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Adds integration of the Chameleon template language to FastAPI.

Project description


Adds integration of the Chameleon template language to FastAPI. If you are interested in Jinja instead, see the sister project:


Simply pip install fastapi_chameleon.


This is easy to use. Just create a folder within your web app to hold the templates such as:

├── templates
│   ├── home
│   │   └──
│   └── shared
│       └──

In the app startup, tell the library about the folder you wish to use:

import os
from pathlib import Path
import fastapi_chameleon

dev_mode = True

BASE_DIR = Path(__file__).resolve().parent
template_folder = str(BASE_DIR / 'templates')
fastapi_chameleon.global_init(template_folder, auto_reload=dev_mode)

Then just decorate the FastAPI view methods (works on sync and async methods):'/')
async def home_post(request: Request):
    form = await request.form()
    vm = PersonViewModel(**form) 

    return vm.dict() # {'first':'Michael', 'last':'Kennedy', ...}

The view method should return a dict to be passed as variables/values to the template.

If a fastapi.Response is returned, the template is skipped and the response along with status_code and other values is directly passed through. This is common for redirects and error responses not meant for this page template.

Friendly 404s and errors

A common technique for user-friendly sites is to use a custom HTML page for 404 responses. This is especially important in FastAPI because FastAPI returns a 404 response + JSON by default. This library has support for friendly 404 pages using the fastapi_chameleon.not_found() function.

Here's an example:

async def item(item_id: int):
    item = service.get_item_by_id(item_id)
    if not item:
    return item.dict()

This will render a 404 response with using the template file templates/errors/ You can specify another template to use for the response, but it's not required.

If you need to return errors other than Not Found (status code 404), you can use a more generic function: fastapi_chameleon.generic_error(template_file: str, status_code: int). This function will allow you to return different status codes. It's generic, thus you'll have to pass a path to your error template file as well as a status code you want the user to get in response. For example:

async def item(item_id: int):
    item = service.get_item_by_id(item_id)
    if not item:

    return item.dict()

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