write a python picture gallery fastapi

在Python中创建一个快速API图片画廊，我们可以使用FastAPI作为Web框架，Uvicorn作为服务器，以及像`Pillow`库处理图像，`pathlib`管理文件路径，`sqlite3`存储图片信息。以下是一个简单的示例：

首先安装所需的库：

pip install fastapi uvicorn pillow sqlalchemy

然后创建一个`main.py`文件，包含以下几个部分：

from fastapi import FastAPI, File, UploadFile
import os
from PIL import Image
from io import BytesIO
from starlette.responses import StreamingResponse
from sqlalchemy import create_engine, Column, Integer, String, Text
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

# 初始化数据库
Base = declarative_base()
engine = create_engine('sqlite:///images_gallery.db')
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

# 数据模型
class ImageGallery(Base):
    __tablename__ = "image_gallery"
    id = Column(Integer, primary_key=True)
    filename = Column(String, unique=True)
    description = Column(Text)

# API配置
app = FastAPI()

@app.on_event("startup")
async def startup():
    Base.metadata.create_all(bind=engine)

@app.post("/upload-image/")
async def upload_image(file: UploadFile = File(...)):
    # 检查文件类型和大小
    if file.content_type not in ["image/jpeg", "image/png"]:
        return {"error": "Invalid image format"}

    if file.size > 4 * 1024 * 1024:  # 限制最大4MB
        return {"error": "Image size exceeds limit"}

    try:
        # 保存图片到临时目录，并获取描述信息
        temp_path = await save_temp_image(file.file)
        description = await get_description_from_user(temp_path)  # 这里假设有一个函数从用户输入获取描述

        # 添加到数据库
        with SessionLocal() as session:
            new_image = ImageGallery(filename=file.filename, description=description)
            session.add(new_image)
            session.commit()

        return {"message": f"Image '{file.filename}' uploaded successfully."}

    except Exception as e:
        return {"error": str(e)}

async def save_temp_image(image_bytes):
    temp_file = BytesIO()
    temp_file.write(image_bytes)
    temp_file.seek(0)
    img = Image.open(temp_file)
    temp_path = "temp/" + file.filename
    img.save(temp_path)
    return temp_path

def get_description_from_user(path):  # 这里需要实现一个实际的交互或API请求获取用户描述
    # 示例：return input("Please describe the image: ")
    pass

@app.get("/{filename}")
async def serve_image(filename: str):
    try:
        with open(os.path.join("temp", filename), 'rb') as image_file:
            response = StreamingResponse(image_file, media_type="image/jpeg")
            response.headers["Content-Disposition"] = f"attachment; filename={filename}"
            return response
    except FileNotFoundError:
        return {"error": "Image not found"}

if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", port=8000)

这个例子展示了基本的图片上传、存储（暂存于本地），以及根据ID返回图片的功能。注意这只是一个基础模板，实际应用可能需要更完善的错误处理和前端界面。