1 changed files with 63 additions and 0 deletions
@ -0,0 +1,63 @@ |
|||
# Return a Response Directly |
|||
|
|||
When you create a **FastAPI** *path operation* you can normally return any data from it: a `dict`, a `list`, a Pydantic model, a database model, etc. |
|||
|
|||
By default, **FastAPI** would automatically convert that return value to JSON using the `jsonable_encoder` explained in [JSON Compatible Encoder](../tutorial/encoder.md){.internal-link target=_blank}. |
|||
|
|||
Then, behind the scenes, it would put that JSON-compatible data (e.g. a `dict`) inside of a `JSONResponse` that would be used to send the response to the client. |
|||
|
|||
But you can return a `JSONResponse` directly from your *path operations*. |
|||
|
|||
It might be useful, for example, to return custom headers or cookies. |
|||
|
|||
## Return a `Response` |
|||
|
|||
In fact, you can return any `Response` or any sub-class of it. |
|||
|
|||
!!! tip |
|||
`JSONResponse` itself is a sub-class of `Response`. |
|||
|
|||
And when you return a `Response`, **FastAPI** will pass it directly. |
|||
|
|||
It won't do any data conversion with Pydantic models, it won't convert the contents to any type, etc. |
|||
|
|||
This gives you a lot of flexibility. You can return any data type, override any data declaration or validation, etc. |
|||
|
|||
## Using the `jsonable_encoder` in a `Response` |
|||
|
|||
Because **FastAPI** doesn't do any change to a `Response` you return, you have to make sure it's contents are ready for it. |
|||
|
|||
For example, you cannot put a Pydantic model in a `JSONResponse` without first converting it to a `dict` with all the data types (like `datetime`, `UUID`, etc) converted to JSON-compatible types. |
|||
|
|||
For those cases, you can use the `jsonable_encoder` to convert your data before passing it to a response: |
|||
|
|||
```Python hl_lines="6-7 21-22" |
|||
{!../../../docs_src/response_directly/tutorial001.py!} |
|||
``` |
|||
|
|||
!!! note "Technical Details" |
|||
You could also use `from starlette.responses import JSONResponse`. |
|||
|
|||
**FastAPI** provides the same `starlette.responses` as `fastapi.responses` just as a convenience for you, the developer. But most of the available responses come directly from Starlette. |
|||
|
|||
## Returning a custom `Response` |
|||
|
|||
The example above shows all the parts you need, but it's not very useful yet, as you could have just returned the `item` directly, and **FastAPI** would put it in a `JSONResponse` for you, converting it to a `dict`, etc. All that by default. |
|||
|
|||
Now, let's see how you could use that to return a custom response. |
|||
|
|||
Let's say that you want to return an <a href="https://en.wikipedia.org/wiki/XML" class="external-link" target="_blank">XML</a> response. |
|||
|
|||
You could put your XML content in a string, put it in a `Response`, and return it: |
|||
|
|||
```Python hl_lines="1 18" |
|||
{!../../../docs_src/response_directly/tutorial002.py!} |
|||
``` |
|||
|
|||
## Notes |
|||
|
|||
When you return a `Response` directly its data is not validated, converted (serialized), nor documented automatically. |
|||
|
|||
But you can still document it as described in [Additional Responses in OpenAPI](additional-responses.md){.internal-link target=_blank}. |
|||
|
|||
You can see in later sections how to use/declare these custom `Response`s while still having automatic data conversion, documentation, etc. |
Loading…
Reference in new issue