{* ../../docs_src/query_params_str_validations/tutorial006_an_py39.py hl[9] *}

### Required, can be `None` { #required-can-be-none }

You can declare that a parameter can accept `None`, but that it's still required. This would force clients to send a value, even if the value is `None`.

# Response Model - Return Type { #response-model-return-type }

You can declare the type used for the response by annotating the *path operation function* **return type**.

You can use **type annotations** the same way you would for input data in function **parameters**, you can use Pydantic models, lists, dictionaries, scalar values like integers, booleans, etc.

{* ../../docs_src/response_model/tutorial001_01_py310.py hl[16,21] *}

There is a `#contributing` channel on the community Slack which you can use
to ask any questions.

## Finding issues to work on

If you are looking for good first issues, take a look at the list of [good first issues](https://github.com/gradle/gradle/labels/good%20first%20issue) that should be actionable and ready for a contribution.

For **TypeScript clients**, <a href="https://heyapi.dev/" class="external-link" target="_blank">Hey API</a> is a purpose-built solution, providing an optimized experience for the TypeScript ecosystem.

You can think of `APIRouter` as a "mini `FastAPI`" class.

All the same options are supported.

All the same `parameters`, `responses`, `dependencies`, `tags`, etc.

/// tip

In this example, the variable is called `router`, but you can name it however you want.

///

But you can configure the **application server** to trust the *forwarded* headers sent by the **proxy**. If you are using FastAPI CLI, you can use the *CLI Option* `--forwarded-allow-ips` to tell it from which IPs it should trust those *forwarded* headers.

* Many PRs don't have tests, you can **remind** them to add tests, or you can even **suggest** some tests yourself. That's one of the things that consume most time and you can help a lot with that.

* Then also comment what you tried, that way I'll know that you checked it. 🤓

## Create a Pull Request { #create-a-pull-request }

### Read Heroes { #read-heroes }

We can **read** `Hero`s from the database using a `select()`. We can include a `limit` and `offset` to paginate the results.

{* ../../docs_src/sql_databases/tutorial001_an_py310.py ln[48:55] hl[51:52,54] *}

### Read One Hero { #read-one-hero }

We can **read** a single `Hero`.

{* ../../docs_src/sql_databases/tutorial001_an_py310.py ln[58:63] hl[60] *}

So, you can look for that specific exception inside the dependency with `except SomeException`.

In the same way, you can use `finally` to make sure the exit steps are executed, no matter if there was an exception or not.

{* ../../docs_src/dependencies/tutorial007_py39.py hl[3,5] *}

## Sub-dependencies with `yield` { #sub-dependencies-with-yield }

/// warning

This is a more or less advanced section. If you are just starting, you can skip it.

You don't necessarily need OAuth2 scopes, and you can handle authentication and authorization however you want.

But OAuth2 with scopes can be nicely integrated into your API (with OpenAPI) and your API docs.