## Pin your `fastapi` version { #pin-your-fastapi-version }

The first thing you should do is to "pin" the version of **FastAPI** you are using to the specific latest version that you know works correctly for your application.

For example, let's say you are using version `0.112.0` in your app.

///

Pour apprendre les bases du HTTPS, du point de vue d'un utilisateur, consultez <a href="https://howhttps.works/"
class="external-link" target="_blank">https://howhttps.works/</a>.

Maintenant, du point de vue d'un développeur, voici plusieurs choses à avoir en tête en pensant au HTTPS :

Do you want to just have a `str`? Or just a `dict`? Or a database class model instance directly? It all works the same way.

You actually don't have users that log in to your application but robots, bots, or other systems, that have just an access token? Again, it all works the same.

	if count1 != 1 || count2 != 3 {
		t.Errorf("multiple count in chain should works")
	}

	tx := DB.Model(&User{}).Where("name = ?", user1.Name).Session(&gorm.Session{})
	tx.Count(&count1)
	tx.Or("name in ?", []string{user2.Name, user3.Name}).Count(&count2)
	if count1 != 1 || count2 != 3 {
		t.Errorf("count after new session should works")
	}

	var count3 int64

package tests

import (
	"database/sql"
	"time"

	"gorm.io/gorm"
)

// User has one `Account` (has one), many `Pets` (has many) and `Toys` (has many - polymorphic)
// He works in a Company (belongs to), he has a Manager (belongs to - single-table), and also managed a Team (has many - single-table)
// He speaks many languages (many to many) and has many friends (many to many - single-table)
// His pet also has one Toy (has one - polymorphic)

Additional IP Rights Grant (Patents)

"This implementation" means the copyrightable works distributed by
Google as part of the Go project.

Google hereby grants to You a perpetual, worldwide, non-exclusive,
no-charge, royalty-free, irrevocable (except as stated in this section)
patent license to make, have made, use, offer to sell, sell, import,
transfer and otherwise run, modify and propagate the contents of this

///

## Declare model attributes { #declare-model-attributes }

You can then use `Field` with model attributes:

{* ../../docs_src/body_fields/tutorial001_an_py310.py hl[11:14] *}

`Field` works the same way as `Query`, `Path` and `Body`, it has all the same parameters, etc.

/// note | Technical Details

These examples are intentionally simple, but show how it all works.

In the chapters about security, there are utility functions that are implemented in this same way.

If you understood all this, you already know how those utility tools for security work underneath.

Swagger UI will handle it behind the scenes for you, but it needs this "redirect" helper.

///

### Create a *path operation* to test it { #create-a-path-operation-to-test-it }

Now, to be able to test that everything works, create a *path operation*:

{* ../../docs_src/custom_docs_ui/tutorial001.py hl[36:38] *}

### Test it { #test-it }

## First Steps { #first-steps }

Let's see a very simple example. It will be so simple that it is not very useful, for now.

But this way we can focus on how the **Dependency Injection** system works.

### Create a dependency, or "dependable" { #create-a-dependency-or-dependable }

Let's first focus on the dependency.