# Dependencies

**FastAPI** has a very powerful but intuitive **<abbr title="also known as components, resources, providers, services, injectables">Dependency Injection</abbr>** system.

It is designed to be very simple to use, and to make it very easy for any developer to integrate other components with **FastAPI**.

## What is "Dependency Injection"

## Pydantic

Die ganze Datenvalidierung wird hinter den Kulissen von <a href="https://pydantic-docs.helpmanual.io/" class="external-link" target="_blank">Pydantic</a> durchgeführt, Sie profitieren also von dessen Vorteilen. Und Sie wissen, dass Sie in guten Händen sind.

Sie können für Typ Deklarationen auch `str`, `float`, `bool` und viele andere komplexe Datentypen verwenden.

After a week, the token will be expired and the user will not be authorized and will have to sign in again to get a new token. And if the user (or a third party) tried to modify the token to change the expiration, you would be able to discover it, because the signatures would not match.

   * was acquired, or null if no connection was acquired. The acquired connection will also be
   * given to [connectionUser] who may (for example) assign it to a [RealCall.connection].
   *
   * This confirms the returned connection is healthy before returning it. If this encounters any
   * unhealthy connections in its search, this will clean them up.
   *

```Python hl_lines="2"
@app.get('/')
def results():
    results = some_library()
    return results
```

---

Wenn Ihre Anwendung (irgendwie) mit nichts anderem kommunizieren und auf dessen Antwort warten muss, verwenden Sie `async def`.

---

Wenn Sie sich unsicher sind, verwenden Sie einfach `def`.

---

* **Intuitive**: Great editor support. <abbr title="also known as auto-complete, autocompletion, IntelliSense">Completion</abbr> everywhere. Less time debugging.
* **Easy**: Designed to be easy to use and learn. Less time reading docs.
* **Short**: Minimize code duplication. Multiple features from each parameter declaration. Fewer bugs.

	// Create a new post policy.
	policy := newPostPolicyBytesV2(bucketName, objectName, expirationTime)
	// Only need the encoding.
	encodedPolicy := base64.StdEncoding.EncodeToString(policy)

	// Presign with V4 signature based on the policy.
	signature := calculateSignatureV2(encodedPolicy, secretKey)

	formData := map[string]string{
		"AWSAccessKeyId":              accessKey,

Sie können aber auch <a href="https://typer.tiangolo.com/typer-cli/" class="external-link" target="_blank">Typer CLI</a> verwenden und erhalten dann Autovervollständigung für Kommandos in Ihrem Terminal, nach dem Sie dessen Vervollständigung installiert haben.

Wenn Sie Typer CLI installieren, können Sie die Vervollständigung installieren mit:

<div class="termy">

```console
$ typer --install-completion

		// Initialize erasure code format on disks
		format, err = initFormatErasure(GlobalContext, storageDisks, setCount, setDriveCount, deploymentID, sErrs)
		if err != nil {
			return nil, nil, err
		}

		// Assign globalDeploymentID() on first run for the
		// minio server managing the first disk
		globalDeploymentIDPtr.Store(&format.ID)
		return storageDisks, format, nil
	}

    * Doğrulayıcılar en kompleks data şemalarının bile temiz ve kolay bir şekilde tanımlanmasına izin veriyor, ve hepsi JSON şeması olarak dokümante ediliyor
    * Pydantic, JSON objen ne kadar derin (nested) olursa olsun doğrulamasını ve gösterimini yapıyor
* **Genişletilebilir**: