"` structure with `struct_size` field "   \
                                "set to " #SIZE_VALUE_NAME                \
                                ". Found `struct_size` = 0.");            \
    }                                                                     \
  } while (0)

// Macro to verify that the field NAME of STRUCT_OBJ is not null.

    /** The key of the configuration. e.g. url */
    String INDEX_FIELD_URL = "index.field.url";

    /** The key of the configuration. e.g. doc_id */
    String INDEX_FIELD_doc_id = "index.field.doc_id";

    /** The key of the configuration. e.g. _id */
    String INDEX_FIELD_ID = "index.field.id";

    /** The key of the configuration. e.g. _version */

func (z *PartialOperation) DecodeMsg(dc *msgp.Reader) (err error) {
	var field []byte
	_ = field
	var zb0001 uint32
	zb0001, err = dc.ReadMapHeader()
	if err != nil {
		err = msgp.WrapError(err)
		return
	}
	for zb0001 > 0 {
		zb0001--
		field, err = dc.ReadMapKeyPtr()
		if err != nil {
			err = msgp.WrapError(err)
			return
		}
		switch msgp.UnsafeString(field) {
		case "Bucket":
			z.Bucket, err = dc.ReadString()

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

{* ../../docs_src/separate_openapi_schemas/tutorial001_py310.py ln[1:15] hl[14] *}

...then the `description` field will **not be required**. Because it has a default value of `None`.

### Input Model in Docs { #input-model-in-docs }

You can confirm that in the docs, the `description` field doesn't have a **red asterisk**, it's not marked as required:

<div class="screenshot">

from sqlmodel import Field, Session, SQLModel, create_engine

engine = create_engine("postgresql+psycopg://postgres:postgres@localhost/db")


class User(SQLModel, table=True):
    id: int | None = Field(default=None, primary_key=True)
    name: str


app = FastAPI()


def get_session():
    with Session(engine) as session:
        yield session

from typing import Annotated

from fastapi import Body, FastAPI
from pydantic import BaseModel, Field

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = Field(
        default=None, title="The description of the item", max_length=300
    )
    price: float = Field(gt=0, description="The price must be greater than zero")
    tax: float | None = None


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

import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.mockito.Mockito.mock;

import java.lang.reflect.Field;
import java.util.Arrays;

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.params.ParameterizedTest;

        // Given
        String filename = "\\\\server\\share\\file.txt";
        trans2GetDfsReferral = new Trans2GetDfsReferral(mockConfig, filename);

        // Set path field (inherited from parent)
        Field pathField = trans2GetDfsReferral.getClass().getSuperclass().getSuperclass().getDeclaredField("path");
        pathField.setAccessible(true);
        pathField.set(trans2GetDfsReferral, filename);

     */
    Waiter(boolean unused) {}

    Waiter() {
      // avoid volatile write, write is made visible by subsequent CAS on waitersField field
      putThread(this, Thread.currentThread());
    }

    // non-volatile write to the next field. Should be made visible by a subsequent CAS on
    // waitersField.
    void setNext(@Nullable Waiter next) {
      putNext(this, next);
    }