# ADR-0006 - Use of Provider APIs in Gradle

## Date

2024-06-21

## Context

/// tip

Prefer to use the `Annotated` version if possible.

///

```Python hl_lines="10"
{!> ../../docs_src/security/tutorial001.py!}
```

////

But that is still not that useful.

Let's make it give us the current user.

## Create a user model

First, let's create a Pydantic user model.

The same way we use Pydantic to declare bodies, we can use it anywhere else:

///

## Use cases

Some use cases include:

* Converting non-JSON request bodies to JSON (e.g. <a href="https://msgpack.org/index.html" class="external-link" target="_blank">`msgpack`</a>).
* Decompressing gzip-compressed request bodies.
* Automatically logging all request bodies.

## Handling custom request body encodings

## Custom CDN for JavaScript and CSS

Let's say that you want to use a different <abbr title="Content Delivery Network">CDN</abbr>, for example you want to use `https://unpkg.com/`.

This could be useful if for example you live in a country that restricts some URLs.

### Disable the automatic docs

The first step is to disable the automatic docs, as by default, those use the default CDN.

/// tip

You could use any other SQL or NoSQL database library you want (in some cases called <abbr title="Object Relational Mapper, a fancy term for a library where some classes represent SQL tables and instances represent rows in those tables">"ORMs"</abbr>), FastAPI doesn't force you to use anything. 😎

///

# Form Models

You can use **Pydantic models** to declare **form fields** in FastAPI.

/// info

To use forms, first install <a href="https://github.com/Kludex/python-multipart" class="external-link" target="_blank">`python-multipart`</a>.

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and then install it, for example:

```console
$ pip install python-multipart
```

///

With it, you can use <a href="https://docs.pytest.org/" class="external-link" target="_blank">pytest</a> directly with **FastAPI**.

## Using `TestClient`

/// info

To use `TestClient`, first install <a href="https://www.python-httpx.org" class="external-link" target="_blank">`httpx`</a>.

In this case, this `__call__` is what **FastAPI** will use to check for additional parameters and sub-dependencies, and this is what will be called to pass a value to the parameter in your *path operation function* later.

## Parameterize the instance

And now, we can use `__init__` to declare the parameters of the instance that we can use to "parameterize" the dependency:

     * build the model for a POM from the repository, use {@link #setModelSource(ModelSource)} in combination with a
     * {@link FileModelSource} instead.
     *
     * @param pomFile The POM file of the project to build the effective model for, may be {@code null} to build the
     *            model of some POM from the repository.
     * @return This request, never {@code null}.
     * @deprecated Use {@link #setPomPath(Path)} instead.
     */

You probably want to test the external provider once, but not necessarily call it for every test that runs.

In this case, you can override the dependency that calls that provider, and use a custom dependency that returns a mock user, only for your tests.

### Use the `app.dependency_overrides` attribute

For these cases, your **FastAPI** application has an attribute `app.dependency_overrides`, it is a simple `dict`.