type UserMigrateColumn struct {
		ID       uint
		Name     string
		Salary   float64
		Birthday time.Time `gorm:"precision:4"`
	}

	DB.Migrator().DropTable(&UserMigrateColumn{})

	DB.AutoMigrate(&UserMigrateColumn{})

	type UserMigrateColumn2 struct {
		ID                  uint
		Name                string    `gorm:"size:128"`
		Salary              float64   `gorm:"precision:2"`

// row. They have an output for each input row.
//
// Some types of a queries are not valid. For example, an aggregation
// function combined with a row function is meaningless ("AVG(s.Age) +
// s.Salary"). Analysis determines if such a scenario exists so an
// error can be returned.

var (
	// Fatal error for query processing.
	errNestedAggregation      = errors.New("Cannot nest aggregations")

from typing import Annotated, Union

from fastapi import FastAPI
from pydantic import AfterValidator

app = FastAPI()

data = {
    "isbn-9781529046137": "The Hitchhiker's Guide to the Galaxy",
    "imdb-tt0371724": "The Hitchhiker's Guide to the Galaxy",
    "isbn-9781439512982": "Isaac Asimov: The Complete Stories, Vol. 2",
}


def check_valid_id(id: str):
    if not id.startswith(("isbn-", "imdb-")):

import random
from typing import Annotated

from fastapi import FastAPI
from pydantic import AfterValidator

app = FastAPI()

data = {
    "isbn-9781529046137": "The Hitchhiker's Guide to the Galaxy",
    "imdb-tt0371724": "The Hitchhiker's Guide to the Galaxy",
    "isbn-9781439512982": "Isaac Asimov: The Complete Stories, Vol. 2",
}


def check_valid_id(id: str):
    if not id.startswith(("isbn-", "imdb-")):

        }
    ]
}
```

## Zusammenfassung { #summary }

Sie können **Pydantic-Modelle** verwenden, um **Query-Parameter** in **FastAPI** zu deklarieren. 😎

/// tip | Tipp

Spoiler-Alarm: Sie können auch Pydantic-Modelle verwenden, um Cookies und Header zu deklarieren, aber darüber werden Sie später im Tutorial lesen. 🤫

    response = client.get("/items?id=isbn-9781529046137")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "id": "isbn-9781529046137",
        "name": "The Hitchhiker's Guide to the Galaxy",
    }


def test_get_item_does_not_exist(client: TestClient):
    response = client.get("/items?id=isbn-nope")
    assert response.status_code == 200, response.text

Then with `random.choice()` we can get a **random value** from the list, so, we get a tuple with `(id, name)`. It will be something like `("imdb-tt0371724", "The Hitchhiker's Guide to the Galaxy")`.

Then we **assign those two values** of the tuple to the variables `id` and `name`.

So, if the user didn't provide an item ID, they will still receive a random suggestion.

Потім, використовуючи `random.choice()`, ми можемо отримати випадкове значення зі списку, тобто отримуємо кортеж із `(id, name)`. Це може бути щось на зразок `("imdb-tt0371724", "The Hitchhiker's Guide to the Galaxy")`.

Далі ми **присвоюємо ці два значення** кортежу змінним `id` і `name`.

Тож, якщо користувач не вказав ID елемента, він все одно отримає випадкову рекомендацію.

Se você definir como `--forwarded-allow-ips="*"`, ele confiará em todos os IPs de entrada.

Se o seu **servidor** estiver atrás de um **proxy** confiável e somente o proxy falar com ele, isso fará com que ele aceite seja qual for o IP desse **proxy**.

<div class="termy">

```console
$ fastapi run --forwarded-allow-ips="*"

   * response to a sender.
   *
   * @since 8.0
   */
  public static final byte ACK = 6;

  /**
   * Bell ('\a'): A character for use when there is a need to call for human attention. It may
   * control alarm or attention devices.
   *
   * @since 8.0
   */
  public static final byte BEL = 7;

  /**
   * Backspace ('\b'): A format effector which controls the movement of the printing position one