"soFar","preFilters","cached","combinator","base","skip","checkNonElements","doneName","oldCache","newCache","elementMatcher","matchers","condense","newUnmatched","mapped","setMatcher","postFilter","postFinder","postSelector","temp","matcherOut","preMap","postMap","preexisting","contexts","multipleContexts","matcherIn","matcherFromTokens","checkContext","leadingRelative","implicitRelative","matchContext","matchAnyContext","elementMatchers","setMatchers","bySet","byElement","superMatcher","outerm...

"soFar","preFilters","cached","combinator","base","skip","checkNonElements","doneName","oldCache","newCache","elementMatcher","matchers","condense","newUnmatched","mapped","setMatcher","postFilter","postFinder","postSelector","temp","matcherOut","preMap","postMap","preexisting","contexts","multipleContexts","matcherIn","matcherFromTokens","checkContext","leadingRelative","implicitRelative","matchContext","matchAnyContext","elementMatchers","setMatchers","bySet","byElement","superMatcher","outerm...

This is not a limitation of **FastAPI**, it's part of the HTTP protocol.

///

## Recap { #recap }

But even if you **fill the data** and click "Execute", because the docs UI works with **JavaScript**, the cookies won't be sent, and you will see an **error** message as if you didn't write any values.

///

## Recap { #recap }

As these keys may not necessarily be part of the OpenAPI specification, some OpenAPI tools, for example [the OpenAPI validator](https://validator.swagger.io/), may not work with your generated schema.

///

## Recap { #recap }

You can use Pydantic's `Field` to declare extra validations and metadata for model attributes.

This is not a limitation of **FastAPI**, it's part of the HTTP protocol.

///

## Recap { #recap }

```
X-Token: foo
X-Token: bar
```

The response would be like:

```JSON
{
    "X-Token values": [
        "bar",
        "foo"
    ]
}
```

## Recap { #recap }

Declare headers with `Header`, using the same common pattern as `Query`, `Path` and `Cookie`.

///

```Python hl_lines="1"
async def needy_dependency(fresh_value: str = Depends(get_value, use_cache=False)):
    return {"fresh_value": fresh_value}
```

////

## Recap { #recap }

Apart from all the fancy words used here, the **Dependency Injection** system is quite simple.

Just functions that look the same as the *path operation functions*.

<img src="/img/tutorial/path-operation-configuration/image04.png">

Check how deprecated and non-deprecated *path operations* look like:

<img src="/img/tutorial/path-operation-configuration/image05.png">

## Recap { #recap }

And all these thousands of *path operations* can be as small as 3 lines:

{* ../../docs_src/security/tutorial002_an_py310.py hl[30:32] *}

## Recap { #recap }

You can now get the current user directly in your *path operation function*.

We are already halfway there.