///

```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 }

In this case, you can use `typing.Dict` (or just `dict` in Python 3.9 and above):

{* ../../docs_src/extra_models/tutorial005_py39.py hl[6] *}


## Recap { #recap }

Use multiple Pydantic models and inherit freely for each case.

But if you need to access variables and objects from the same **FastAPI** app, or you need to perform small background tasks (like sending an email notification), you can simply just use `BackgroundTasks`.

## Recap { #recap }

///

Like `stored_item_model.model_copy(update=update_data)`:

{* ../../docs_src/body_updates/tutorial002_py310.py hl[33] *}

### Partial updates recap { #partial-updates-recap }

In summary, to apply partial updates you would:

* (Optionally) use `PATCH` instead of `PUT`.
* Retrieve the stored data.
* Put that data in a Pydantic model.

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.

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>.

{* ../../docs_src/path_params_numeric_validations/tutorial006_an_py39.py hl[13] *}

## Recap { #recap }

You could also use it to generate code automatically, for clients that communicate with your API. For example, frontend, mobile or IoT applications.

## Recap, step by step { #recap-step-by-step }

### Step 1: import `FastAPI` { #step-1-import-fastapi }

{* ../../docs_src/first_steps/tutorial001.py hl[1] *}

And the same way as before, you can use `File()` to set additional parameters, even for `UploadFile`:

{* ../../docs_src/request_files/tutorial003_an_py39.py hl[11,18:20] *}

## Recap { #recap }

In that case, the URL would be: `/files//home/johndoe/myfile.txt`, with a double slash (`//`) between `files` and `home`.

///

## Recap { #recap }

With **FastAPI**, by using short, intuitive and standard Python type declarations, you get:

* Editor support: error checks, autocompletion, etc.