Os status codes na faixa dos 400 significam que houve um erro por parte do cliente.

Você se lembra de todos aqueles erros (e piadas) a respeito do "**404 Not Found**"?

## Use o `HTTPException`

Para retornar ao cliente *responses* HTTP com erros, use o `HTTPException`.

### Import `HTTPException`

```Python hl_lines="1"

pkg net/netip, func ParseAddr(string) (Addr, error)
pkg net/netip, func ParseAddrPort(string) (AddrPort, error)
pkg net/netip, func ParsePrefix(string) (Prefix, error)
pkg net/netip, func PrefixFrom(Addr, int) Prefix
pkg net/netip, method (*Addr) UnmarshalBinary([]uint8) error
pkg net/netip, method (*Addr) UnmarshalText([]uint8) error
pkg net/netip, method (*AddrPort) UnmarshalBinary([]uint8) error

pkg database/sql, method (*Conn) BeginTx(context.Context, *TxOptions) (*Tx, error)
pkg database/sql, method (*Conn) Close() error
pkg database/sql, method (*Conn) ExecContext(context.Context, string, ...interface{}) (Result, error)
pkg database/sql, method (*Conn) PingContext(context.Context) error
pkg database/sql, method (*Conn) PrepareContext(context.Context, string) (*Stmt, error)

func TestMultipleMany2Many(t *testing.T) {
	type Thing struct {
		ID int
	}

	type Person struct {
		ID       int
		Likes    []Thing `gorm:"many2many:likes"`
		Dislikes []Thing `gorm:"many2many:dislikes"`
	}

	checkStructRelation(t, &Person{},
		Relation{
			Name: "Likes", Type: schema.Many2Many, Schema: "Person", FieldSchema: "Thing",
			JoinTable: JoinTable{Name: "likes", Table: "likes"},

pkg net/http, var ErrServerClosed error
pkg net/http, var NoBody noBody
pkg net/mail, func ParseDate(string) (time.Time, error)
pkg net, method (*Buffers) Read([]uint8) (int, error)
pkg net, method (*Buffers) WriteTo(io.Writer) (int64, error)
pkg net, method (*Resolver) LookupAddr(context.Context, string) ([]string, error)
pkg net, method (*Resolver) LookupCNAME(context.Context, string) (string, error)

      read += r;
    } else if (r == 0) {
      TF_SetStatus(status, TF_OUT_OF_RANGE, "Read fewer bytes than requested");
      break;
    } else if (errno == EINTR || errno == EAGAIN) {
      // Retry
    } else {
      TF_SetStatusFromIOError(status, errno, posix_file->filename);
      break;
    }
  }

  return read;
}

}  // namespace tf_random_access_file

pkg net/http, const StatusTooEarly ideal-int
pkg net/http, method (*Client) CloseIdleConnections()
pkg os, const ModeType = 2401763328
pkg os, func UserHomeDir() (string, error)
pkg os, method (*File) SyscallConn() (syscall.RawConn, error)
pkg os, method (*ProcessState) ExitCode() int
pkg os/exec, method (ExitError) ExitCode() int
pkg reflect, method (*MapIter) Key() Value
pkg reflect, method (*MapIter) Next() bool

	}
	if context == ctxAssign2 {
		context = ctxExpr
	}
	if context == ctxEmbedType {
		error_(sel.Pos(), "cannot embed C type")
	}
	goname := sel.Sel.Name
	if goname == "errno" {
		error_(sel.Pos(), "cannot refer to errno directly; see documentation")
		return
	}
	if goname == "_CMalloc" {
		error_(sel.Pos(), "cannot refer to C._CMalloc; use C.malloc")
		return
	}
	if goname == "malloc" {

<img src="/img/python-types/image06.png">

Notice that this means "`one_person` is an **instance** of the class `Person`".

It doesn't mean "`one_person` is the **class** called `Person`".

## Pydantic models

<a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> is a Python library to perform data validation.

You declare the "shape" of the data as classes with attributes.

pkg syscall (windows-386), const ERROR_PRIVILEGE_NOT_HELD = 1314
pkg syscall (windows-386), const ERROR_PRIVILEGE_NOT_HELD Errno
pkg syscall (windows-amd64), const ERROR_PRIVILEGE_NOT_HELD = 1314
pkg syscall (windows-amd64), const ERROR_PRIVILEGE_NOT_HELD Errno

# CL 86160044 os: Implement symlink support for Windows, Michael Fraenkel <******@****.***>