“更新”没有重载与提供的参数匹配

Question

我目前正在阅读 FastAPI 的教程用户指南，pylance 抛出以下警告：

“更新”没有重载与提供的参数匹配PylancereportCallIssue
Typing.pyi(690, 9)：重载 2 是最接近的匹配

这里是抛出警告的代码：

from fastapi import FastAPI

app = FastAPI()

@app.get("/items/")
async def read_items(q: str | None = None):
    results = {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}
    if q:
        results.update({"q": q}) # warning here
    return results

我尝试将

Python › Analysis: Type Checking Mode

更改为

basic

并使用 Pylance 的预发布版本，但警告仍然存在。

Answer 1

q

的类型不明确。

    # At this point, mypy knows that q is either `None`, or _any_ `str`
    if q:  # This fails to disambiguate the situation -- could be "" or None
        assert len(q) > 0
        # Mypy _knows_ for sure that if there was no stack trace
        # and we made it here, then we definitely have a `str`
        results.update({"q": q}) # warning here

最好的方法是

if q is not None: