func (z *ChecksumInfo) 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 "PartNumber":
			z.PartNumber, err = dc.ReadInt()

from fastapi import Depends, FastAPI, HTTPException, Query
from sqlmodel import Field, Session, SQLModel, create_engine, select
from typing_extensions import Annotated


class HeroBase(SQLModel):
    name: str = Field(index=True)
    age: Union[int, None] = Field(default=None, index=True)


class Hero(HeroBase, table=True):
    id: Union[int, None] = Field(default=None, primary_key=True)
    secret_name: str

from typing import Union

from fastapi import Depends, FastAPI, HTTPException, Query
from sqlmodel import Field, Session, SQLModel, create_engine, select


class HeroBase(SQLModel):
    name: str = Field(index=True)
    age: Union[int, None] = Field(default=None, index=True)


class Hero(HeroBase, table=True):
    id: Union[int, None] = Field(default=None, primary_key=True)
    secret_name: str


class HeroPublic(HeroBase):
    id: int

	}

	return nil
}

// IsDaysNull returns true if days field is null
func (e Expiration) IsDaysNull() bool {
	return e.Days == ExpirationDays(0)
}

// IsDateNull returns true if date field is null
func (e Expiration) IsDateNull() bool {
	return e.Date.Time.IsZero()
}

// IsNull returns true if both date and days fields are null
func (e Expiration) IsNull() bool {

        catch ( IOException e ) {
            throw new PACDecodingException("Malformed kerberos ticket", e);
        }

        Enumeration<?> fields = sequence.getObjects();
        while ( fields.hasMoreElements() ) {
            ASN1TaggedObject tagged = ASN1Util.as(ASN1TaggedObject.class, fields);
            switch ( tagged.getTagNo() ) {
            case 0:// Kerberos version

func (z *allTierStats) 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 "ts":
			var zb0002 uint32

	}

	if t.StorageClass == "" {
		return errXMLNotWellFormed
	}
	return nil
}

// IsDateNull returns true if date field is null
func (t Transition) IsDateNull() bool {
	return t.Date.Time.IsZero()
}

// IsNull returns true if both date and days fields are null
func (t Transition) IsNull() bool {
	return t.StorageClass == ""
}

                public interface $TEST_INTERFACE_SIMPLE_NAME {
                    String field = "value";
                    void method();
                }
            """
            : """
                public class $TEST_INTERFACE_SIMPLE_NAME {
                    public String field = "value";
                    public void method() { }
                    public $TEST_INTERFACE_SIMPLE_NAME() { }

...then because `description` has a default value, if you **don't return anything** for that field, it will still have that **default value**.

### Model for Output Response Data

If you interact with the docs and check the response, even though the code didn't add anything in one of the `description` fields, the JSON response contains the default value (`null`):

<div class="screenshot">

The `HeroUpdate` *data model* is somewhat special, it has **all the same fields** that would be needed to create a new hero, but all the fields are **optional** (they all have a default value). This way, when you update a hero, you can send just the fields that you want to update.

Because all the **fields actually change** (the type now includes `None` and they now have a default value of `None`), we need to **re-declare** them.