Потокова передача даних¶
🌐 Переклад ШІ та людьми
Цей переклад виконано ШІ під керівництвом людей. 🤝
Можливі помилки через неправильне розуміння початкового змісту або неприродні формулювання тощо. 🤖
Ви можете покращити цей переклад, допомігши нам краще спрямовувати AI LLM.
Якщо ви хочете передавати потоком дані, які можна структурувати як JSON, див. Потокова передача JSON Lines.
Але якщо ви хочете передавати потоком чисті бінарні дані або строки, ось як це зробити.
Інформація
Додано у FastAPI 0.134.0.
Варіанти використання¶
Це можна використовувати, якщо ви хочете передавати потоком чисті строки, наприклад безпосередньо з виводу сервісу AI LLM.
Також це можна використати для потокової передачі великих бінарних файлів, коли ви надсилаєте кожний фрагмент даних під час читання, без потреби завантажувати все в пам'ять одразу.
Так само можна стрімити відео чи аудіо; їх навіть можна генерувати під час обробки та надсилання.
StreamingResponse з yield¶
Якщо ви оголосите response_class=StreamingResponse у вашій функції операції шляху, ви можете використовувати yield, щоб послідовно надсилати кожний фрагмент даних.
from collections.abc import AsyncIterable, Iterable
from fastapi import FastAPI
from fastapi.responses import StreamingResponse
app = FastAPI()
message = """
Rick: (stumbles in drunkenly, and turns on the lights) Morty! You gotta come on. You got--... you gotta come with me.
Morty: (rubs his eyes) What, Rick? What's going on?
Rick: I got a surprise for you, Morty.
Morty: It's the middle of the night. What are you talking about?
Rick: (spills alcohol on Morty's bed) Come on, I got a surprise for you. (drags Morty by the ankle) Come on, hurry up. (pulls Morty out of his bed and into the hall)
Morty: Ow! Ow! You're tugging me too hard!
Rick: We gotta go, gotta get outta here, come on. Got a surprise for you Morty.
"""
@app.get("/story/stream", response_class=StreamingResponse)
async def stream_story() -> AsyncIterable[str]:
for line in message.splitlines():
yield line
# Code below omitted 👇
👀 Full file preview
from collections.abc import AsyncIterable, Iterable
from fastapi import FastAPI
from fastapi.responses import StreamingResponse
app = FastAPI()
message = """
Rick: (stumbles in drunkenly, and turns on the lights) Morty! You gotta come on. You got--... you gotta come with me.
Morty: (rubs his eyes) What, Rick? What's going on?
Rick: I got a surprise for you, Morty.
Morty: It's the middle of the night. What are you talking about?
Rick: (spills alcohol on Morty's bed) Come on, I got a surprise for you. (drags Morty by the ankle) Come on, hurry up. (pulls Morty out of his bed and into the hall)
Morty: Ow! Ow! You're tugging me too hard!
Rick: We gotta go, gotta get outta here, come on. Got a surprise for you Morty.
"""
@app.get("/story/stream", response_class=StreamingResponse)
async def stream_story() -> AsyncIterable[str]:
for line in message.splitlines():
yield line
@app.get("/story/stream-no-async", response_class=StreamingResponse)
def stream_story_no_async() -> Iterable[str]:
for line in message.splitlines():
yield line
@app.get("/story/stream-no-annotation", response_class=StreamingResponse)
async def stream_story_no_annotation():
for line in message.splitlines():
yield line
@app.get("/story/stream-no-async-no-annotation", response_class=StreamingResponse)
def stream_story_no_async_no_annotation():
for line in message.splitlines():
yield line
@app.get("/story/stream-bytes", response_class=StreamingResponse)
async def stream_story_bytes() -> AsyncIterable[bytes]:
for line in message.splitlines():
yield line.encode("utf-8")
@app.get("/story/stream-no-async-bytes", response_class=StreamingResponse)
def stream_story_no_async_bytes() -> Iterable[bytes]:
for line in message.splitlines():
yield line.encode("utf-8")
@app.get("/story/stream-no-annotation-bytes", response_class=StreamingResponse)
async def stream_story_no_annotation_bytes():
for line in message.splitlines():
yield line.encode("utf-8")
@app.get("/story/stream-no-async-no-annotation-bytes", response_class=StreamingResponse)
def stream_story_no_async_no_annotation_bytes():
for line in message.splitlines():
yield line.encode("utf-8")
FastAPI передаватиме кожний фрагмент даних до StreamingResponse як є; він не намагатиметься перетворити його на JSON чи щось подібне.
Не-async функції операції шляху¶
Можна також використовувати звичайні функції def (без async) і так само застосовувати yield.
# Code above omitted 👆
@app.get("/story/stream-no-async", response_class=StreamingResponse)
def stream_story_no_async() -> Iterable[str]:
for line in message.splitlines():
yield line
# Code below omitted 👇
👀 Full file preview
from collections.abc import AsyncIterable, Iterable
from fastapi import FastAPI
from fastapi.responses import StreamingResponse
app = FastAPI()
message = """
Rick: (stumbles in drunkenly, and turns on the lights) Morty! You gotta come on. You got--... you gotta come with me.
Morty: (rubs his eyes) What, Rick? What's going on?
Rick: I got a surprise for you, Morty.
Morty: It's the middle of the night. What are you talking about?
Rick: (spills alcohol on Morty's bed) Come on, I got a surprise for you. (drags Morty by the ankle) Come on, hurry up. (pulls Morty out of his bed and into the hall)
Morty: Ow! Ow! You're tugging me too hard!
Rick: We gotta go, gotta get outta here, come on. Got a surprise for you Morty.
"""
@app.get("/story/stream", response_class=StreamingResponse)
async def stream_story() -> AsyncIterable[str]:
for line in message.splitlines():
yield line
@app.get("/story/stream-no-async", response_class=StreamingResponse)
def stream_story_no_async() -> Iterable[str]:
for line in message.splitlines():
yield line
@app.get("/story/stream-no-annotation", response_class=StreamingResponse)
async def stream_story_no_annotation():
for line in message.splitlines():
yield line
@app.get("/story/stream-no-async-no-annotation", response_class=StreamingResponse)
def stream_story_no_async_no_annotation():
for line in message.splitlines():
yield line
@app.get("/story/stream-bytes", response_class=StreamingResponse)
async def stream_story_bytes() -> AsyncIterable[bytes]:
for line in message.splitlines():
yield line.encode("utf-8")
@app.get("/story/stream-no-async-bytes", response_class=StreamingResponse)
def stream_story_no_async_bytes() -> Iterable[bytes]:
for line in message.splitlines():
yield line.encode("utf-8")
@app.get("/story/stream-no-annotation-bytes", response_class=StreamingResponse)
async def stream_story_no_annotation_bytes():
for line in message.splitlines():
yield line.encode("utf-8")
@app.get("/story/stream-no-async-no-annotation-bytes", response_class=StreamingResponse)
def stream_story_no_async_no_annotation_bytes():
for line in message.splitlines():
yield line.encode("utf-8")
Без анотації¶
Для потокової передачі бінарних даних немає потреби оголошувати анотацію типу, що повертається.
Оскільки FastAPI не намагатиметься перетворювати дані на JSON за допомогою Pydantic чи серіалізувати їх іншим чином, у цьому випадку анотація типу потрібна лише для вашого редактора та інструментів; FastAPI її не використовуватиме.
# Code above omitted 👆
@app.get("/story/stream-no-annotation", response_class=StreamingResponse)
async def stream_story_no_annotation():
for line in message.splitlines():
yield line
# Code below omitted 👇
👀 Full file preview
from collections.abc import AsyncIterable, Iterable
from fastapi import FastAPI
from fastapi.responses import StreamingResponse
app = FastAPI()
message = """
Rick: (stumbles in drunkenly, and turns on the lights) Morty! You gotta come on. You got--... you gotta come with me.
Morty: (rubs his eyes) What, Rick? What's going on?
Rick: I got a surprise for you, Morty.
Morty: It's the middle of the night. What are you talking about?
Rick: (spills alcohol on Morty's bed) Come on, I got a surprise for you. (drags Morty by the ankle) Come on, hurry up. (pulls Morty out of his bed and into the hall)
Morty: Ow! Ow! You're tugging me too hard!
Rick: We gotta go, gotta get outta here, come on. Got a surprise for you Morty.
"""
@app.get("/story/stream", response_class=StreamingResponse)
async def stream_story() -> AsyncIterable[str]:
for line in message.splitlines():
yield line
@app.get("/story/stream-no-async", response_class=StreamingResponse)
def stream_story_no_async() -> Iterable[str]:
for line in message.splitlines():
yield line
@app.get("/story/stream-no-annotation", response_class=StreamingResponse)
async def stream_story_no_annotation():
for line in message.splitlines():
yield line
@app.get("/story/stream-no-async-no-annotation", response_class=StreamingResponse)
def stream_story_no_async_no_annotation():
for line in message.splitlines():
yield line
@app.get("/story/stream-bytes", response_class=StreamingResponse)
async def stream_story_bytes() -> AsyncIterable[bytes]:
for line in message.splitlines():
yield line.encode("utf-8")
@app.get("/story/stream-no-async-bytes", response_class=StreamingResponse)
def stream_story_no_async_bytes() -> Iterable[bytes]:
for line in message.splitlines():
yield line.encode("utf-8")
@app.get("/story/stream-no-annotation-bytes", response_class=StreamingResponse)
async def stream_story_no_annotation_bytes():
for line in message.splitlines():
yield line.encode("utf-8")
@app.get("/story/stream-no-async-no-annotation-bytes", response_class=StreamingResponse)
def stream_story_no_async_no_annotation_bytes():
for line in message.splitlines():
yield line.encode("utf-8")
Це також означає, що з StreamingResponse у вас є свобода і відповідальність формувати та кодувати байти даних саме так, як їх потрібно надіслати, незалежно від анотацій типів. 🤓
Потік байтів¶
Один з основних сценаріїв - передавати потоком bytes замість строк; це, звісно, підтримується.
# Code above omitted 👆
@app.get("/story/stream-bytes", response_class=StreamingResponse)
async def stream_story_bytes() -> AsyncIterable[bytes]:
for line in message.splitlines():
yield line.encode("utf-8")
# Code below omitted 👇
👀 Full file preview
from collections.abc import AsyncIterable, Iterable
from fastapi import FastAPI
from fastapi.responses import StreamingResponse
app = FastAPI()
message = """
Rick: (stumbles in drunkenly, and turns on the lights) Morty! You gotta come on. You got--... you gotta come with me.
Morty: (rubs his eyes) What, Rick? What's going on?
Rick: I got a surprise for you, Morty.
Morty: It's the middle of the night. What are you talking about?
Rick: (spills alcohol on Morty's bed) Come on, I got a surprise for you. (drags Morty by the ankle) Come on, hurry up. (pulls Morty out of his bed and into the hall)
Morty: Ow! Ow! You're tugging me too hard!
Rick: We gotta go, gotta get outta here, come on. Got a surprise for you Morty.
"""
@app.get("/story/stream", response_class=StreamingResponse)
async def stream_story() -> AsyncIterable[str]:
for line in message.splitlines():
yield line
@app.get("/story/stream-no-async", response_class=StreamingResponse)
def stream_story_no_async() -> Iterable[str]:
for line in message.splitlines():
yield line
@app.get("/story/stream-no-annotation", response_class=StreamingResponse)
async def stream_story_no_annotation():
for line in message.splitlines():
yield line
@app.get("/story/stream-no-async-no-annotation", response_class=StreamingResponse)
def stream_story_no_async_no_annotation():
for line in message.splitlines():
yield line
@app.get("/story/stream-bytes", response_class=StreamingResponse)
async def stream_story_bytes() -> AsyncIterable[bytes]:
for line in message.splitlines():
yield line.encode("utf-8")
@app.get("/story/stream-no-async-bytes", response_class=StreamingResponse)
def stream_story_no_async_bytes() -> Iterable[bytes]:
for line in message.splitlines():
yield line.encode("utf-8")
@app.get("/story/stream-no-annotation-bytes", response_class=StreamingResponse)
async def stream_story_no_annotation_bytes():
for line in message.splitlines():
yield line.encode("utf-8")
@app.get("/story/stream-no-async-no-annotation-bytes", response_class=StreamingResponse)
def stream_story_no_async_no_annotation_bytes():
for line in message.splitlines():
yield line.encode("utf-8")
Користувацький PNGStreamingResponse¶
У наведених вище прикладах байти даних передавалися потоком, але у відповіді не було заголовка Content-Type, тому клієнт не знав, який тип даних він отримує.
Можна створити власний підклас StreamingResponse, який встановлює заголовок Content-Type відповідно до типу даних, що ви стрімите.
Наприклад, можна створити PNGStreamingResponse, який встановлює заголовок Content-Type у image/png за допомогою атрибута media_type:
# Code above omitted 👆
from fastapi.responses import StreamingResponse
# Code here omitted 👈
class PNGStreamingResponse(StreamingResponse):
media_type = "image/png"
# Code below omitted 👇
👀 Full file preview
import base64
from collections.abc import AsyncIterable, Iterable
from io import BytesIO
from fastapi import FastAPI
from fastapi.responses import StreamingResponse
image_base64 = "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"
binary_image = base64.b64decode(image_base64)
def read_image() -> BytesIO:
return BytesIO(binary_image)
app = FastAPI()
class PNGStreamingResponse(StreamingResponse):
media_type = "image/png"
@app.get("/image/stream", response_class=PNGStreamingResponse)
async def stream_image() -> AsyncIterable[bytes]:
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async", response_class=PNGStreamingResponse)
def stream_image_no_async() -> Iterable[bytes]:
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async-yield-from", response_class=PNGStreamingResponse)
def stream_image_no_async_yield_from() -> Iterable[bytes]:
with read_image() as image_file:
yield from image_file
@app.get("/image/stream-no-annotation", response_class=PNGStreamingResponse)
async def stream_image_no_annotation():
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async-no-annotation", response_class=PNGStreamingResponse)
def stream_image_no_async_no_annotation():
with read_image() as image_file:
for chunk in image_file:
yield chunk
Потім ви можете використати цей новий клас у response_class=PNGStreamingResponse у вашій функції операції шляху:
# Code above omitted 👆
@app.get("/image/stream", response_class=PNGStreamingResponse)
async def stream_image() -> AsyncIterable[bytes]:
with read_image() as image_file:
for chunk in image_file:
yield chunk
# Code below omitted 👇
👀 Full file preview
import base64
from collections.abc import AsyncIterable, Iterable
from io import BytesIO
from fastapi import FastAPI
from fastapi.responses import StreamingResponse
image_base64 = "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"
binary_image = base64.b64decode(image_base64)
def read_image() -> BytesIO:
return BytesIO(binary_image)
app = FastAPI()
class PNGStreamingResponse(StreamingResponse):
media_type = "image/png"
@app.get("/image/stream", response_class=PNGStreamingResponse)
async def stream_image() -> AsyncIterable[bytes]:
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async", response_class=PNGStreamingResponse)
def stream_image_no_async() -> Iterable[bytes]:
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async-yield-from", response_class=PNGStreamingResponse)
def stream_image_no_async_yield_from() -> Iterable[bytes]:
with read_image() as image_file:
yield from image_file
@app.get("/image/stream-no-annotation", response_class=PNGStreamingResponse)
async def stream_image_no_annotation():
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async-no-annotation", response_class=PNGStreamingResponse)
def stream_image_no_async_no_annotation():
with read_image() as image_file:
for chunk in image_file:
yield chunk
Симулювати файл¶
У цьому прикладі ми імітуємо файл за допомогою io.BytesIO - це об'єкт на кшталт файлу, який існує лише в пам'яті, але надає той самий інтерфейс.
Наприклад, ми можемо ітеруватися по ньому, щоб зчитати вміст, так само як і з файлом.
import base64
from collections.abc import AsyncIterable, Iterable
from io import BytesIO
from fastapi import FastAPI
from fastapi.responses import StreamingResponse
image_base64 = "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"
binary_image = base64.b64decode(image_base64)
def read_image() -> BytesIO:
return BytesIO(binary_image)
app = FastAPI()
class PNGStreamingResponse(StreamingResponse):
media_type = "image/png"
@app.get("/image/stream", response_class=PNGStreamingResponse)
async def stream_image() -> AsyncIterable[bytes]:
with read_image() as image_file:
for chunk in image_file:
yield chunk
# Code below omitted 👇
👀 Full file preview
import base64
from collections.abc import AsyncIterable, Iterable
from io import BytesIO
from fastapi import FastAPI
from fastapi.responses import StreamingResponse
image_base64 = "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"
binary_image = base64.b64decode(image_base64)
def read_image() -> BytesIO:
return BytesIO(binary_image)
app = FastAPI()
class PNGStreamingResponse(StreamingResponse):
media_type = "image/png"
@app.get("/image/stream", response_class=PNGStreamingResponse)
async def stream_image() -> AsyncIterable[bytes]:
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async", response_class=PNGStreamingResponse)
def stream_image_no_async() -> Iterable[bytes]:
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async-yield-from", response_class=PNGStreamingResponse)
def stream_image_no_async_yield_from() -> Iterable[bytes]:
with read_image() as image_file:
yield from image_file
@app.get("/image/stream-no-annotation", response_class=PNGStreamingResponse)
async def stream_image_no_annotation():
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async-no-annotation", response_class=PNGStreamingResponse)
def stream_image_no_async_no_annotation():
with read_image() as image_file:
for chunk in image_file:
yield chunk
Технічні деталі
Інші дві змінні, image_base64 та binary_image, - це зображення, закодоване в Base64, яке потім перетворюється на байти, щоб передати його в io.BytesIO.
Лише для того, щоб усе містилося в одному файлі для цього прикладу, і ви могли скопіювати його та запустити як є. 🥚
Використовуючи блок with, ми гарантуємо, що об'єкт, подібний до файлу, буде закрито після завершення генераторної функції (функції з yield). Тобто після завершення надсилання відповіді.
У цьому конкретному прикладі це не так важливо, адже це фальшивий файл у пам'яті (з io.BytesIO), але для справжнього файлу важливо переконатися, що файл закрито після завершення роботи з ним.
Файли та async¶
У більшості випадків об'єкти, подібні до файлів, за замовчуванням несумісні з async та await.
Наприклад, у них немає await file.read() або async for chunk in file.
І часто їх читання є блокувальною операцією (що може блокувати цикл подій), адже дані зчитуються з диска або мережі.
Інформація
Наведений вище приклад - виняток, адже об'єкт io.BytesIO вже в пам'яті, тож читання нічого не блокує.
Але в багатьох випадках читання файлу або схожого на файл об'єкта блокує виконання.
Щоб уникнути блокування циклу подій, просто оголосіть функцію операції шляху зі звичайним def замість async def. Тоді FastAPI виконуватиме її в працівнику пулу потоків, щоб не блокувати головний цикл.
# Code above omitted 👆
@app.get("/image/stream-no-async", response_class=PNGStreamingResponse)
def stream_image_no_async() -> Iterable[bytes]:
with read_image() as image_file:
for chunk in image_file:
yield chunk
# Code below omitted 👇
👀 Full file preview
import base64
from collections.abc import AsyncIterable, Iterable
from io import BytesIO
from fastapi import FastAPI
from fastapi.responses import StreamingResponse
image_base64 = "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"
binary_image = base64.b64decode(image_base64)
def read_image() -> BytesIO:
return BytesIO(binary_image)
app = FastAPI()
class PNGStreamingResponse(StreamingResponse):
media_type = "image/png"
@app.get("/image/stream", response_class=PNGStreamingResponse)
async def stream_image() -> AsyncIterable[bytes]:
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async", response_class=PNGStreamingResponse)
def stream_image_no_async() -> Iterable[bytes]:
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async-yield-from", response_class=PNGStreamingResponse)
def stream_image_no_async_yield_from() -> Iterable[bytes]:
with read_image() as image_file:
yield from image_file
@app.get("/image/stream-no-annotation", response_class=PNGStreamingResponse)
async def stream_image_no_annotation():
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async-no-annotation", response_class=PNGStreamingResponse)
def stream_image_no_async_no_annotation():
with read_image() as image_file:
for chunk in image_file:
yield chunk
Порада
Якщо вам потрібно викликати блокувальний код усередині async-функції або async-функцію зсередини блокувальної функції, ви можете скористатися Asyncer - спорідненою бібліотекою до FastAPI.
yield from¶
Коли ви ітеруєтеся по чомусь, наприклад по об'єкту, подібному до файлу, і робите yield для кожного елемента, можна також використати yield from, щоб віддавати кожен елемент напряму і пропустити цикл for.
Це не специфічно для FastAPI, це просто Python, але корисний трюк. 😎
# Code above omitted 👆
@app.get("/image/stream-no-async-yield-from", response_class=PNGStreamingResponse)
def stream_image_no_async_yield_from() -> Iterable[bytes]:
with read_image() as image_file:
yield from image_file
# Code below omitted 👇
👀 Full file preview
import base64
from collections.abc import AsyncIterable, Iterable
from io import BytesIO
from fastapi import FastAPI
from fastapi.responses import StreamingResponse
image_base64 = "iVBORw0KGgoAAAANSUhEUgAAAB0AAAAdCAYAAABWk2cPAAAAbnpUWHRSYXcgcHJvZmlsZSB0eXBlIGV4aWYAAHjadYzRDYAwCET/mcIRDoq0jGOiJm7g+NJK0vjhS4DjIEfHfZ20DKqSrrWZmyFQV5ctRMOLACxglNCcXk7zVqFzJzF8kV6R5vOJ97yVH78HjfYAtg0ged033ZgAAAoCaVRYdFhNTDpjb20uYWRvYmUueG1wAAAAAAA8P3hwYWNrZXQgYmVnaW49Iu+7vyIgaWQ9Ilc1TTBNcENlaGlIenJlU3pOVGN6a2M5ZCI/Pgo8eDp4bXBtZXRhIHhtbG5zOng9ImFkb2JlOm5zOm1ldGEvIiB4OnhtcHRrPSJYTVAgQ29yZSA0LjQuMC1FeGl2MiI+CiA8cmRmOlJERiB4bWxuczpyZGY9Imh0dHA6Ly93d3cudzMub3JnLzE5OTkvMDIvMjItcmRmLXN5bnRheC1ucyMiPgogIDxyZGY6RGVzY3JpcHRpb24gcmRmOmFib3V0PSIiCiAgICB4bWxuczpleGlmPSJodHRwOi8vbnMuYWRvYmUuY29tL2V4aWYvMS4wLyIKICAgIHhtbG5zOnRpZmY9Imh0dHA6Ly9ucy5hZG9iZS5jb20vdGlmZi8xLjAvIgogICBleGlmOlBpeGVsWERpbWVuc2lvbj0iMjkiCiAgIGV4aWY6UGl4ZWxZRGltZW5zaW9uPSIyOSIKICAgdGlmZjpJbWFnZVdpZHRoPSIyOSIKICAgdGlmZjpJbWFnZUxlbmd0aD0iMjkiCiAgIHRpZmY6T3JpZW50YXRpb249IjEiLz4KIDwvcmRmOlJERj4KPC94OnhtcG1ldGE+CiAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAKICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgIAogICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgCiAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAKICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgIAogICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgCiAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAKICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgIAogICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgCiAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAKICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgIAogICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgCiAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAKICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgIAogICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgCiAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAKICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgIAogICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgCiAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAKICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgIAogICAgICAgICAgICAgICAgICAgICAgICAgICAKPD94cGFja2V0IGVuZD0idyI/PnQkBZAAAAAEc0JJVAgICAh8CGSIAAABoklEQVRIx8VXwY7FIAjE5iXWU+P/f6RHPNW9LIaOoHYP+0yMShVkwNGG1lqjfy4HfaF0oyEEt+oSQqBaa//m9Wd6PlqhhbRMDiEQM3e59FNKw5qZHpnQfuPaW6lazsztvu/eElFj5j63lNLlMz2ttbZtVMu1MTGo5Sujn93gMzOllKiUQjHGB9QxxneZhJ5iwZ1rL2fwenoGeL0q3wVGhBPHMz0PeFccIfASEeWcO8xEROd50q6eAV6s1s5XXoncas1EKqVQznnwUBdJJmm1l3hmmdlOMrGO8Vl5gZ56Y0y8IZF0BuqkQWM4B6HXrRCKa1SEqyzEo7KK59RT/VHDjX3ZvSefeW3CO6O6vsiA1NrwVkxxAcYTCcHyTjZmJd00pugBQoTnzjvn+kzLBh9GtRDjhleZFwbx3kugP3GvFzdkqRlbDYw0u/HxKjuOw2QxZCGL5V5f4l7cd6qsffUa1DcLM9N1XcTMvep5ul1e4jNPtZfWGIkE6dI8MquXg/dS2CGVJQ2ushd5GmlxFdOw+1tRa32MY4zDQ9yaZ60J3/iX+QG4U3qGrFHmswAAAABJRU5ErkJggg=="
binary_image = base64.b64decode(image_base64)
def read_image() -> BytesIO:
return BytesIO(binary_image)
app = FastAPI()
class PNGStreamingResponse(StreamingResponse):
media_type = "image/png"
@app.get("/image/stream", response_class=PNGStreamingResponse)
async def stream_image() -> AsyncIterable[bytes]:
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async", response_class=PNGStreamingResponse)
def stream_image_no_async() -> Iterable[bytes]:
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async-yield-from", response_class=PNGStreamingResponse)
def stream_image_no_async_yield_from() -> Iterable[bytes]:
with read_image() as image_file:
yield from image_file
@app.get("/image/stream-no-annotation", response_class=PNGStreamingResponse)
async def stream_image_no_annotation():
with read_image() as image_file:
for chunk in image_file:
yield chunk
@app.get("/image/stream-no-async-no-annotation", response_class=PNGStreamingResponse)
def stream_image_no_async_no_annotation():
with read_image() as image_file:
for chunk in image_file:
yield chunk