python type_error ai_generated true

TypeError: 类型 'User' 的对象不是 JSON 可序列化的

TypeError: Object of type 'User' is not JSON serializable

ID: python/fastapi-typeerror-object-of-type-type-is-not-json-serializable

其他格式: JSON · Markdown 中文 · English
80%修复率
87%置信度
0证据数
2024-03-30首次发现

版本兼容性

版本状态引入弃用备注
3.x active — — —

根因分析

直接从端点返回自定义 Python 对象，而未转换为 JSON 可序列化格式。

English

Returning a custom Python object directly from an endpoint without converting to a JSON-serializable format.

generic

解决方案

  1. 95% 成功率 Use a Pydantic model for the response. 
    from pydantic import BaseModel
class UserOut(BaseModel):
    id: int
    name: str

@app.get('/users/{user_id}', response_model=UserOut)
async def get_user(user_id: int):
    user = get_user_from_db(user_id)
    return UserOut(id=user.id, name=user.name)
  2. 90% 成功率 Convert the object to a dictionary manually. 
    @app.get('/users/{user_id}')
async def get_user(user_id: int):
    user = get_user_from_db(user_id)
    return {'id': user.id, 'name': user.name}

无效尝试

常见但无效的做法:

  1. Using json.dumps() on the object directly. 70% 失败

    json.dumps() also requires a serializable object; custom objects need a custom encoder.

  2. Returning the object without a response model. 80% 失败

    FastAPI tries to serialize the object automatically but fails if it's not a dict or Pydantic model.