tiangolo.fastapi/docs/en/docs/tutorial/request-forms-and-files.md

Request Forms and Files

You can define files and form fields at the same time using File and Form.

/// info

To receive uploaded files and/or form data, first install python-multipart.

Make sure you create a virtual environment{.internal-link target=_blank}, activate it, and then install it, for example:

$ pip install python-multipart

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Import File and Form

//// tab | Python 3.9+

{!> ../../../docs_src/request_forms_and_files/tutorial001_an_py39.py!}

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//// tab | Python 3.8+

{!> ../../../docs_src/request_forms_and_files/tutorial001_an.py!}

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//// tab | Python 3.8+ non-Annotated

/// tip

Prefer to use the Annotated version if possible.

///

{!> ../../../docs_src/request_forms_and_files/tutorial001.py!}

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Define File and Form parameters

Create file and form parameters the same way you would for Body or Query:

//// tab | Python 3.9+

{!> ../../../docs_src/request_forms_and_files/tutorial001_an_py39.py!}

////

//// tab | Python 3.8+

{!> ../../../docs_src/request_forms_and_files/tutorial001_an.py!}

////

//// tab | Python 3.8+ non-Annotated

/// tip

Prefer to use the Annotated version if possible.

///

{!> ../../../docs_src/request_forms_and_files/tutorial001.py!}

////

The files and form fields will be uploaded as form data and you will receive the files and form fields.

And you can declare some of the files as bytes and some as UploadFile.

/// warning

You can declare multiple File and Form parameters in a path operation, but you can't also declare Body fields that you expect to receive as JSON, as the request will have the body encoded using multipart/form-data instead of application/json.

This is not a limitation of FastAPI, it's part of the HTTP protocol.

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Recap

Use File and Form together when you need to receive data and files in the same request.