- **Security:**
Java serialization poses security risks, especially related to deserialization vulnerabilities.

- **Version Compatibility:**
With Java serialization, even minor changes to a class (like adding a field) can break compatibility.

- **Cross-Language Compatibility:**

	default:
		panic("invalid format")
	}

	// Update checksum.
	// This field is special in that it is terminated by a NULL then space.
	var f formatter
	field := b.toV7().chksum()
	chksum, _ := b.computeChecksum() // Possible values are 256..128776
	f.formatOctal(field[:7], chksum) // Never fails since 128776 < 262143
	field[7] = ' '
}

// computeChecksum computes the checksum for the header block.

             * necessarily populated with header data because they're not writing
             * the header, only their body. But for whatever reason one might wish
             * to populate fields if the writeXxx operation needs this header data
             * for whatever reason. I copy over the uid here so it appears correct
             * in logging output. Logging of andx segments of messages inadvertantly

</div>

## Forbid Extra Headers

In some special use cases (probably not very common), you might want to **restrict** the headers that you want to receive.

You can use Pydantic's model configuration to `forbid` any `extra` fields:

//// tab | Python 3.10+

```Python hl_lines="10"
{!> ../../docs_src/header_param_models/tutorial002_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="10"

                newApi("Method", "SourceKt.setFool(boolean)")
            )
        }
    }

    @Test
    fun `new top-level kotlin types`() {

        // Singleton INSTANCE fields of `object`s are public

        checkNotBinaryCompatibleKotlin(
            v2 = """

            interface Foo

            class Bar

            enum class Bazar

# Body - Nested Models

With **FastAPI**, you can define, validate, document, and use arbitrarily deeply nested models (thanks to Pydantic).

## List fields

You can define an attribute to be a subtype. For example, a Python `list`:

//// tab | Python 3.10+

```Python hl_lines="12"
{!> ../../docs_src/body_nested_models/tutorial001_py310.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="14"

            exclusiveMaximum: false
            default: 20
            example: 20
        - name: sort
          in: query
          description: Sorted field name
          required: false
          schema:
            type: string
            example: score
        - name: fields.label
          in: query
          description: Filtered label name
          required: false
          style: form
          explode: true

        }
    }

    @Test
    public void searchTestWithWildcard() throws Exception {
        String field = "filetype";
        String query = "others";
        String wcQuery1 = "othe*";
        String wcQuery2 = "oth??s";
        Map<String, String> params = new HashMap<>();
        params.put("q", field + ":" + query);
        params.put("num", "100");

                    ), "An additional response must be a dict"
                    field = route.response_fields.get(additional_status_code)
                    additional_field_schema: Optional[Dict[str, Any]] = None
                    if field:
                        additional_field_schema = get_schema_from_model_field(
                            field=field,
                            schema_generator=schema_generator,

Mehr erfahren Sie am Ende dieser Seite.

///

## Zusätzliche Argumente für `Field`

Wenn Sie `Field()` mit Pydantic-Modellen verwenden, können Sie ebenfalls zusätzliche `examples` deklarieren:

//// tab | Python 3.10+

```Python hl_lines="2  8-11"
{!> ../../docs_src/schema_extra_example/tutorial002_py310.py!}