A middleware to handle ETag for Starlette or FastAPI.

pip install etag-middleware

from etag import ETagMiddleware
from fastapi import FastAPI
from fastapi.middleware import Middleware

app = FastAPI(middleware=[Middleware(ETagMiddleware)])

from etag import ETagMiddleware
from starlette.applications import Starlette
from starlette.middleware import Middleware

app = Starlette(middleware=[Middleware(ETagMiddleware)])

1. It won't compute ETag for requests with body size less than 80 bytes by default. Beacause ETag and If-None-Match increase more than 70 bytes to the response header, and computing ETag consumes CPU. You can adjust it by setting minimum_size:

   app = FastAPI(middleware=[Middleware(ETagMiddleware, minimum_size=0)])

2. It won't compute ETag for StreamingResponse. Because it will delay sending the response until collected all its body and consumes more memory.

3. It compares ETag with If-None-Match for FileResponse.