fastapi/docs/en/docs/tutorial/request-form-models.md

79 lines
2.1 KiB
Markdown

# 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
```
///
/// note
This is supported since FastAPI version `0.113.0`. 🤓
///
## Pydantic Models for Forms
You just need to declare a **Pydantic model** with the fields you want to receive as **form fields**, and then declare the parameter as `Form`:
{* ../../docs_src/request_form_models/tutorial001_an_py39.py hl[9:11,15] *}
**FastAPI** will **extract** the data for **each field** from the **form data** in the request and give you the Pydantic model you defined.
## Check the Docs
You can verify it in the docs UI at `/docs`:
<div class="screenshot">
<img src="/img/tutorial/request-form-models/image01.png">
</div>
## Forbid Extra Form Fields
In some special use cases (probably not very common), you might want to **restrict** the form fields to only those declared in the Pydantic model. And **forbid** any **extra** fields.
/// note
This is supported since FastAPI version `0.114.0`. 🤓
///
You can use Pydantic's model configuration to `forbid` any `extra` fields:
{* ../../docs_src/request_form_models/tutorial002_an_py39.py hl[12] *}
If a client tries to send some extra data, they will receive an **error** response.
For example, if the client tries to send the form fields:
* `username`: `Rick`
* `password`: `Portal Gun`
* `extra`: `Mr. Poopybutthole`
They will receive an error response telling them that the field `extra` is not allowed:
```json
{
"detail": [
{
"type": "extra_forbidden",
"loc": ["body", "extra"],
"msg": "Extra inputs are not permitted",
"input": "Mr. Poopybutthole"
}
]
}
```
## Summary
You can use Pydantic models to declare form fields in FastAPI. 😎