication.NULL.equals(auth);
    }

    void ssn139() throws IOException {
        final Name calledName = new Name(address.firstCalledName(), 0x20, null);
        do {
            /* These Socket constructors attempt to connect before SO_TIMEOUT can be applied
            if (localAddr == null) {

 *
 */
public class AdminSuggestAction extends FessAdminAction {

    /**
     * Default constructor.
     */
    public AdminSuggestAction() {
        super();
    }

    /** Role name for admin suggest operations */
    public static final String ROLE = "admin-suggest";

    // ===================================================================================

  }

  @CollectionFeature.Require(absent = SUPPORTS_ADD)
  @CollectionSize.Require(absent = ZERO)
  /*
   * absent = ZERO isn't required, since unmodList.add() must
   * throw regardless, but it keeps the method name accurate.
   */
  public void testAdd_unsupportedPresent() {
    assertThrows(UnsupportedOperationException.class, () -> getList().add(e0()));
  }

  @CollectionFeature.Require(value = {SUPPORTS_ADD, ALLOWS_NULL_VALUES})

With `Form` you can declare the same configurations as with `Body` (and `Query`, `Path`, `Cookie`), including validation, examples, an alias (e.g. `user-name` instead of `username`), etc.

/// info

`Form` is a class that inherits directly from `Body`.

///

/// tip

	}{
		{"s.title", []any{"Murder on the Orient Express", "The Robots of Dawn", "Pigs Have Wings"}},
		{"s.authorInfo.yearRange", []any{[]any{1890.0, 1976.0}, []any{1920.0, 1992.0}, []any{1881.0, 1975.0}}},
		{"s.authorInfo.name", []any{"Agatha Christie", "Isaac Asimov", "P. G. Wodehouse"}},
		{"s.authorInfo.yearRange[0]", []any{1890.0, 1920.0, 1881.0}},
		{"s.publicationHistory[0].pages", []any{256.0, 336.0, Missing{}}},
	}
	for i, tc := range cases {