///

## Multiple models

Here's a general idea of how the models could look like with their password fields and the places where they are used:

//// tab | Python 3.10+

```Python hl_lines="7  9  14  20  22  27-28  31-33  38-39"
{!> ../../docs_src/extra_models/tutorial001_py310.py!}
```

////

	case nil:

	// These are ordered and grouped to match ../../go/ast/ast.go
	case *ast.Field:
		if len(n.Names) == 0 && context == ctxField {
			f.walk(&n.Type, ctxEmbedType, visit)
		} else {
			f.walk(&n.Type, ctxType, visit)
		}
	case *ast.FieldList:
		for _, field := range n.List {
			f.walk(field, context, visit)
		}
	case *ast.BadExpr:
	case *ast.Ident:
	case *ast.Ellipsis:

            builder.field(SESSION_ID, sessionId);
        }
        if (method != null) {
            builder.field(METHOD, method);
        }
        if (url != null) {
            builder.field(URL, url);
        }
        if (parentUrl != null) {
            builder.field(PARENT_URL, parentUrl);
        }
        if (depth != null) {
            builder.field(DEPTH, depth);
        }

                    "type": "missing",
                    "loc": ["body", "grant_type"],
                    "msg": "Field required",
                    "input": None,
                },
                {
                    "type": "missing",
                    "loc": ["body", "username"],
                    "msg": "Field required",
                    "input": None,
                },
                {

	public static final field INSTANCE Lmockwebserver3/SocketPolicy$DisconnectAtStart;
}

public final class mockwebserver3/SocketPolicy$DisconnectDuringRequestBody : mockwebserver3/SocketPolicy {
	public static final field INSTANCE Lmockwebserver3/SocketPolicy$DisconnectDuringRequestBody;
}

public final class mockwebserver3/SocketPolicy$DisconnectDuringResponseBody : mockwebserver3/SocketPolicy {

            {
                "type": "missing",
                "loc": ["body", "username"],
                "msg": "Field required",
                "input": {},
            },
            {
                "type": "missing",
                "loc": ["body", "password"],
                "msg": "Field required",
                "input": {},
            },
        ]
    }


@needs_pydanticv2
@needs_py39

	public static final field DISCONNECT_DURING_RESPONSE_BODY Lokhttp3/mockwebserver/SocketPolicy;
	public static final field DO_NOT_READ_REQUEST_BODY Lokhttp3/mockwebserver/SocketPolicy;
	public static final field EXPECT_CONTINUE Lokhttp3/mockwebserver/SocketPolicy;
	public static final field FAIL_HANDSHAKE Lokhttp3/mockwebserver/SocketPolicy;
	public static final field KEEP_OPEN Lokhttp3/mockwebserver/SocketPolicy;

  // It is machine-readable.
  // This field cannot be empty for new Events.
  optional string type = 11;

  // deprecatedSource is the deprecated field assuring backward compatibility with core.v1 Event type.
  // +optional
  optional k8s.io.api.core.v1.EventSource deprecatedSource = 12;

  // deprecatedFirstTimestamp is the deprecated field assuring backward compatibility with core.v1 Event type.
  // +optional

    }

    @Override
    public Field getField() {
        return field;
    }

    /**
     * プロパティとして認識しているpublicフィールドを設定します。
     *
     * @param field
     *            プロパティとして認識するpublicフィールド
     */
    public void setField(final Field field) {
        this.field = field;
        if (field != null && ModifierUtil.isPublic(field)) {
            readable = true;

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel, Field

app = FastAPI()


class Item(BaseModel):
    name: str = Field(examples=["Foo"])
    description: Union[str, None] = Field(default=None, examples=["A very nice Item"])
    price: float = Field(examples=[35.4])
    tax: Union[float, None] = Field(default=None, examples=[3.2])


@app.put("/items/{item_id}")