Here's where it becomes important to be able to declare <abbr title="greater than"><code>gt</code></abbr> and not just <abbr title="greater than or equal"><code>ge</code></abbr>. As with it you can require, for example, that a value must be greater than `0`, even if it is less than `1`.

So, `0.5` would be a valid value. But `0.0` or `0` would not.

And the same for <abbr title="less than"><code>lt</code></abbr>.

            "schemas": {
                "Model": {"title": "Model", "type": "object", "properties": {}},
                "Model2": {
                    "title": "Model2",
                    "required": ["a"],
                    "type": "object",
                    "properties": {"a": {"$ref": "#/components/schemas/Model"}},
                },
                "Model3": {
                    "title": "Model3",

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

# Abhängigkeiten { #dependencies }

**FastAPI** hat ein sehr mächtiges, aber intuitives **<abbr title="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“ { #what-is-dependency-injection }

            "schemas": {
                "Item": {
                    "title": "Item",
                    "required": ["name", "age"],
                    "type": "object",
                    "properties": {
                        "name": {"title": "Name", "type": "string"},
                        "age": {
                            "title": "Age",
                            "anyOf": [

        },
        "components": {
            "schemas": {
                "HTTPValidationError": {
                    "title": "HTTPValidationError",
                    "type": "object",
                    "properties": {
                        "detail": {
                            "title": "Detail",
                            "type": "array",
                            "items": {"$ref": "#/components/schemas/ValidationError"},

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

                            "title": "Location",
                            "type": "array",
                            "items": {
                                "anyOf": [{"type": "string"}, {"type": "integer"}]
                            },
                        },
                        "msg": {"title": "Message", "type": "string"},
                        "type": {"title": "Error Type", "type": "string"},

            "p": {
                "anyOf": [
                    {"items": {"type": "string"}, "type": "array"},
                    {"type": "null"},
                ],
                "title": "P",
            },
        },
        "title": body_model_name,
        "type": "object",
    }


@pytest.mark.parametrize(
    "path",
    ["/optional-list-str", "/model-optional-list-str"],
)

### 导入 `APIRouter`

你可以导入它并通过与 `FastAPI` 类相同的方式创建一个「实例」：

```Python hl_lines="1  3" title="app/routers/users.py"
{!../../docs_src/bigger_applications/app/routers/users.py!}
```

### 使用 `APIRouter` 的*路径操作*

然后你可以使用它来声明*路径操作*。

使用方式与 `FastAPI` 类相同：

```Python hl_lines="6  11  16" title="app/routers/users.py"
{!../../docs_src/bigger_applications/app/routers/users.py!}
```