Context Function error while using Jinja2 when trying to build templates

Question

Im following ChristopherGS's tutorial for FASTapi but i'm stuck on part 6 because I believe his syntax may be already deprecated.

I get AttributeError: module 'jinja2' has no attribute 'contextfunction at the end when the program stops. How do I solve this, I've been stuck here for 3 days.

This is my code:

from fastapi.templating import Jinja2Templates

from typing import Optional, Any
from pathlib import Path

from app.schemas import RecipeSearchResults, Recipe, RecipeCreate
from app.recipe_data import RECIPES


BASE_PATH = Path(__file__).resolve().parent
TEMPLATES = Jinja2Templates(directory=str(BASE_PATH / "templates"))


app = FastAPI(title="Recipe API", openapi_url="/openapi.json")

api_router = APIRouter()


# Updated to serve a Jinja2 template
# https://www.starlette.io/templates/
# https://jinja.palletsprojects.com/en/3.0.x/templates/#synopsis
@api_router.get("/", status_code=200)
def root(request: Request) -> dict:
    """
    Root GET
    """
    return TEMPLATES.TemplateResponse(
        "index.html",
        {"request": request, "recipes": RECIPES},
    )


@api_router.get("/recipe/{recipe_id}", status_code=200, response_model=Recipe)
def fetch_recipe(*, recipe_id: int) -> Any:
    """
    Fetch a single recipe by ID
    """

    result = [recipe for recipe in RECIPES if recipe["id"] == recipe_id]
    if not result:
        # the exception is raised, not returned - you will get a validation
        # error otherwise.
        raise HTTPException(
            status_code=404, detail=f"Recipe with ID {recipe_id} not found"
        )

    return result[0]

if __name__ == "__main__":
    # Use this for debugging purposes only
    import uvicorn

    uvicorn.run(app, host="0.0.0.0", port=8001, log_level="debug")

Answer 1

It could be due to the version mismatch bewteen jinja and starlette(fastapi). I faced similar issue with the latest fastapi docker image(python3.9). It was resolved by installing an older version of jinja2.

Try downgrading jinja2, if you are using jinja2 >3.0.3:

pip install jinja2==3.0.3

Other option would be to upgrade fastapi/starlette.

Ref:

1. FastAPI Jinja2Templates - Error while running initialising templates?
2. https://github.com/pallets/jinja/blob/1b714c7e82c73575d1dba48f560db07fe9a5cb74/CHANGES.rst#version-310