# Abhängigkeiten

**FastAPI** hat ein sehr mächtiges, aber intuitives **<abbr title="Dependency Injection – Einbringen von Abhängigkeiten: Auch bekannt als Komponenten, Ressourcen, Provider, Services, Injectables">Dependency Injection</abbr>** System.

Es ist so konzipiert, sehr einfach zu verwenden zu sein und es jedem Entwickler sehr leicht zu machen, andere Komponenten mit **FastAPI** zu integrieren.

## Was ist „Dependency Injection“

Verwenden Sie bitte trotzdem die `Annotated`-Version. 😉

///

////

### Erforderlich mit Ellipse (`...`)

Es gibt eine Alternative, die explizit deklariert, dass ein Wert erforderlich ist. Sie können als Default das <abbr title='Zeichenfolge, die einen Wert direkt darstellt, etwa 1, "hallowelt", True, None'>Literal</abbr> `...` setzen:

        formatTree(result) == '''<chapter>
    <section>
        <title>Properties</title>
        <para>No properties</para>
    </section>
    <section>
        <title>Methods</title>
        <para>No methods</para>
    </section>
    <section>
        <title>Script blocks</title>
        <table>
            <title>Script blocks - Class</title>
            <thead>
                <tr>

                    "title": "Message",
                    "required": ["title", "description"],
                    "type": "object",
                    "properties": {
                        "title": {"title": "Title", "type": "string"},
                        "description": {"title": "Description", "type": "string"},
                    },
                },
                "ValidationError": {
                    "title": "ValidationError",

                "Item": {
                    "title": "Item",
                    "required": ["name", "price"],
                    "type": "object",
                    "properties": {
                        "name": {"title": "Name", "type": "string"},
                        "description": {"title": "Description", "type": "string"},
                        "price": {"title": "Price", "type": "number"},

                            "title": "Location",
                        },
                        "msg": {"type": "string", "title": "Message"},
                        "type": {"type": "string", "title": "Error Type"},
                    },
                    "type": "object",
                    "required": ["loc", "msg", "type"],
                    "title": "ValidationError",
                },
            }

                    },
                },
                "Item": {
                    "title": "Item",
                    "required": ["title", "size"],
                    "type": "object",
                    "properties": {
                        "title": {"title": "Title", "type": "string"},
                        "size": {"title": "Size", "type": "integer"},
                    },
                },

om/blog/building-a-machine-learning-microservice-with-fastapi/ title: Building a Machine Learning Microservice with FastAPI - author: Ravgeet Dhillon - Twilio link: https://www.twilio.com/en-us/blog/booking-appointments-twilio-notion-fastapi title: Booking Appointments with Twilio, Notion, and FastAPI - author: Abhinav Tripathi - Microsoft Blogs link: https://devblogs.microsoft.com/cosmosdb/azure-cosmos-db-python-and-fastapi/ title: Write a Python data layer with Azure Cosmos DB and FastAPI - author:...

                "Item": {
                    "title": "Item",
                    "type": "object",
                    "properties": {
                        "name": {"title": "Name", "type": "string"},
                        "description": {"title": "Description", "type": "string"},
                        "price": {"title": "Price", "type": "number"},
                        "tax": {"title": "Tax", "type": "number", "default": 10.5},

                "Item": {
                    "title": "Item",
                    "required": ["name", "price"],
                    "type": "object",
                    "properties": {
                        "name": {"title": "Name", "type": "string"},
                        "description": IsDict(
                            {
                                "title": "Description",