python - 带有 aiocache 和 Redis 的 FastAPI 无法设置 databases.backends.postgres.Record 对象

Question

我正在尝试使用 aiocache 库在我的端点上实现 Redis。我对 aiocache 进行的第一次测试我使用了@cache，没有指明任何其他服务并且一切正常。但是当我尝试使用 Redis 时，我看到了这个错误（端点仍然返回请求）

ERROR:    Couldn't set [<databases.backends.postgres.Record object at 0x7fb9f01d86a0>, <databases.backends.postgres.Record object at 0x7fb9f01d88b0>, <databases.backends.postgres.Record object at 0x7fb9f01d8a60>] in key app.api.authorget_authors()[], unexpected error
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/aiocache/decorators.py", line 144, in set_in_cache
    await self.cache.set(key, value, ttl=self.ttl)
  File "/usr/local/lib/python3.8/site-packages/aiocache/base.py", line 61, in _enabled
    return await func(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/aiocache/base.py", line 45, in _timeout
    return await asyncio.wait_for(func(self, *args, **kwargs), timeout)
  File "/usr/local/lib/python3.8/asyncio/tasks.py", line 483, in wait_for
    return fut.result()
  File "/usr/local/lib/python3.8/site-packages/aiocache/base.py", line 75, in _plugins
    ret = await func(self, *args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/aiocache/base.py", line 265, in set
    ns_key, dumps(value), ttl=self._get_ttl(ttl), _cas_token=_cas_token, _conn=_conn
  File "/usr/local/lib/python3.8/site-packages/aiocache/serializers/serializers.py", line 140, in dumps
    return json.dumps(value)
TypeError: <databases.backends.postgres.Record object at 0x7fb9f01d8a60> is not JSON serializable

方法是：

@authors.get("/", response_model=List[AuthorOut])                                                                                                                                                                                        
@cached(                                                                                                
     ttl=100,                                                                                            
     cache=Cache.REDIS,
     endpoint="X.X.X.X", #my local ip
     serializer=JsonSerializer(),
     port=6379,
     namespace="main",
     #key="key",
 )
async def get_authors():
   return await db_manager.get_all_authors() 

整个环境基于docker，2个容器，1个FastApi，1个PostgreSQL和1个Redis。

看样子很明显是endpoint返回的对象有问题，请问怎么把这么复杂的对象传给redis呢？

按照 aiochace 文档，我尝试了所有存在的序列化程序，但没有成功。

我的码头工人撰写

version: '3.7'

services:
  book_service:
    build: ./book-service
    command: uvicorn app.main:app --reload --host 0.0.0.0 --port 8000
    volumes:
      - ./book-service/:/app/
    ports:
      - 8001:8000
    environment:
      - DATABASE_URI=postgresql://book_db_username:book_db_password@book_db/book_db_dev
      - AUTHOR_SERVICE_HOST_URL=http://author_service:8000/api/v1/authors/
    depends_on:
      - book_db

  book_db:
    image: postgres:12.1-alpine
    volumes:
      - postgres_data_book:/var/lib/postgresql/data/
    environment:
      - POSTGRES_USER=book_db_username
      - POSTGRES_PASSWORD=book_db_password
      - POSTGRES_DB=book_db_dev
  
  author_service:
    build: ./author-service
    command: uvicorn app.main:app --reload --host 0.0.0.0 --port 8000
    volumes:
      - ./author-service/:/app/
    ports:
      - 8002:8000
    environment:
      - DATABASE_URI=postgresql://author_db_username:author_db_password@author_db/author_db_dev
    depends_on:
      - author_db

  author_db:
    image: postgres:12.1-alpine
    volumes:
      - postgres_data_author:/var/lib/postgres/data
    environment:
      - POSTGRES_USER=author_db_username
      - POSTGRES_PASSWORD=author_db_password
      - POSTGRES_DB=author_db_dev

  nginx:
    image: nginx:latest
    ports:
      - "8080:8080"
    volumes:
      - ./nginx_config.conf:/etc/nginx/conf.d/default.conf
    depends_on:
      - author_service
      - book_service

  redis:
    image: redis:3.2-alpine
    volumes:
      #      - redis_data:/data
      - ./redis.conf:/usr/local/etc/redis/redis.conf
    command: redis-server /usr/local/etc/redis/redis.conf
    ports:
      - 6379:6379

    networks:
      node_net:
        ipv4_address: 172.28.1.4

networks:
  node_net:
    ipam:
      driver: default
      config:
        - subnet: 172.28.0.0/16

volumes:
  postgres_data_book:
  postgres_data_author:
  redis_data:

标签： pythondockerdocker-composeredisfastapi

Answer 1

错误说明了一切

TypeError: <databases.backends.postgres.Record object at 0x7fb9f01d8a60> is not JSON serializable

错误在于您在 JSON 中序列化对象以缓存在 JSON 中不可序列化的对象。

我曾经遇到过类似的问题，但发现 fastAPI 的编码器支持该Record对象，而其他的不支持。您可以返回通过此类编码器序列化的对象，也可以在 redis 缓存参数中将其设置为编码器。请参阅https://fastapi.tiangolo.com/tutorial/encoder/#using-the-jsonable_encoder。

我没有测试以下代码，但应该足以说明我的意思。

from fastapi.encoders import jsonable_encoder

@authors.get("/", response_model=List[AuthorOut])                                                                                                                                                                                        
@cached(                                                                                                
     ttl=100,                                                                                            
     cache=Cache.REDIS,
     endpoint="X.X.X.X", #my local ip
     serializer=JsonSerializer(),
     port=6379,
     namespace="main",
     #key="key",
 )
async def get_authors():
   return jsonable_encoder(await db_manager.get_all_authors())