/// 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. 😎

///

As SQLModel is based on SQLAlchemy, you can easily use **any database supported** by SQLAlchemy (which makes them also supported by SQLModel), like:

///

## Add `.gitignore` { #add-gitignore }

If you are using **Git** (you should), add a `.gitignore` file to exclude everything in your `.venv` from Git.

/// tip

If you used [`uv`](https://github.com/astral-sh/uv) to create the virtual environment, it already did this for you, you can skip this step. 😎

///

/// tip

Do this **once**, right after you create the virtual environment.

///

It's a very simple program.

But now imagine that you were writing it from scratch.

At some point you would have started the definition of the function, you had the parameters ready...

But then you have to call "that method that converts the first letter to upper case".

Was it `upper`? Was it `uppercase`? `first_uppercase`? `capitalize`?

Then, you try with the old programmer's friend, editor autocompletion.

In most cases, when you create a web API, you want it to be **always running**, uninterrupted, so that your clients can always access it. This is of course, unless you have a specific reason why you want it to run only in certain situations, but most of the time you want it constantly running and **available**.

### In a Remote Server { #in-a-remote-server }

For example, let's say that you want to use [`orjson`](https://github.com/ijl/orjson) with some settings.

Let's say you want it to return indented and formatted JSON, so you want to use the orjson option `orjson.OPT_INDENT_2`.

You could create a `CustomORJSONResponse`. The main thing you have to do is create a `Response.render(content)` method that returns the content as `bytes`:

{* ../../docs_src/custom_response/tutorial009c_py310.py hl[9:14,17] *}

    * **CORS**
    * **Cookie Sessions**
    * ...and more.

### Deploy your app (optional)

You can optionally deploy your FastAPI app to [FastAPI Cloud](https://fastapicloud.com), go and join the waiting list if you haven't. 🚀

If you already have a **FastAPI Cloud** account (we invited you from the waiting list 😉), you can deploy your application with one command.

<div class="termy">

```console
$ fastapi deploy

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      required: true
  - type: textarea
    id: context
    attributes:
      label: Context (optional)
      description: |
        How has this issue affected you? What are you trying to accomplish?
        Providing context helps us come up with a solution that is most useful in the real world
    validations:
      required: false
  - type: textarea
    id: steps-to-reproduce

This includes `pydantic.v1`, which is no longer supported in Python 3.14 and above.

If you want to use the latest features of Python, you will need to make sure you use Pydantic v2.

///

If you have an old FastAPI app with Pydantic v1, here I'll show you how to migrate it to Pydantic v2, and the **features in FastAPI 0.119.0** to help you with a gradual migration.

## Official Guide { #official-guide }

## Use a `Response` parameter { #use-a-response-parameter }

You can declare a parameter of type `Response` in your *path operation function*.

And then you can set cookies in that *temporal* response object.

{* ../../docs_src/response_cookies/tutorial002_py310.py hl[1, 8:9] *}

And then you can return any object you need, as you normally would (a `dict`, a database model, etc).

/// tip

When writing the code to document a callback, it might be useful to imagine that you are that *external developer*. And that you are currently implementing the *external API*, not *your API*.

Temporarily adopting this point of view (of the *external developer*) can help you feel like it's more obvious where to put the parameters, the Pydantic model for the body, for the response, etc. for that *external API*.